Stereocontrol in the intramolecular Buchner reaction of diazoamides and diazoesters

Dirhodium(II) catalysed decomposition of diazoamide 5 resulted in formation of beta-lactams 6/7 by intramolecular C-H insertion, the intramolecular Buchner reaction being disfavoured for conformational reasons. The diazoamide 8, however gave products resulting from both the intramolecular Buchner reaction and C-H insertion. Chiral diazoesters 14-16 derived from a-substituted benzyl alcohols gave cycloheptatrienes in a highly diastereoselective manner; the norcaradiene isomer of the cycloheptatrienes was readily intercepted in a Diels-Alder reaction with 4-phenyl-1,2,4-triazoline-3.5-dione to give adducts 19-21.