Organocatalytic Synthesis of α‑Trifluoromethyl Allylboronic Acids by Enantioselective 1,2-Borotropic Migration

Chiral α-substituted allylboronic
acids were synthesized
by asymmetric homologation of alkenylboronic acids using CF3/TMS-diazomethanes in the presence of BINOL catalyst and ethanol.
The chiral α-substituted allylboronic acids were reacted with
aldehydes or oxidized to alcohols in situ with a high degree of chirality
transfer. The oxygen-sensitive allylboronic acids can be purified
via their isolated diaminonaphthalene (DanH)-protected derivatives.
The highly reactive purified allylboronic acids reacted in a self-catalyzed
reaction at room temperature with ketones, imines, and indoles to
give congested trifluoromethylated homoallylic alcohols/amines with
up to three contiguous stereocenters.