Abstract
Development of a unified total synthesis of madangamine alkaloids is described. The synthesis consists of three parts: (1) construction of the central ABC-ring, (2) installation of the skipped diene bearing a trisubstituted olefin, and (3) the synthesis of various D-rings from a tetracyclic ABCE-common intermediate. The ABC-tricyclic framework is successfully assembled by intramolecular allenylation. The most significant issue in this synthesis is the stereoselective installation of the skipped diene. This challenge is ultimately overcome by development of a stereodivergent approach using hydroboration of allenes and Migita-Kosugi-Stille coupling. The hydroboration is especially useful because the reaction of 1,1-disubstituted allenes with either 9-BBN or (Sia)2BH gives (E)- or (Z)-allylic alcohols, respectively. The key to the success of our unified total synthesis is macrocyclic alkylation to form a wide variety of D-rings from the tetracyclic ABCE-common intermediate. Our collective synthesis of madangamine alkaloids revealed structure–activity relationship of D-rings in their cytotoxicity against human cancer cell lines.
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12.1 Madangamine Alkaloids
In 1994, Andersen isolated madangamine A (1) from the marine sponge Xestospongia ingens in Papua New Guinea (Fig. 12.1) [1,2,3]. Although madangamine A (1) appears to be a macrocyclic diamine alkaloid biogenetically synthesized from bis-3-alkylpyridine found in the manzamine alkaloids [4], it possesses a unique tricyclic ABC-core structure. Andersen et al. [5] also isolated madangamines B-E (2–5) from the same sponge. These alkaloids share an ABCE-common tetracyclic core with various types of D-rings. The Berlinck group documented the isolation of madangamine F (6), which has highly oxidized forms of the C- and E-rings, from a sponge Pachychalina alcaloidifera [6]. While madangamines A (1) and F (6) were found to show antiproliferative effects against human cancer cell lines [3, 6], the biological activities of other madangamines were not elucidated due to the limited availability of the natural samples. In 2014, the Amat group opened up a new stage by the first total synthesis of madangamine D (4) [7]. They revealed that madangamine D (4) exhibited a different antitumor cytotoxic spectrum from madangamine A (1), indicating that variable D-rings might be crucial in their cytotoxicity. After Amat’s report, our group documented the synthesis of madangamines A-E (1–5) in 2017 and 2019 [8, 9]. Recently, the Dixon group reported an elegant synthesis of madangamine E (5) based on the organocatalytic desymmetrization in 2022 [10].
Structures of madangamine alkaloids
In this chapter, we report our synthetic journey to the unified total synthesis of madangamine alkaloids. Structurally, these alkaloids presented synthetic challenges including: (1) construction of the diazatricyclic ABC-ring, (2) stereoselective synthesis of the skipped diene, and (3) construction of the various D-rings at the late stage (Fig. 12.1). At the beginning of our 7-year study, we expected that the highlight of this total synthesis would be the first challenge, i.e., construction of the unprecedented ABC-tricyclic ring. In fact, most synthetic reports from other groups focused on the development of a method to assemble the tricyclic skeleton [1, 2]. However, through this synthetic project, we found that the most daunting challenge was the stereoselective construction of the skipped diene. We ultimately developed a stereodivergent approach that gave all four possible stereoisomers of the skipped dienes from a 1,1-disubstituted allene. Another significant challenge proved to be the installation of the variable D-rings to a common tetracyclic intermediate. Finally, we found that macrocyclic alkylation through the SN2 process was highly general for the unified synthesis of these D-rings.
12.2 Synthetic Plan
To elucidate the structure–activity relationship involving variable D-rings, a supply of pure madangamine alkaloids by a unified total synthesis is essential. Therefore, our synthetic plan centered on construction of the D-rings from the ABCE-tetracyclic common intermediate 13 at the late stage. The distinctive diazatricyclic ABC-ring (Z,Z)-12 would be synthesized from enyne unit 7. Transition metal-catalyzed cycloisomerization of 7 would promote construction of the B-ring, associated with the formation of the exo-olefin. Hydroboration of the resulting bicyclic AB-ring 8 could generate B-alkyl borane 9, which could undergo Suzuki–Miyaura coupling with 10 to provide ene carbamate 11. Addition of an acid to 11 would promote formation of the N-acyliminium ion and subsequent cyclization of the vinyl silane to give tricyclic ABC-ring (Z,Z)-12. The common intermediate 13 would be obtained from 12 by macrolactamization. The collective total synthesis of the madangamine alkaloids could be completed by installation of a variety of D-rings (Scheme 12.1).
