Enantioselective Decarboxylative Alkylation of β-Keto Acids to ortho-Quinone Methides as Reactive Intermediates: Asymmetric Synthesis of 2,4-Diaryl-1-benzopyrans.

A novel and efficient asymmetric synthesis of 2,4-diaryl-1-benzopyrans via enantioselective decarboxylative alkylation of β-keto acids to o-QM intermediates, followed by sequential cyclization and dehydration, has been developed. The synthetically useful chiral 2,4-diaryl-1-benzopyran derivatives were obtained in moderate to high yields and high enantioselectivities through a one-pot, two-step sequence. This approach offers a facile way to prepare chiral 2,4-diaryl-1-benzopyran derivatives with a wide range of functional group tolerance.