Catalytic Asymmetric Conjugate Addition of Nitroalkanes to 4-Nitro-5-styrylisoxazoles

Nitro versus nitro: 4-Nitro-5-styrylisoxazoles were used as masked ?,?-unsaturated carboxylic acids in the titled catalytic asymmetric transformation. The 4-nitroisoxazole core acts as an activator of the conjugated alkene and a latent carboxylate functionality. The reaction proceeded with 5 mol % of a readily prepared phase-transfer catalyst at room temperature with remarkable diastereo- and enantioselectivity.