Ti-Mediated Chemoselective Conversion of Cyanoesters and Cyanoamides into β-Aminoesters and 1-Aza-spirolactams Bearing a Cyclopropane Ring.
作者:Jan Szymoniak、Philippe Bertus
DOI:10.1055/s-2003-36785
日期:——
α-Cyanoesters or tertiary α-cyanoamides react with Grignard reagents and Ti(i-PrO)4 to afford respectively β-amino esters or amides, bearing a cyclopropane ring. Starting from β- or γ-cyanoesters, spirocyclopropanelactams are formed via an in situ cyclopropanation-lactamization sequence.
The protection of 2-substituted imidazole-5-methanol derivatives by tert-BDMS allowed the chlorination of the heterocycle in position 4 with good yield whereas direct chlorination on the imidazole alcohol was unsuccessful.