Intramolecular Diels-Alder (IMDA) reactions of 2-pyrones containing an alkyne tether occur with remarkably high diastereofacial selectivity to provide medium-sized macrolactones. Because of the strain in the alkyne-tethered macrocyclic system, a single methyl group in the tether provides sufficient conformational bias to generate medium-sized macrocycles with unusually high selectivity.
Combined microbial oxidation and reduction: a new approach to the highyield synthesis of homochiral unsaturated secondary alcohols from racemates
摘要:
The oxidation of racemic secondary alcohols with Bacillus stearothermophilus followed by reduction of the mixture with Yarrowia lipolytica to afford high yields of the enantiomerically pure R-alcohols la,b,d is described. Comparisons with Yarrowia lipolytica reduction, Bacillus stearothermophilus oxidation, and the contemporary use of the two microrganisms have been made.