Synthetic plan toward unified total synthesis of madangamine alkaloids
12.3 Construction of Diazatricyclic ABC-Framework
12.3.1 Enantioselective Synthesis of A-Ring
Our synthetic program began with the synthesis of A-ring moiety 24 (Scheme 12.2). N-Boc-glycine 14 was transformed to vinyl tosylate 15, which underwent Suzuki–Miyaura coupling, providing trisubstituted enoate 16 in 83% yield [11]. Addition of DIBAL-H and BF3·Et2O [12] to 16 promoted regioselective 1,2-reduction to give the primary alcohol, which was converted to acetate 17. After installation of the allyl group to Boc-carbamate 17, methanolysis in a one-pot process gave allylic alcohol 18, which was converted to chiral secondary alcohol 20 by IBX oxidation and catalytic enantioselective alkylation in 97% ee [13]. Subsequent Johnson-Claisen rearrangement of 20 created the quaternary carbon center through chirality transfer of the secondary alcohol. Carbamate 23 was synthesized from 21 by three-step procedure including hydrolysis, amidation, and the Hofmann rearrangement with PhI(OAc)2. The ring-closing metathesis of 23 with 5 mol% of Grubbs second catalyst afforded A-ring moiety 24. The enantiomeric excess of 24 was 92% ee, indicating that the Claisen rearrangement did not proceed with complete chirality transfer.
Enantioselective synthesis of A-ring through Johnson-Claisen rearrangement
Although the developed route gave the A-ring moiety 24 in 13 steps from a commercially available compound, we pursued a more concise and robust route toward the unified total synthesis (Scheme 12.3). The new approach was based on the quick formation of the tetrahydropiperidine ring by Ni-catalyzed [4 + 2] cycloaddition [14] and chirality transfer through the SN2′ reaction. The second-generation route to the A-ring moiety 24 began with synthesis of protected propargylic amine 28 in three steps including protection of benzyl amine with TMS-ethanol 25, N-propargylation, and protection of the terminal alkyne. Louie reported Ni-catalyzed [4 + 2] cycloaddition between a 3-azetidinone and an alkyne [14]. This method was applicable to our case, providing 3-dihydropyridones 30 and 31 as an inseparable mixture. The resulting ketones underwent the CBS reduction [15] to provide a separable mixture of secondary alcohols 32 and 33 in 78 and 7.2% yields, respectively (95% ee for both diastereomers). It is noteworthy that the TMS group of the terminal alkyne played a number of crucial roles in this synthesis. For instance, the [4 + 2] cycloaddition did not proceed without the TMS group. Louie reported that the TMS group preferred to be on the α-position in the [4 + 2] cycloaddition (32:33 = 10.8:1), as well as the high enantioselectivity in the following reduction. Treatment of 33 with t-BuOK cleaved the TMS group by the Brook rearrangement. The resulting allylic alcohol was transformed to picolinate 34. The quaternary stereocenter of the A-ring was established by Kobayashi’s anti-SN2′ reaction in 97% yield [16] without loss of the enantiomeric excess. The N-benzyl group was removed by Birch reduction. Thus, the improved route afforded A-ring moiety 24 in nine steps from commercially available TMS-ethanol 25.
Enantioselective synthesis of A-ring through SN2′ reaction
12.3.2 Synthesis of AB-Ring by Pd-Catalyzed Cycloisomerization
With A-ring 24 in hand, the next challenge was the cycloisomerization to construct the B-ring (Scheme 12.4). After N-propargylation of 24, palladium-catalyzed cycloisomerization of enyne 7 [17, 18] provided bicyclic compound 8 in 45% yield. We expected that subsequent hydroboration of olefin 8 could establish the third stereocenter of the B-ring. Unfortunately, no desired product 9 was obtained.
Synthesis of AB-ring by Pd-catalyzed cycloisomerization
To increase the reactivity of the exo-olefin after the cycloisomerization, we installed an electron-withdrawing group onto the terminal alkyne of 7 (Scheme 12.4b). Treatment of the lithium acetylide derived from alkyne 7 with methyl chloroformate led to the formation of methyl alkynoate 35. Gratifyingly, the additional methyl ester in 35 improved the cycloisomerization [17, 18] to provide bicyclic compound 36 in 87% yield. Furthermore, the methyl ester enhanced the electrophilicity of the olefin, which enabled stereoselective 1,4-addition under Narisada’s conditions (NaBH4, CuCl) [19], giving bicyclic AB-ring 37 in 94% yield with 10.8:1 diastereoselectivity.
