Amine-Promoted Three-Component Cycloaddition of Bicyclo[1.1.0]butanes with Hydroxylamine and Polyformaldehyde Expedient Access to 2-Oxa-3-azabicyclo[3.1.1]heptanes

Bicyclo[3.1.1]heptanes are generally considered important bioisosteres for meta-substituted arenes. Herein, we have developed an amine-promoted synthesis of C4-unsubstituted 2-oxa-3-azabicyclo[3.1.1]heptanes via formal dipolar [4π+2σ] cycloaddition of bicyclo[1.1.0]butanes (BCBs) with nitrones generated...