Highly stereoselective synthesis of 2,3-dihydrofurans via a cascade Michael addition-alkylation process: a nitro group as the leaving group.

The Michael addition-alkylation process between gem-benzoyl-nitrostyrenes and 1,3-dicarbonyl compounds proceeded smoothly in the presence of a bifunctional squaramide, exclusively providing 2,3-dihydrofurans as trans-diastereomers in 33-92% isolated yields and excellent enantioselectivities (29->99% ee).