12.3.3 Construction of Tricyclic ABC-Ring by N-Acyliminium Cyclization
The next stage was the construction of the C-ring by N-acyliminium cyclization [20]. Originally, we planned to use the N-acyliminium cyclization of the vinyl silane after the Suzuki–Miyaura coupling as shown in Scheme 12.1. However, installation of the methyl ester for the successful cycloisomerization required the allyl silane instead of the vinyl silane as a nucleophile (Scheme 12.5). Reduction of methyl ester 37 via the Weinreb amide provided aldehyde 38. The Wittig reaction of 38, followed by a cross metathesis reaction formed allyl silane 39 (E/Z = 4:1). Treatment of a solution of 39 in CH2Cl2 with BF3·Et2O in the presence of EtOH initiated the generation of the N-acyliminium ion, and subsequent intramolecular cyclization, affording 40 in 66% yield. Although tricyclic intermediate 40 was obtained, the terminal olefin could not be converted to the trisubstituted olefin embedded in common intermediate (Z,Z)-12.
Synthesis of ABC-ring by intramolecular allylation via N-acyliminium ion
12.4 Stereoselective Synthesis of Skipped Diene
12.4.1 Precedents for Synthesis of Z-Trisubstituted Olefin in Skipped Diene of Madangamine Alkaloids
Before we tackled this issue, some synthetic studies to construct the trisubstituted olefin had already been documented (Scheme 12.6) [21]. Yamazaki and Kibayashi reported a model study using bicyclic ketone 41. The Still-Gennari conditions enabled the Z-selective synthesis of trisubstituted olefin 42. The Amat group showed that Wittig coupling of bicyclic ketone 43 with the unstable ylide derived from 44 stereoselectively constructed the (Z,Z)-skipped diene [22]. However, the high (Z)-selectivity was not achieved from 46 in the total synthesis of madangamine D (4) [7]. After our reports, the Dixon group also discovered a successful method to give access to the (Z)-trisubstituted olefin by elimination of tertiary alcohol 48 with SOCl2 and DTBMP [10].
Precedents for synthesis of Z-trisubstituted olefin in skipped diene of madangamine alkaloids
At this stage, we realized that (Z)-selective synthesis of the trisubstituted olefin in the skipped diene was highly challenging, and searched the literature for natural products including skipped dienes (Fig. 12.2) [23, 24]. This structural motif is widely distributed in polyunsaturated fatty acids, polyketides, and alkaloids. One of the structural features is the diversity of stereochemistries involving the two olefins including trisubstituted olefins. Ideally, the method should give all four possible stereoisomers from the same intermediate. In addition, considering the high complexity of these natural products, the method should be convergent though fragment coupling under mild reaction conditions so as not to induce isomerization to the more stable 1,3-dienes.
Representative natural products containing skipped dienes
To develop practical methods applicable to the synthesis of a variety of skipped diene natural products, we envisioned a stereodivergent approach consisting of hydroboration of 1,1-disubstituted allenes [25,26,27,28] and Migita–Kosugi–Stille coupling [29] (Scheme 12.7). Allenes have been utilized as attractive intermediates in the total synthesis of natural products [30]. However, control of the various selectivities involving the two orthogonal π-bonds is essential. Indeed, three selectivities must be solved in the hydroboration/oxidation of 1,1-disubstituted allenes. The first is the regioselectivity of the two double bonds. The second is the facial selectivity from either path A or path B, which could be controlled by differentiating the steric hindrance with RL or RS in allene 54. In general, hydroboration of allene 54 proceeds from the less hindered side opposite to RL (path B) to give allylic borane (Z)-55. Third, the most challenging selectivity involves the [1,3]-allylic rearrangement of 55 [25,26,27,28]. Kinetically favored (Z)-55 is often transformed to thermodynamically favored (E)-55 through two reversible [1,3]-allylic rearrangements. If these three selectivities are precisely controlled, both trisubstituted allylic alcohols (E)-57 and (Z)-57 would be obtained through the hydroboration of allene 54 after oxidative quench. Associated with palladium-catalyzed coupling with vinyl stannanes (E)-58 and (Z)-58 [29], the method would become stereodivergent to provide all four possible stereoisomers 59 from the same 1,1-disubstituted allene 54.
