Stereoselective Synthesis of Allylic Alcohols via Substrate Control on Asymmetric Lithiation

Allylic alcohols are a privileged motif in natural product synthesis and new methods that access them in a stereoselective fashion are highly sought after. Toward this goal, we found that chiral acetonide‐protected polyketide fragments performing the Hoppe–Matteson–Aggarwal rearrangement in the absence of sparteine with high yields and diastereoselectivities rendering this protocol a highly valuable alternative to the Nozaki–Hiyama–Takai–Kishi reaction. Various stereodyads and ‐triads were investigated to determine their substrate induction. The mostly strong inherent stereoinduction was attributed to a combination of steric and electronic effects. Sparteine free Hoppe–Matteson–Aggarwal rearrangement was applied to various chiral acetonides. Utilizing different vinyl boronic esters a high level of substrate control was observed leading to excellent selectivities. These selectivities were attributed to stereoelectronic effects of the neighboring acetonide moiety. The obtained formal Felkin and anti‐Felkin products feature up to four contiguous stereocenters representing structural motifs common in natural products.