Ph3P+CH2R (R = H, Me) reacted with aldehydes R1CHO (R1 = n-C5H11, Me2PrC, Ph) in the presence of BuLi and HCHO to give primary alkenols R1CH:CRCH2OH; ketones R2R3CO [R2, R3 = Me, Ph or (CH2)4, (CH2)5] and spatially crowded aldehydes gave secondary and tertiary alcs. R2R3C(OH)CR:CH2. A b-oxido phosphonium ylide was a reaction intermediate. [on SciFinder (R)]