Plan for stereodivergent synthesis of skipped dienes by hydroboration of allenes and Migita–Kosugi–Stille coupling
Our stereodivergent hydroboration of 1,1-disubstituted allene 60 was realized by simply changing the steric hindrance of the organoborane reagents (Scheme 12.8). While the hydroboration with 9-BBN at room temperature provided allylic alcohol (E)-61 through 1,3-allylic rearrangements, the reaction with (Sia)2B at 0 °C gave allylic alcohol (Z)-61 without causing 1,3-allylic rearrangements due to the larger siamyl group. Allylic alcohols (E)-61 and (Z)-61 were converted to carbamates (E)-62 and (Z)-62, respectively. The Migita-Kosugi-Stille coupling of both carbamates 62 with vinyl stannanes (E)-63 and (Z)-63 provided four stereoisomers of skipped dienes 64. As shown in Fig. 12.2, the stereocontrol of trisubstituted olefins seen in these natural products is still challenging in modern organic synthesis compared with that of disubstituted olefins. However, our method stereoselectively provided all four possible stereoisomers including the trisubstituted olefin.
Stereodivergent synthesis of the skipped dienes
12.4.2 Synthesis of the Tetracyclic ABCE-Common Intermediate Including the Skipped Diene
Having a practical method to gain access to skipped dienes from 1,1-disubstituted allenes, the stage was set for the synthesis of the skipped diene embedded in madangamine alkaloids (Scheme 12.9). As shown in Scheme 12.5, we achieved construction of the C-ring by intramolecular allylation via the N-acyliminium ion. This success encouraged us to employ propargyl silane 65 because it gives ABC-tricyclic framework 66, accompanied by formation of the 1,1-disubstituted allene. The resulting allene 66 would be converted to skipped diene (Z,Z)-12 by Z-selective hydroboration and palladium-catalyzed coupling.
Plan for synthesis of the ABC-ring including the skipped diene
The synthesis of propargyl silane 65 commenced with the Ohira-Bestmann reaction of aldehyde 38 [31, 32] and alkylation with ICH2TMS (Scheme 12.10). Addition of CF3CO2H to propargyl silane 65 resulted in the formation of N-acyliminium ion 68. For successful cyclization, a conformational change from the most stable conformer 68a was essential to place the equatorial propargyl silane in the axial position as shown in 68b. Regardless, the cyclization proceeded smoothly to give ABC-ring 66 in 85% yield. Use of ethanol as a co-solvent to form transient N,O-acetal 69 was important probably because it tentatively protects the unstable N-acyliminium ion and increases chances for the requisite conformational flip without decomposition. In addition, ethanol lowered the acidity of CF3CO2H. In a control experiment without ethanol, the cyclization was observed even at room temperature, but the TIPS group was significantly cleaved (66: 52%; 70: 32%). Thus, we achieved intramolecular allenylation to construct the ABC-ring with the 1,1-disubstituted allene.
Synthesis of the ABC-ring by intramolecular allenylation via N-acyliminium ion
The stage was set for the construction of the crucial skipped diene (Scheme 12.11). Hydroboration of allene 66 with sterically small 9-BBN, followed by oxidative workup, provided (E)-71 in 83% yield (E:Z = 6.1:1). In contrast, desired trisubstituted allylic alcohol (Z)-71 was produced in 93% yield (E:Z = 1:20) when using sterically large (Sia)2BH. Conversion of allylic alcohol (Z)-71 to carbonate 72, followed by the coupling reaction with vinyl stannane (Z)-73, afforded skipped diene (Z,Z)-12 in high yield.
Synthesis of the tetracyclic ABCE-common intermediate of madangamine alkaloids through stereoselective construction of the skipped diene
With skipped diene (Z,Z)-12 in hand, the next challenge was the macrolactamization to form the eleven-membered E-ring (Scheme 12.11). Hydrolysis of the methyl ester in (Z,Z)-12 and removal of the Boc group in 74 delivered the amino acid. The Mukaiyama reagent (CMPI: 2-chloro-1-methylpyridinium iodide) [33] proved to be the best reagent for this macrolactamization to provide 75 (75%, 2 steps). Cleavage of the TIPS group in 75 was realized with CSA in methanol at 40 °C. Thus, ABCE-tetracyclic framework 13 was obtained as a common intermediate toward the unified total synthesis of madangamine alkaloids.
