Generation of Carbamoyl- and Thiocarbamoyllithium Synthons Having a Hydrogen(s) or an Aryl Group on the Nitrogen and Their Trapping with Carbonyl Electrophiles
摘要:
Dimetalated amides 1 (Y = O) were generated as the synthons of carbamoyllithiums 2 (Y = O) by the reaction of isocyanates with iBu2AlTenBu and a subsequent tellurium-lithium exchange reaction. A series of amide derivatives 3 (Y = O) were obtained by the trapping of dianion 1 with electrophiles. This transformation can be successfully applied to the generation and trapping of thiocarbamoyllithium synthons 1 (Y = S) as well as to the nucleophilic introduction of the parent carbamoyl moiety H2NC(O).
A chemoselective reduction of α‐keto amides to biologically important α‐hydroxy amides (mandelamides) by polymethylhydrosiloxane (PMHS) using 5 mol% potassium phosphate (K3PO4) as catalyst has been developed. This transition metal‐free protocol discloses excellent chemoselectivity for the ketone reduction of α‐keto amides in the presence of other reducible functionalities like ketone, nitro, halides
已开发出使用5 mol%磷酸钾(K 3 PO 4)作为催化剂,通过聚甲基氢硅氧烷(PMHS)将α-酮酰胺化学选择性还原为生物学上重要的α-羟基酰胺(扁桃酰胺)的方法。该无过渡金属方案公开了在存在其他可还原官能团(例如酮,硝基,卤化物,腈和酰胺)的情况下,α-酮酰胺的酮还原反应具有出色的化学选择性。此外,化学选择性还原的α-羟基酰胺已被衍生为无异氰酸酯的Passerini加合物。所述Ñ烷基-α羟基酰胺已经通过用甲磺酰cholride和三乙胺处理被成功地转化为3- phenyloxindole衍生物。
Catalyst- and Additive-Free Chemoselective Transfer Hydrogenation of α-Keto Amides to α-Hydroxy Amides by Sodium Formate
A catalyst‐ and additive‐free chemoselective transfer hydrogenation of α‐keto amides to α‐hydroxy amides is easily achieved by using sodium formate as a hydrogen source. Control experiments suggest that the NH group of α‐keto amides is crucial for the chemoselective reduction through the formation of hydrogen bonds.
Zinc salt-catalyzed reduction of α-aryl imino esters, diketones and phenylacetylenes with water as hydrogen source
作者:Guoli Shen、Haojie Liu、Jingchao Chen、Zhenxiu He、Yongyun Zhou、Lin Wang、Yang Luo、Zhimin Su、Baomin Fan
DOI:10.1039/d1ob00155h
日期:——
The zinc salt-catalyzed reduction of α-aryl imino esters, diketones and phenylacetylenes with water as hydrogen source and zinc as reductant was successfully conducted. The presented method provides a low-cost, environmentally friendly and practical preparation of α-aryl amino esters, α-hydroxyketones and phenylethylenes. By using D2O as deuterium source, the corresponding products were obtained in
Chemoselective reduction of α-keto amides using nickel catalysts
作者:N. Chary Mamillapalli、Govidasamy Sekar
DOI:10.1039/c4cc02744b
日期:——
Ni-catalysts are used for the first time to synthesize α-hydroxy amides and β-amino alcohols from α-keto amides by chemoselective and complete reduction using hydrosilanes.
An efficient and practical method for chemoselective “on-water” reduction of α-keto amide by Hantzschester without using any catalysts and additives was developed. Control experiments indicated that the intramolecular hydrogen bond of α-keto amide was crucial for this transformation. A variety of α-hydroxy amides were prepared in high yields in an environmentally friendly way.