Conjugate Allylation to alpha,beta-Unsaturated Aldehydes with the New Cbemzyme p-F-ATPH

摘要

Conjugate allylation to alpha,beta-unsaturated aldehydes is an extremely difficult, hitherto unattainable transformation in organic synthesis, and no effective procedure has yet been developed to a useful level due to the lack of a satisfactory reagent. Even organocopper reagents, which have been employed successfully in the conjugate alkylation to alpha,beta-unsaturated car-bonyl compounds, gave very disappointing results for the conjugate allylation. For instance, the reaction of cinnamalde-hyde with allylcopper or lithium diallylcuprate gave predominantly the 1,2-adduct trans-l-phenyl-l,5-hexadien-3-ol (Scheme 1). Our recently developed new conjugate alkylation procedure with the Lewis acidic receptor aluminum tiis(2,6-diphenylphenoxide) (ATPH) was also found to be less effective for the present conjugate allylation, and only the ATPH/al-lyllithium system gave modest 1,4-selectivity (Scheme 1).