FACILE AND HIGHLY STEREOSELECTIVE SYNTHESIS OF HOMOALLYLIC ALCOHOLS USING ORGANOSILICON INTERMEDIATES

Allyltrichlorosilanes regioselectively reacted with aldehydes in N,N-dimethylformamide (DMF) without a catalyst to afford the corresponding homoallylic alcohols in high yields. The reactions proceeded under neutral conditions, and syn- and anti-homoallylic alcohols were stereoselectively obtained from (Z)- and (E)-allyltrichlorosilanes, respectively. In these reactions, DMF coordinated to the silicon atom of the allyltrichlorosilanes to form hypervalent silicates, which in turn reacted with aldehydes smoothly. Solvent effects in these reactions were also examined. The reactions were applied to the one-pot synthesis of homoallylic alcohols from allylic chlorides via organosilicon intermediates. While syn-homoallylic alcohols were prepared from (Z)-allyl chlorides, antihomoallylic alcohols were obtained from (E)-allyl chlorides. Unique regioselectivities in the reactions of 1-chloro-2,4-pentadiene were also found. Finally, the one-pot synthesis of homoallylic alcohols from 1,3-dienes is reported.