Summary
Urea and N-alkylureas are N′-alkylated in low yields using aprotic dipolar solvents, like dimethylsulfoxide, solid potassium hydroxide, and alkyl halides. Phase transfer catalysis with tetrabutylammonium chloride in refluxing toluene results in high yield regioselective N′-alkylation of N-alkylureas by means of alkyl halides, tosylates, mesylates, and sulfates as alkylating agents and alkali hydroxide as the base — however, N-arylureas are not alkylated under these conditions. Kinetic studies point to a SN2 type reaction which obeys the Kornblum rule.
Zusammenfassung
Harnstoffe und N-alkylierte Harnstoffe werden in aprotisch dipolaren Lösungsmitteln, wie Dimethylsulfoxid, durch Alkylhalogenide in Gegenwart von Kaliumhydroxid in geringen Ausbeuten N′-alkyliert. Phasentransferkatalyse mit Tetrabutylammoniumchlorid in kochendem Toluol ergibt aus N-Alkylharnstoffen bei Verwendung von Alkyl-Halogeniden, Tosylaten, Mesylaten und Sulfaten als Alkylierungsmittel und Alkalihydroxid als Base hohe Ausbeuten der regioselektiv N′-alkylierten Derivate — allerdings werden N-Arylharnstoffe unter diesen Bedingungen nicht umgesetzt. Untersuchung der Kinetik ergab Hinweise auf eine SN2-Typ Reaktion, die der Regel von Kornblum gehorcht.
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References
E.g.: Vollhardt K. P. C. (1987) Organic Chemistry. Freeman, New York: it should be noted however, that the very ancestor of synthetic organic chemistry is oxalic acid which was prepared by Wöhler from inorganic dicyan three years before his urea synthesis: Wöhler F. (1925) Ann. Phys.3: 177; Wöhler F. (1928) Ann. Phys.12: 253
Houben-Weyl (1952) Methoden der Organischen Chemie8: 149; (1983)E4: 335;E5: 998. Thieme, Stuttgart; Korte F. (ed.) (1974) Methodicum Chimicum6: 716, 732
Szmant H. H. (1989) Organic Building Blocks of Chemical Industry. Wiley, New York
Smith L. I., Emerson O. H. (1949) Org. Synth.29: 18; Tyshchuk G. K., Tsukernavik I. P. (1968) Tr. Tashkent. Politekh. Inst.1968: 17;73: 109456 m
Kornblum N., Coffey G. P. (1966) J. Org. Chem.31: 3447
Gompper R., Wagner H. (1976) Angew. Chem.88: 389
Bristol J. A., Gold E. H., Lovey R. G. (1981) J. Med. Chem.24: 927; Bernardi L., Coda S., Nicoletta V., Vicario G. P., Gioia B., Minghetti A., Vigevanu A., Arcamone F. (1979) Drug Res.29 (II): 1412
Jacobson R. A. (1936) J. Am. Chem. Soc.58: 1984
Krüger H. R., Krähmer H., Rusch R., Sjut V. (1984) Dos 3319008;102: 78895 g
Johnstone R. A. W., Rose M. E. (1979) Tetrahedron35: 2169
Keller W. E., Liotta C. (1986, 1987) Phase Transfer Reactions, Vols 1, 2, Thieme, Stuttgart
Koziara A., Zawadzki S., Zwierzak A. (1979) Synthesis1979: 527; Gajda T., Koziara A., Zawadzki S., Zwierzak A. (1979) Synthesis1979: 549; Gajda T., Zwierzak A. (1981) Synthesis1981: 1005
Reppe W. (1955) Ann. Chem.596: 150
Weisel C. A., Mosher H. S., Whitmore F. C. (1945) J. Am. Chem. Soc.65: 1055
Davis T. L., Blanchard K. C. (1923) J. Am. Chem. Soc.45: 1818
Monsanto Chem. Co. (1956) USP 2,857,430;53: 52016 h
Garbrecht W. L., Herbst R. M. (1953) J. Org. Chem.18: 1014
Buck J. S. R., Baltzly R., Ardis A. E. (1938) J. Am. Chem. Soc.60: 462
Schulz E. M. (1947) J. Am. Chem. Soc.69: 1056
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Hackl, K.A., Falk, H. The synthesis of N-substituted ureas I: The N-alkylation of ureas. Monatsh Chem 123, 599–606 (1992). https://doi.org/10.1007/BF00816855
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DOI: https://doi.org/10.1007/BF00816855