Enantioselective Synthesis of (E)‐δ‐Boryl‐Substituted anti‐Homoallylic Alcohols Using Palladium and a Chiral Phosphoric Acid

(E)‐δ‐Boryl‐substituted anti‐homoallylic alcohols are synthesized in a highly diastereo‐ and enantioselective manner from 1,1‐di(boryl)alk‐3‐enes and aldehydes. Mechanistically, the reaction consists of 1) palladium‐catalyzed double‐bond transposition of the 1,1‐di(boryl)alk‐3‐enes to 1,1‐di(boryl)alk‐2‐enes, 2) chiral phosphoric acid catalyzed allylation of aldehydes, and 3) palladium‐catalyzed geometrical isomerization from the Z to E isomer. As a result, the configurations of two chiral centers and one double bond are all controlled with high selectivity in a single reaction vessel. TRIPping: The title alcohols are synthesized in a highly diastereo‐ and enantioselective manner from 1,1‐di(boryl)alk‐3‐enes and aldehydes by the concomitant use of [{Pd(μ‐Br)(PtBu3)}2] and chiral phosphoric acid (R)‐TRIP. The reaction proceeds by a double‐bond transposition/aldehyde allylboration/E/Z isomerization sequence.