A flexible and modular stereoselective synthesis of (9R,10S)-dihydrosterculic acid

(9R,10S)-Dihydrosterculic acid has been prepared from (SS,SS)-1,1-bis(p-tolylsulfinyl)methane in a sequence involving an asymmetric Corey–Chaykovsky cyclopropanation and two sulfoxide/lithium exchange reactions. In most steps, the reaction conditions had to be optimized for the unbranched alkyl substituents, which were prone to Evans–Mislow rearrangements and subsequent degradation.

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(1R,2S)-0031-(Non-8-enyl)-2-n-octylcyclopropaneC20H38[α]D22=+2.5 (c 0.393, CHCl3)Source of chirality: (1R,2S,5R)-(−)-mentholAbsolute configuration: (1R,2S)

1,1-Bis[(SS)-p-toluenesulfinyl]-2-(non-8-enyl)cyclopropaneC26H34O2S2[α]D22=-113.3 (c 0.233, CHCl3)Source of chirality: (1R,2S,5R)-(−)-mentholAbsolute configuration: (SS,SS,2R)

1-n-Octyl-1-[(SS)-p-toluenesulfinyl]-2-(non-8-enyl)cyclopropaneC27H44OS[α]D22=+54.2 (c 0.273, CHCl3)Source of chirality: (1R,2S,5R)-(−)-mentholAbsolute configuration: (SS,1R,2R)

Methyl (9R,10S)-dihydrosterculate/methyl 8-((1R,2S)-2-octylcyclopropyl)octanoateC20H38O2[α]D22=+1.7 (c 0.573, CHCl3)Source of chirality: (1R,2S,5R)-(−)-mentholAbsolute configuration: (9R,10S)