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

Nitro versus nitro: 4‐Nitro‐5‐styrylisoxazoles were used as masked α,β‐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 (see scheme).