Stereoselective Synthesis of (<i>E</i>)- or (<i>Z</i>)-α-Alkylidene-γ-butyrolactone from γ-Butyrolactone and Bis[ethoxy(thiocarbonyl)] Disulfide and Mechanistic Studies of the Effect of Metal Complexes on the Stereoselection
作者:Syuichi Matsui
DOI:10.1246/bcsj.60.1853
日期:1987.5
with an aldehyde to afford exclusively (E)-α-alkylidene-γ-butyrolactone. Interestingly, when the reaction was quenched below −20 °C or when it was carried out in the presence of metal complex such as zinc chloride, copper(I) iodide, or tributyltin chloride, (Z)-α-alkylidene-γ-butyrolactone was obtained as the major product. The stereoselectivity of this reaction was sensitive to the reaction temperature
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.
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