B-Allyldiisopinocampheylboranes [18, prepared from (+ Ia-pinene; 19, prepared from (-)-a- pinene] have been screened for diastereofacial selectivity in their reaction with a-substituted chiral aldehydes. Both syn and anti products have been obtained in very high diastereoselectivities. Further,(E)-crotyldiisopinocampheylboranes [20, prepared from (+)-a- pinene; 21, prepared from (-)+ pinene] and (2)-crotyldiisopinocampheylboranes[22, ...
