Delesserine (2226) is a secondary metabolite isolated from the alga Delesseria sanguinea (Lamouroux). Its relative configuration has been determined by X-ray crystal structure analysis . Although aqueous extracts of D. sanguinea collected on the European Atlantic coast are powerful anticoagulants for human blood , delesserine does not exhibit this property. The first synthesis of 2226, by Seebach , is shown in Scheme 395. Condensation of ester 2222 with aldehyde 2223 (available in four steps from diethyl tartrate) gives a mixture of four diastereomers 2224. Oxidation of 2224 and treatment with TsOH in methanol provides lactone 2225 in 32% yield along with 59% of its diastereomer. Removal of the benzyl protecting groups affords (+)-delesserine in four steps (eight steps from diethyl tartrate) and 18% overall yield.
KeywordsAldehyde Diol Enolate Ephedrine Aldol
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