12.5 Unified Total Synthesis of Madangamines A-E
Macrocyclic diamine structures are widely observed in manzamine alkaloids. However, development of general methods to synthesize this structural motif remains a formidable issue. The construction of the D-rings in the madangamine alkaloids was highly challenging because they possess various ring sizes and degrees of unsaturation (Fig. 12.1). Ring closing metathesis (RCM) has been recognized as one of the most promising reactions to form macrocycles. In fact, both the Amat and Dixon groups independently employed the olefin metathesis to construct the D-ring in their total syntheses (Scheme 12.12, 76 → 77 [7], 79 → 80 [10]). However, synthesis of madangamines D and E (4,5) required hydrogenation to form saturated D-rings after RCM (77 → 78 [7], 80 → 81 [10]). The construction of the E-ring had to be performed after installation of the D-ring due to the presence of the skipped diene. Therefore, our collective synthesis via the tetracyclic common intermediate cannot employ the RCM approach. As another disadvantage to the use of olefin metathesis, the products are often obtained as a mixture of E/Z stereoisomers, which would be problematic in the case of madangamines A, B, and C (1–3) with unsaturated D-rings. Thus, the unified total synthesis required the development of practical methods that did not depend on the ring size and the degree of unsaturation of the D-rings, without affecting the E-ring.
Examples of the synthesis of the macrocyclic D-ring by other groups
Macrolactamization of an amino acid was the first choice to meet the above requirements in the synthesis of madangamine C (3) (Scheme 12.13). AZADO-oxidation [34] of primary alcohol 13 and subsequent Wittig reaction with 83 introduced the unsaturated side chain with complete Z-selectivity, giving 84 in 88% yield. Hydrolysis and removal of the Teoc group gave the amino acid, which underwent the macrolactamization with EDCI and HOBt [7, 22] to give pentacyclic compound 85. Finally, LiAlH4 reduction of the amide group accomplished the total synthesis of madangamine C (3).
Total synthesis of madangamine C
Although madangamine C (3) was obtained, we found that the macrolactamization was not applicable to other members of the madangamines. For example, the macrolactamization for the synthesis of madangamine E (5) was not successful as follows (Scheme 12.14a). Primary alcohol 13 was converted to bromide 86, which underwent Cahiez’s alkylation with Grignard reagent 87 in the presence of the copper catalyst [35]. Cleavage of the TIPS group with CSA in MeOH provided primary alcohol 88, which was subjected to TEMPO-oxidation to provide carboxylic acid 89. After transformation to the amino acid, macrolactamization resulted in low yield, likely because the unfavorable dimer was competitively formed due to the lack of the Z-olefin, which supported macrolactamization by the proximity effect to form madangamine C (3).
Total synthesis of madangamine E
For successful macrocyclization, we believed that reactions at elevated temperature would be essential to adopt the appropriate conformation for cyclization (Scheme 12.14b). Thus, functional groups at both sites should possess the proper reactivity and stability to react at elevated temperature. To meet these requirements, we planned to take advantage of macrocyclic alkylation using the secondary amine and the tosylate through SN2 reaction. First, the primary alcohol of 88 was converted to tosylate 91, which was subjected to BF3·Et2O-mediated cleavage of the Teoc group. As we expected, the macrocyclic alkylation at 80 °C in the presence of K2CO3 took place without detection of the corresponding dimer, affording pentacyclic compound 92 in 61% yield (two steps). Finally, reduction of 92 completed the total synthesis of madangamine E (5).
The macrocyclic alkylation was widely applicable to install various types of D-rings (Scheme 12.15a). Madangamine D (4), which has a fourteen-membered saturated D-ring instead of the thirteen-membered D-ring in madangamine E (5), was successfully synthesized by the same sequence using Grignard reagent 93. Madangamine A (1) was one of the most challenging targets due to the sensitive (Z,Z,Z)-skipped triene (Scheme 12.15b). However, the macrocyclic alkylation approach was effective even for the total synthesis of madangamine A (1). The Wittig coupling of 53 using phosphonium salt 96 and cleavage of the TIPS group provided 97 including the (Z,Z,Z)-skipped triene as a single diastereomer. As an initial experiment, oxidation of the primary alcohol was attempted to give the acid for the macrolactamization. However, significant decomposition was observed probably due to the skipped triene. In contrast, the tosylate was easily prepared from the primary alcohol in 97. After formation of the free amino group, the fifteen-membered D-ring was successfully constructed by macrocyclic alkylation with iPr2NEt in MeCN at 70 °C. Pentacyclic intermediate 98 was produced in 59% yield over two steps. Reduction of 98 resulted in the total synthesis of madangamine A (1).
