Stereotriads bearing
allylic alcohols are privileged structures
in natural products, and new methods accessing these in a stereoselective
fashion are highly sought after. Toward this goal, we found that the
use of chiral polyketide fragments allows for 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. The switch of directing groups in most cases resulted in
the reversed stereochemical outcome, which could be explained by conformational
analysis on density functional theory level and a Felkin-like model.