(−)-O,O′-di-pivaloyl-L-tartaric acid in tetrahydrofuran T=-70°C; 15 h; e.e. of product varying reaction time and temperature (-70 to 20 deg C); Product distributionMechanism;

(−)-O,O′-di-pivaloyl-L-tartaric acid in tetrahydrofuran T=-70°C; 15 h; e.e. of product varying reaction time and temperature (-70 to 20 deg C); Product distributionMechanism;

(−)-O,O′-di-pivaloyl-L-tartaric acid; triethylamine 1.), 2.) THF, -70 deg C; Multistep reaction;