A Highly Site‐, Regio‐, and Stereoselective Lewis Acid Catalyzed Formal [3+3] Cycloaddition of Methylenecyclopropane‐1,1‐Diesters with C,N‐Diarylnitrones
State Key Laboratory of Elemento‐Organic Chemistry, Institute of Elemento‐Organic Chemistry, Nankai University, Tianjin 300071 (China), Fax: (+86)?22‐23498191