Intermolecular Asymmetric Carboesterification of Alkenes by Using Chiral Amine Auxiliaries under O-2: Synthesis of Enantioenriched alpha-Methylene-gamma-Lactones through Chloropalladation of Alkynes

摘要

Herein, the first example of chloropalladation-initiated asymmetric intermolecular carboesterification of alkenes with alkynes by using chiral amine auxiliaries is reported. The use of (1S, 2S)-N-1,N-1-dimethylcyclohexane-1,2diamine auxiliaries is essential for providing a-methylene-gamma-lactones products in moderate to high yields and excellent enantioselectivities at room temperature. Moreover, the chiral amine auxiliaries can be readily removed by hydrolysis during the reaction process to keep the absolute configuration. This oxygen-and water-promoted asymmetric reaction opens a new window to study asymmetric processes in halopalladation reactions.