Highly enantioselective [3+2] annulation of 4-amino-isoxazoles with quinone monoimines to access structurally diverse isoxazoline fused dihydrobenzofurans and antifungal evaluation

Abstract

The first catalytic enantioselective [3+2] cyclization between 4-amino-isoxazoles and quinone monoimines was achieved by using a chiral phosphoric acid catalyst. This transformation afforded a series of isoxazoline fused dihydrobenzofuran derivatives with two sequential chiral centers in high yields and outstanding enantioselectivities. The absolute configuration of the title compounds was determined by X-ray crystal structure analysis. The subsequent application of the obtained products displayed good antifungal activity against five plant pathogenic fungi further demonstrates the versatility of this transformation.This approach provided an excellent alternative strategy for the synthesis of corresponding bioactive molecules containing an isoxazoline fused dihydrobenzofurans skeleton.