CATALYTIC ENANTIOSELECTIVE CARBON-CARBON BOND FORMATION BY ADDITION OF DIALKYLZINC REAGENTS TO CYCLIC 1,3-DIENE MONOEPOXIDES

Chiral copper complexes of 2,2'-binaphthyl-based phosphorus amidites a re shown to be highly effective catalysts for the conjugate addition o f dialkylzinc reagents to vinyloxiranes. The corresponding allylic alc ohol reaction products (S(N)2'-pathway) were obtained with moderate to high regioselectivity. Both direct- (S(N)2-pathway) and conjugate-ope ning addition (S(N)2'-pathway) seem to proceed with complete anti ster eoselectivity. The enantioselectivity of these addition reactions acco rding to a kinetic resolution protocol turned out to be high (>90% ee) with 1,3-cyclohexadiene and 1,3-cycloheptadiene monoepoxides. (C) 199 8 Elsevier Science Ltd. All rights reserved.