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
Stereoselective synthesis of α-alkylidene- and substituted alkylidene-γ-lactones
作者:Jakub Častulı́k、Ctibor Mazal
DOI:10.1016/s0040-4039(00)00252-5
日期:2000.4
Cross-coupling reactions of (E)- and (Z)-tosylates of α-hydroxymethylene-γ-butyrolactone with aryl, heteroaryl, alkyl, and alkynylzinc chlorides under Pd(PPh3)4 catalysis were found to be a suitable synthetic method for stereoselective preparation of α-alkylidene- and substituted alkylidene-γ-lactones. The reactions, conducted under mild conditions, proceed with high stereoselectivity and moderate yields.