Total synthesis of madangamines A and D
The structure of madangamine B (2) is similar to that of madangamine A (1) except for the position of one double bond in the fifteen-membered D-ring (Scheme 12.16). However, the location of this double bond rendered the synthesis from the common intermediate more complicated. For example, aldehyde 53 was not a productive intermediate for the direct coupling reaction to install the side chain. In addition, the (E)-stereochemistry of the double bond in madangamine B (2) prevented the use of the reliable (Z)-selective Wittig reaction. The construction of the D-ring started with one-carbon dehomologation. The Ishihara group reported α-oxyacylation of aldehydes via a radical intermediate [36], which was applied to aldehyde 53 to give 99. Reduction of aldehyde 99 and methanolysis formed the diol, which was cleaved with Pb(OAc)4 to give aldehyde 100. Installation of the side chain was achieved with stepwise coupling reactions using the (E)-selective CrCl2-mediated Takai-Uchimoto olefination [37], and the (Z)-selective Wittig reaction using phosphonium salt 103. After preparation of the tosylate and the secondary amine in three steps, macrocyclic alkylation successfully constructed the fifteen-membered D-ring. Finally, LiAlH4 reduction of the remaining lactam carbonyl group accomplished the total synthesis of madangamine B (2). Thus, we achieved the unified total synthesis of madangamines (1–5) from the ABCE-tetracyclic common intermediate.
Total synthesis of madangamine B
12.6 Biological Activities of Madangamines A-E
With pure synthetic samples of madangamine alkaloids A-E (1–5) in hand, their cytotoxicities against thirteen human cancer cell lines were evaluated (Table 12.1) [9]. Their IC50 values revealed that the antiproliferative effects depended on the degree of unsaturation in the D-rings. Thus, madangamines A (1) and B (2) proved to be the most potent alkaloids. In the growth inhibition by madangamine A (1), the levels of autophagy-related proteins (LC3-II and p62) increased, associated with lysosome enlargement and increase in lysosomal pH [38]. These results suggested that madangamine A (1) is a novel lysosome inhibitor and exercised its cytotoxicity by the inhibition of lysosome function.
12.7 Conclusion
In this chapter, we discussed our synthetic journey to the madangamine alkaloids. In the beginning, we focused on the construction of the ABC-tricyclic framework. During the synthetic study, stereoselective installation of the skipped diene proved to be the most challenging. To solve this problem, we developed a stereodivergent method consisting of hydroboration with either 9-BBN or (Sia)2BH to give (E)- or (Z)-stereoisomers, and Migita-Kosugi-Stille coupling. This method delivered all four possible stereoisomers of the skipped dienes from the same allene. The developed method enabled the synthesis of the skipped diene embedded in the madangamine alkaloids after intramolecular allenylation. The collective synthesis of madangamines A-E was achieved via the ABCE-tetracyclic common intermediate. Macrocyclic alkylation proved to be highly effective to install various types of the D-rings. Our synthesis of madangamine alkaloids provided a series of pure samples for evaluating the antiproliferative effects against human cancer cell lines, indicating that a high degree of unsaturation in D-rings was crucial. In addition, madangamine A exhibited its cytotoxicity by the inhibition of lysosome function. We believe that our unified total synthesis of the madangamine alkaloids will contribute to the development of both synthesis and biology involving skipped dienes and macrocyclic diamine natural products.
References
For a review on madangamine alkaloids, see; Amat M, Pérez M, Ballette R, Proto S, Bosch J (2015) The alkaloids of the madangamine group. The Alkaloids 74:159–199. https://doi.org/10.1016/bs.alkal.2014.10.001
Tang Y, Zhu L, Hong R (2022) Madangamine alkaloids: Madness and tranquility. Tetrahedron Chem 3:100025. https://doi.org/10.1016/j.tchem.2022.100025 and references including synthetic studies of madangamine alkaloids therein
