[2+2] Photocycloaddition of 3-Alkenyloxy-2-cycloalkenones: Enantioselective Lewis Acid Catalysis and Ring Expansion
作者:Richard Brimioulle、Thorsten Bach
DOI:10.1002/anie.201407832
日期:2014.11.17
(50 mol %) of a chiral Lewisacid, the intramolecular [2+2] photocycloaddition of the title compounds was achieved with high enantioselectivity (up to 94 % ee). Upon cleavage of the cyclobutane ring the resulting tricyclic products underwent ring‐expansion reactions under acidic conditions and formed anellated seven‐ or eight‐membered‐ring systems without racemization. The ringexpansion could be combined