The Ti-mediated reaction of Grignard reagents with nitriles was investigated with sub-stoichiometric amounts of titanium isopropoxide. Cyanoesters were converted to spirocyclopropanelactams in good yields using as low as 0.05 eq of Ti(OiPr)4. Under similar conditions, cyanocarbonates led to spirocyclopropane oxazolidinones and/or aminocyclopropylcarbinols. A very short synthesis of the naturally occurring aminocyclopropanecarboxylic acid illustrates the usefulness of this methodology.
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.