Highly selective and direct electroreductive ring-opening carboxylation of epoxides with CO2 in an undivided cell to yield synthetically important β-hydroxy acids is described. CO2functions not only as a carboxylative reagent in this reaction but also as a promoter to enable efficient and chemoselective transformation of epoxides under additive-free electrochemical conditions.
描述了在未分裂的电池中用 CO 2对环氧化物进行高选择性和直接的还原性开环羧化,以产生合成重要的β-羟基酸。CO 2不仅在该反应中充当羧化试剂,而且还充当促进剂以在无添加剂的电化学条件下实现环氧化物的有效和化学选择性转化。
Cyclization of dimethyl oxalate upon electron impact
作者:J. G. Liehr、E. A. Larka、J. H. Beynon
DOI:10.1002/oms.1210160110
日期:1981.1
AbstractIsotope labelling experiments and also consecutive fragmentation investigations of metastable ions, a novel technique in mechanistic studies, have been carried out to elucidate structure and genesis of the m/z 45 ions from dimethyl oxalate as well as dimethyl carbonate. It is shown that the formation of the m/z 45 ions, \documentclassarticle}\pagestyleempty}\begindocument}$ \rmCH}}_\rm3}} \mathop \rmO}}\limits^\rm + }} = \rmCH}}_\rm2}} $\enddocument}, in the mass spectra of these compounds arises via single step processes. Mechanisms involving hydrogen transfer and subsequent formation of cyclic intermediates which then collapse to give \documentclassarticle}\pagestyleempty}\begindocument}$ \rmCH}}_\rm3}} \mathop \rmO}}\limits^\rm + }} = \rmCH}}_\rm2}} $\enddocument} directly from molecular ions are suggested. No evidence was found for a two‐step fragmentation route to m/z 45 from the molecular ions of either dimethyl oxalate or dimethyl carbonate.