2002 Alcohols

AlcoholsQ 0230 Regio- and Stereoselective Synthesis of Homoallylic Alcohols Based on the Use of

(3-Chloroprop-1-en-1-yl)boronates. — A novel method for the regio- and stereose-lective synthesis of homoallylic alcohols is presented, involving the application of cyclic chloropropenylboronates in a vinylogous Matteson-type reaction with Grignard reagents. This reaction provides access to α-substituted allylboronates, which can un-dergo a 1,3-boratropic shift to furnish γ-substituted allylboronates. The extent of rear-rangement reaction depends on the reaction temperature, but is mainly determined by the nature of cyclic boronate. Quenching of the reaction mixture with aldehydes then affords two regioisomers of homoallylic alcohols (IX) and (VII)/(VIII). The E/Z-selec-tivity in regioisomers (VII)/(VIII) is proposed to be determined by the nature of migrat-ing group. — (LOMBARDO*, M.; MORGANTI, S.; TOZZI, M.; TROMBINI, C.; Eur. J. Org. Chem. 2002, 16, 2823-2830; Dip. Chim. "G. Ciamician", Univ. Bologna, I-40126 Bologna, Italy; Eng.) — Mischke

01- 079

2002 Alcohols