Thermodynamically controlled deracemization of some acyclic ketones bearing a chiral center at the position α to the carbonyl group was satisfactorily achieved. Acyclic ketones with high optical purities could be isolated after treatment of the racemic ketones with base in aqueous MeOH in the presence of (–)-(2R,3R)-trans-2,3-bis(hydroxydiphenylmethyl)-1,4-dioxaspiro[5.4]decane (1a). The efficiency
Bifunctional chiral auxiliaries 6: Alkylations of enolates derived from 1,3-diacylimidazolidine- 2-thiones and 1,3-diacylimidazolidin-2-ones
作者:Stephen G. Davies、Gary B. Evans、Andrew A. Mortlock
DOI:10.1016/0957-4166(94)80022-7
日期:1994.4
Sodium and potassium enolates of 1,3-diacylimidazolidin-2-ones undergo clean alkylationreactions with reactive alkylhalides; the latter enolates reacting generally more stereoselectively due, it is proposed, to the lower temperature at which the reactions proceed. The reactions are all stereoregular, with the diastereoisomeric identity of products being established unambiguously by the synthesis
The invention relates to substituted [(phenylethanoyl)amino]benzamides and methods for their preparation, and their use for the manufacture of medicaments for the treatment and/or prophylaxis of diseases, in particular of inflammatory disorders such as, for example, cutaneous, respiratory tract and cardiovascular disorders such as, for example, arteriosclerosis and coronary heart disease.
carbon-containing cyclobutane-1,3-diones using chiral phosphoric acid catalysis and commercially available oxidants was reported. According to the structure of the substrates, two optimized reaction conditions were developed to afford the corresponding chiral tetronic acid products in ≤93% and ≤95% ee values. This reaction offers the first catalytic asymmetric approach to chiral 5,5-disubstituted tetronic acid derivatives
首次报道了使用手性磷酸催化和市售氧化剂对含季碳环丁烷-1,3-二酮进行高度对映选择性拜耳-维利格氧化。根据底物的结构,开发了两种优化的反应条件,得到了相应的手性季酮酸产物,其ee值≤93%和≤95%。该反应为手性 5,5-二取代特窗酸衍生物提供了第一个催化不对称方法。(−)-vertinolide 的正式不对称合成和 plakinidone B 的首次催化不对称全合成证明了该方法的合成潜力。
Bifunctional chiral auxiliaries 2: the synthesis of 1,3-diacylimidazolidin-2-ones from 1,2-diamines
作者:Stephen G. Davies、Andrew A. Mortlock
DOI:10.1016/s0040-4039(00)92309-8
日期:1991.1
The title compounds are readily prepared in three steps via the corresponding 1,3-diacylimidazolidine-2-thiones. The final step involves the novel use of mercury (II) acetate for the conversion of thioureas to ureas.