For a recent review on manzamine alkaloids, see; Kubota T, Kurimot S, Kobayashi J (2020) The manzamine alkaloids. The Alkaloids 84:1–124. https://doi.org/10.1016/bs.alkal.2020.03.001
Kong F, Andersen RJ, Allen TM (1994) Madangamine A, a novel cytotoxic alkaloid from the marine sponge Xestospongia ingens. J Am Chem Soc 116:6007–6008. https://doi.org/10.1021/ja00092a077
Kong F, Graziani EI, Andersen RJ (1998) Madangamines B-E, pentacyclic alkaloids from the marine sponge Xestospongia ingens J Nat Prod 61:267–271. https://doi.org/10.1021/np970377r
de Oliveira JHHL, Nascimento AM, Kossuga MH, Cavalcanti BC, Pessoa CO, Moraes MO, Macedo ML, Ferreira AG, Hajdu E, Pinheiro US, Berlinck RGS (2007) Cytotoxic alkylpiperidine alkaloids from the Brazilian marine sponge Pachychalina alcaloidifera. J Nat Prod 70:538–543. https://doi.org/10.1021/np060450q
Ballette R, Pérez M, Proto S, Amat M, Bosch J (2014) Total synthesis of (+)-madangamine D. Angew Chem Int Ed 53:6202–6205. https://doi.org/10.1002/anie.201402263
Suto T, Yanagita Y, Nagashima Y, Takikawa S, Kurosu Y, Matsuo N, Sato T, Chida N (2017) Unified total synthesis of madangamines A, C, and E. J Am Chem Soc 139:2952–2955. https://doi.org/10.1021/jacs.7b00807
Suto T, Yanagita Y, Nagashima Y, Takikawa S, Kurosu Y, Matsuo N, Miura K, Simizu S, Sato T, Chida (2019) Unified total synthesis of madangamine akaloids. Bull Chem Soc Jpn 92:545–571. https://doi.org/10.1246/bcsj.20180334
Shiomi S, Shennan BDA, Yamazaki K, Fuentes de Arriba ÁL, Vasu D, Hamlin TA, Dixon DJ (2022) A new organocatalytic desymmetrization reaction enables theenantioselective total synthesis of madangamine E. J Am Chem Soc 144: 1407–1415. https://doi.org/10.1021/jacs.1c12040
Baxter JM, Steinhuebel D, Palucki P, Davies IW (2005) Stereoselective enol tosylation: preparation of trisubstituted α,β-unsaturated esters. Org Lett 7:215–218. https://doi.org/10.1021/ol047854z
Moriwake T, Hamano S, Miki D, Saito S, Torii S (1986) A selective 1,2-reduction of γ-amino-α,β-unsaturated esters by means of BF3·OEt2-DIBAL-H system. Highly versatile chiral building blocks from α-amino acids. Chem Lett 815–818. https://doi.org/10.1246/cl.1986.815
Takahashi H, Kawakita T, Ohno M, Yoshioka M, Kobayashi S (1992) A catalytic enantioselective reaction using a C2-symmetric disulfonamide as a chiral ligand: Alkylation of aldehydes catalyzed by disulfonamide-Ti(O-i-Pr)4-dialkyl zinc system. Tetrahedron 48:5691–5700. https://doi.org/10.1016/0040-4020(92)80020-G
Kumar P, Louie J (2012) A single step approach to piperidines via Ni-catalyzed β-carbon elimination. Org Lett 14:2026–2029. https://doi.org/10.1021/ol300534j
Corey EJ, Bakshi RK, Shibata S (1987) Highly enantioselective borane reduction of ketones catalyzed by chiral oxazaborolidines. Mechanism and synthetic implications. J Am Chem Soc 109:5551–5553. https://doi.org/10.1021/ja00252a056
Kaneko Y, Kiyotsuka Y, Acharya HP, Kobayashi Y (2010) Construction of a quaternary carbon at the carbonylcarbon of the cyclohexane ring. Chem Commun 46:5482–5484. https://doi.org/10.1039/C0CC00653J
Trost BM, Tanoury GJ, Lautens M, Chan C, MacPherson DT (1994) Pd-catalyzed cycloisomerization to 1,2-dialkylidenecycloalkanes. 1. J Am Chem Soc 116:4255–4267. https://doi.org/10.1021/ja00089a015
Trost BM, Ferreira EM, Gutierrez AC (2008) Ruthenium- and palladium-catalyzed enyne cycloisomerizations: differentially stereoselective syntheses of bicyclic structures J Am Chem Soc 130:16176–16177. https://doi.org/10.1021/ja8078835
Narisada M, I. Horibe I, Watanabe F, Takeda K (1989) Selective reduction of aryl halides and α,β-unsaturated esters with sodium borohydride-cuprous chloride in methanol and its application to deuterium labeling. J Org Chem 54:5308–5313. https://doi.org/10.1021/jo00283a025
Yanagita Y, Suto T, Matsuo N, Kurosu Y, Sato T, Chida N (2015) Synthesis of diazatricyclic common structure of madangamine alkaloids. Org Lett 17: 1946–1949. https://doi.org/10.1021/acs.orglett.5b00661
