Stereoselective Synthesis of Alcohols, XXIX. Addition of (α‐Methoxycrotyl)boronates to Aldehydes

Abstract α‐Phenoxy‐ (4) and α‐methoxycrotylboronates (8) were obtained from the α‐chlorocrotylboronates 1. Addition of the phenoxy compound to aldehydes gave the homoallyl alcohols 5/6 as Z/E mixtures; addition of the methoxy compound 8 led to essentially pure Z‐enol ethers 9. Enantiomerically enriched (ca. 90% e.e.) 8 was used in reactions with chiral aldehydes to ensure the formation of the new stereogenic centers under reagent control of diastereoselectivity.