A facile and general sequential elimination/reduction process promoted by samariumdiiodide provides an efficient method for synthesizing saturated esters or amides 3 from readily available starting materials. The reaction involves a beta-elimination of the starting 2-halo-3-hydroxyesters or -amides 1 and subsequent 1,4-reduction of the obtained alpha,beta-unsaturated esters or amides in the presence
ALKYLATION REACTION ACCOMPANIED BY DEALKOXYCARBONYLATION OF β-KETO ESTERS, GEMINAL DIESTERS AND α-CYANO ESTER IN HEXAMETHYLPHOSPHORIC TRIAMIDE (HMPA)
作者:Morio Asaoka、Kazutoshi Miyake、Hisashi Takei
DOI:10.1246/cl.1975.1149
日期:1975.11.5
In the presence of alkali halide β-keto esters, geminal diesters and ethyl cyanoacetate in HMPA reacted with alkyl halides to give α-alkylated ketones, esters and nitrile, respectively. α-Acetyl-γ-butyrolactone and its derivative afforded corresponding acylcyclopropane derivatives.
Radicals produced via the indirect reduction of alkyl halides by aromatic radical anions are likely to couple fast with the mediator. In the presence of activated olefins or good hydrogen atom donors the fate of the alkyl radicals might be changed. In this study rate constants for the coupling reaction (2) between primary, secondary and tertiary alkyl radicals and some aromatic radical anions were measured via the competition with addition of the radical to styrene or ethyl cinnamate, or via the competition with hydrogen atom transfer from thiophenol or 2-methyl-2-propanethiol to the alkyl radical. It is shown that for all the alkyl radicals and aromatic radical anions investigated so far the rate constant for coupling is close to 1 x 10(9) M-1 s(-1).
Synthesis of 2,3-dideuterioesters from 2-halo-3-hydroxyesters by using metallic samarium and diiodomethane
作者:José M Concellón、Mónica Huerta
DOI:10.1016/s0040-4039(02)00950-4
日期:2002.7
2,3-Dideuterioesters are obtained in high yield from 2-chloro-3-hydroxyesters by a sequenced elimination;reduction process promoted by samarium diiodide generated in situ from metallic samarium and diiodomethane. (C) 2002 Elsevier Science Ltd. All rights reserved.