PHOTOINDUCED ELECTRON TRANSFER-INITIATED CYCLIZATION REACTIONS AND ASYMMETRIC TRANSFORMATIONS OF (Z)-α-DEHYDROAMINO ACID DERIVATIVES

摘要

We systematically investigated the cyclization reactions of N-acyl-α-dehydroamino acid derivatives, initiated by electron transfer (ET) from aliphatic amines to these derivatives in the excited state. On the basis of the percent conversion of the starting a-dehydroamino acid and the composition of the cyclization products, we demonstrated that the photoinduced ET reactions of N-acyl-α-dehydroarylalaninamides, 1,2,4-triazole-substituted a-dehydro-arylalaninamides, and N-acyl-α-dehydroarylalanine alkyl esters efficiently proceeded to afford various 3,4-dihydroquinolinone; quinolinone; and 4,5-dihydrooxazole derivatives, respectively, with high selectivities. In addition, the introduction of chiral auxiliary groups into N-acyl-α-dehydroamino acid amide and ester derivatives and the presence of chiral aliphatic amines induced efficient diastereoselective and enantioselective photocyclization reactions of these amide and ester derivatives, respectively, to enable the construction of the chiral dihydroquinolinone and dihydrooxazole rings.