Catalytic asymmetric arylation of N-substituted 2-pyrrolines with aryl triflates
作者:Fumiyuki Ozawa、Tamio Hayashi
DOI:10.1016/0022-328x(92)83236-b
日期:1992.4
Catalyticasymmetricarylation of 1-(alkoxycarbonyl-2-pyrrolines (4) with aryltriflates (1) in benzene in the presence of a base and a palladium catalyst, prepared in situ by mixing Pd(OAc)2 and (R)-BINAP, gives optically active (R-1-(alkoxycarbonyl-5-aryl-2-pyrrolines (5) of up to 83% ee, together with the regioisomers 1-(alkoxycarbonyl)-5-aryl-3-pyrrolines (6).
Palladium complexes with chiral phosphinooxazoline ligands are efficient catalysts for enantioselective Heck reactions with aryl or alkenyl triflates and cyclic alkenes. In the arylation and alkenylation of 1,2-dihydrofuran, cyclopentene, 2,3-dihydro-4H-pyran, 4,7-dihydro-1,3-dioxepin, and N-methoxycarbonyl-2,3-dihydropyrrole high yields and good to excellent enantioselectivities have been obtained. In contrast to analogous (BINAP)Pd-catalyzed reactions, isomerization of the products by C-C double bond migration was essentially not observed.