Stereoselective synthesis of alcohols, XXXI: Stereoselective CC bond formation using chiral Z ‐pentenylboronates

Using 1,2‐dicyclohexyl‐1,2‐ethanediol as chiral auxiliary, the enatiomerically pure Z ‐pentenylboronate 9c was obtained. Its addition to benzaldehyde proceeded with complete transfer of chirality to give the syn ‐ E ‐homoallyl alcohol 11 . The ability of the reagent 9c to create new stereocenters under reagent control of diastereoselectivity was tested in its addition to the chiral aldehydes 15 and 24 . This resulted in a short and stereospecific synthesis of invictolide ( 18 ), as well as of a C‐9/C‐15‐partial structure 25 of erythronolide A.