A New Method for the Preparation of Michael Adducts and Cyclic Enones Using Lithium Chloride-Hexamethylphosphoramide System.
作者:Yutaka OZAKI、Ayako KUBO、Kyouko OKAMURA、Sang-Won KIM
DOI:10.1248/cpb.43.734
日期:——
A new procedure using lithium chloride in hexamethylphosphoramide was found to be useful for the synthesis of Michael-type adducts and cyclic enones. Selectivity for the two products could be controlled by altering the reaction temperature employed. The urea-type solvents were also examined instead of hexamethylphosphoramide.
Allylation with substituted vinylthionium ions from SnCl4 ionisation of 1,3- and 3,3-bis(alkyl/phenylthio) propenes
作者:Roger Hunter、Joseph P. Michael、Daryl S. Walter
DOI:10.1016/s0040-4020(01)85514-9
日期:——
α- and γ-substituted vinylthionium ions from SnCl4 ionisation of a range of substituted 1,3- and 3,3-bis (alkyl/phenylthio) propenes allylate enol allyl ethers in good yield. Levels of regioselectivity are sterically dependent and in the case of methyl as γ-substituent may be controlled by the steric bulk of the sulfur substituent. As with the Pummerer methodology, γ-addition generally gave (E)-vinyl
Alkylation of enol silyl ethers with vinylthionium ions generated from 1,1- and 1,3-bis(phenylthio)propenes.
作者:Roger Hunter、Joseph P. Michael、Daryl S. Walter
DOI:10.1016/s0040-4039(00)79108-8
日期:1992.9
Vinylthioniumions generated from 1,1- and 1,3-bis-(phenylthio) propenes alkylate enolsilylethers regioselectively under mild reaction conditions with tin tetrachloride.
A Novel Tandem [2 + 2] Cycloaddition−Dieckmann Condensation with Ynolate Anions. Efficient Synthesis of Substituted Cycloalkenones and Naphthalenes via Formal [<i>n</i> + 1] Cycloaddition
作者:Mitsuru Shindo、Yusuke Sato、Kozo Shishido
DOI:10.1021/jo015929w
日期:2001.11.1
A noveltandem [2 + 2] cycloaddition-Dieckmanncondensation via ynolate anions is described. Ynolate anions are useful for the formation of reactive beta-lactone enolates via a pathway not involving the enolization of the corresponding beta-lactones. The [2 + 2] cycloaddition of ynolate anions with delta- or gamma-keto esters, followed by Dieckmann condensation, gives bicyclic beta-lactones, which
A Method for the Cyclic Enone Synthesis Using Lithium Chloride – Hexamethylphosphoramide System
作者:Yutaka Ozaki、Ayako Kubo、Sang-Won Kim
DOI:10.1246/cl.1993.993
日期:1993.6
Cyclic enones were obtained from the reactions of β-keto esters with acyclic α,β-unsaturated ketones by using lithium chloride in hexamethylphosphoramide. The products were brought about via the Michael addition, decarboxylation, and the aldol condensation.