New Methods for Stereoselective Synthesis of α-Alkylidene-γ-butyrolactones Using Monoanion of<i>O</i>-Ethyl<i>S</i>-(Tetrahydro-2-oxo-3-furanyl) Thiocarbonate and Dianion of α-Mercapto-γ-butyrolactone
The lithium enolates of O-ethyl S-(tetrahydro-2-oxo-3-furanyl) dithiocarbonate and thiocarbonate were found to be efficient reagents for the stereoselective synthesis of α-alkylidene-γ-butyrolactones fromcarbonylcompounds. The dianion of α-mercapto-γ-butyrolactone was successfully generated by treatment of α-mercapto-γ-butyrolactone with 2.2 equivalents of lithium diisopropylamide in the presence
A SIMPLE, STEREOCONTROLLED SYNTHESIS OF α-ALKYLIDENE-γ-BUTYROLACTONES
作者:Kazuhiko Tanaka、Norikazu Tamura、Aritsune Kaji
DOI:10.1246/cl.1980.595
日期:1980.5.5
Treatment of γ-butyrolactone with bis[methoxy(thiocarbonyl)] disulfide in the presence of 2.2 equivalents of lithium diisopropylamide followed by the addition of aldehydes gave predominantly (E)-α-alkylidene-γ-butyrolactones. In contrast, when the reaction was carried out in the presence of metal salt such as cuprous iodide or zinc chloride, (Z)-α-alkylidene-γ-butyrolactone was obtained as the major