Acylative Desymmetrization of Cyclic <i>meso</i>-1,3-Diols by Chiral DMAP Derivatives
作者:Hiroki Mandai、Tsubasa Hironaka、Koichi Mitsudo、Seiji Suga
DOI:10.1246/cl.200809
日期:2021.3.5
An efficient enantioselective acylative desymmetrization of cyclic meso-1,3-diols was developed by using a chiral DMAP derivative 1e having a 1,1′-binaphthyl unit. The reactions required only 0.5 m...
A One-Pot, Base-Free Annelation Approach to α-Alkylidene-γ-butyrolactones
作者:Russell R. A. Kitson、Richard J. K. Taylor、John L. Wood
DOI:10.1021/ol902191d
日期:2009.11.19
A novel annelation procedure has been developed for the conversion of γ-hydoxy enones into α-alkylidene-γ-butyrolactones. This one-pot method utilizes the Bestmann ylide (triphenylphosphoranylideneketene) and proceeds by way of acylation followed by an intramolecular conjugate addition/proton transfer/Wittig olefination sequence. The procedure is “base-free” and is useful for the preparation of a range
(+)- and (-)-5,5-Dimethyl-4-hydroxy-2-cyclopentenone 1 were efficiently synthesized by the dissymmetrization of meso diol 2 with lipase-catalyzed acetylation as a key step. The synthesis of (+)-5,5-dimethyl-4-hydroxy-2-cyclopentenone was also carried out by the chemical conversion of (-)-pantolactone 6.
A convenientsynthesis of 4-hydroxy spiro[4.n]alk-2-ene-1-ones and spiro [4.n]alk-2-ene-1,4-diones, which involves the intramolecular acylation of α-sulfinyl carbanions followed by pyrolysis and/or oxidation, is described.
The Preparation of α-Alkylidene-γ-Butyrolactones Using a Telescoped Intramolecular Michael/Olefination (TIMO) Sequence: Synthesis of (+)-Paeonilactone B
作者:Michael G. Edwards、Martin N. Kenworthy、Russell R. A. Kitson、Alexis Perry、Mark S. Scott、Adrian C. Whitwood、Richard J. K. Taylor
DOI:10.1002/ejoc.200800558
日期:2008.10
A novel telescopedintramolecularMichael addition/proton transfer/HWE olefination sequence has been developed to provide rapid access to α-alkylidene-γ-butyrolactones. This methodology has been applied to prepare a range of tetrahydrobenzofuran-2,5-diones, and related systems, and also utilised in an extremely short synthesis of the natural product (+)-paeonilactoneB in enantiomerically pure form