Yoshimura Y, Inoue J, Yamazaki N, Aoyagi S, Kibayashi C. (2006) Synthesis of the 11-membered ring of the marine alkaloids, madangamines. Tetrahedron Lett 47:34893492. https://doi.org/10.1016/j.tetlet.2006.02.160
Proto S, Amat M, Pérez M, Ballette R, Romagnoli F, Manci-nelli A, Bosch J, (2012) Model studies on the synthesis of madangamine alkaloids. Assembly of the macrocyclic rings. Org Lett 14:3916–3919. https://doi.org/10.1021/ol301672y
Petruncio G, Shellnutt Z, Elahi-Mohassel S, Alishetty S, Paige M (2022) Skipped dienes in natural product synthesis. Nat Prod Rep 38:2187–2213. https://doi.org/10.1039/D1NP00012H
Sato T, Suto T, Nagashima Y, Mukai S, Chida N (2021) Total synthesis of skipped diene natural products. Asian J Org Chem 10:2486–2502. https://doi.org/10.1002/ajoc.202100421
Brown HC, Liotta R, Kramer G W (1979) Hydroboration. 51. Hydroboration of representative allenes with 9-borabicyclo[3.3.1]nonane. An exceptional directive effect providing a direct synthesis of B-allyl-9-borabicyclo[3.3.1]nonane derivatives. J Am Chem Soc 101:2966–2970. https://doi.org/10.1021/ja00505a025
Kister J, DeBaillie AC, Lira R, Roush WR (2009) Stereoselective synthesis of γ-substituted (Z)-allylic boranes via kinetically controlled hydroboration of allenes with 10-TMS-9-borabicyclo[3.3.2]decane. J Am Chem Soc 131:14174–14175. https://doi.org/10.1021/ja905494c
Yang L, Lin Z, Huang SH, Hong R (2016) Stereodivergent synthesis of functionalized tetrahydropyrans accelerated by mechanism-based allylboration and bioinspired oxa-Michael cyclization. Angew Chem Int Ed 55:6280–6284. https://doi.org/10.1002/anie.201600558
Nagashima Y, Sasaki K, Suto T, Sato T, Chida N (2018) Stereodivergent hydroboration of Allenes. Chem Asian J 13:1024–1028. https://doi.org/10.1002/asia.201800134
Valle LD, Stille JK, Hegedus LS (1990) Palladium-catalyzed coupling of allylic acetates with aryl- and vinylstannanes. J Org Chem 55:3019–3023. https://doi.org/10.1021/jo00297a014
For a review on allenes in natural product synthesis, see; Yu S, Ma S (2012) Allenes in catalytic asymmetric synthesis and natural products syntheses. Angew Chem Int Ed 51:3074–3112. https://doi.org/10.1002/anie.201101460
Ohira S (1989) Methanolysis of dimethyl (1-diazo-2-oxopropyl) phosphonate: Generation of dimethyl (diazomethyl) phosphonate and reaction with carbonyl compounds. Synth Commun 19:561–564. https://doi.org/10.1080/00397918908050700
Müller S, Liepold B, Roth GJ, Bestmann HJ (1996) An improved one-pot procedure for the synthesis of alkynes from aldehydes. Synlett 521–522. https://doi.org/10.1055/s-1996-5474
Mukaiyama T, Usui M, Saigo K (1976) The facile synthesis of lactones. Chem Lett 49–50. https://doi.org/10.1246/cl.1976.49
Shibuya M, Tomizawa M, Suzuki I, Iwabuchi Y (2006) 2-Azaadamantane N-oxyl (AZADO) and 1-Me-AZADO: Highly efficient organocatalysts for oxidation of alcohols. J Am Chem Soc 128:8412–8413. https://doi.org/10.1021/ja0620336
Cahiez G, Chaboche C, Jézéquel M (2000) Cu-catalyzed alkylation of Grignard reagents: A new efficient procedure. Tetrahedron 56:2733–2737. https://doi.org/10.1016/S0040-4020(00)00128-9
Uyanik M, Suzuki D, Yasui T, Ishihara K (2011) In situ generated (hypo)iodite catalysts for the direct α-oxyacylation of carbonyl compounds with carboxylic acids. Angew Chem Int Ed 50:5331–5334. https://doi.org/10.1002/anie.201101522
Okazoe T, Takai K, Utimoto K (1987) (E)-Selective olefination of aldehydes by means of gem-dichromium reagents derived by reduction of gem-diiodoalkanes with chromium(II) chloride. J Am Chem Soc 109:951–953. https://doi.org/10.1021/ja00237a081
Miura K, Kawano S, Suto T, Sato T, Chida N, Simizu S (2021) Identification of madangamine A as a novel lysosomotropic agent to inhibit autophagy. Bioorg Med Chem 34:116041. https://doi.org/10.1016/j.bmc.2021.116041
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Sato, T. (2024). Unified Total Synthesis of Madangamine Alkaloids. In: Nakada, M., Tanino, K., Nagasawa, K., Yokoshima, S. (eds) Modern Natural Product Synthesis. Springer, Singapore. https://doi.org/10.1007/978-981-97-1619-7_12
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