Synthesis of Tetrasubstituted and Functionalized Enol Ethers by E-Selective Olefination of Esters with Ynolates
摘要:
We have developed the E-selective olefination of ester carbonyls to afford tetrasubstituted, functionalized olefins and the C-S insertion of thiol esters to give beta-keto thiol esters via ynolates.
我们开发了一种使用带有磺酸部分的两亲性整体树脂作为阳离子交换功能(整体-SO 3 H)将羧酸与醇酯化的方法。Monolith-SO 3 H 在 60–80 °C 下,在甲苯中有效地催化芳香族和脂肪族羧酸与各种伯醇和仲醇(1.5–5.0 当量)的酯化反应,无需去除反应过程中产生的水。Monolith-SO 3的两亲性H 由于其吸水能力而促进脱水。该反应也适用于硫酯化,尽管需要在 120 °C 下加热,但仅使用 2.0 当量的硫醇在甲苯中即可以优异的收率获得相应的硫酯。此外,整体式-SO 3 H 可通过简单的过滤从反应混合物中分离出来,并在不降低催化活性的情况下重复使用至少五次。
Methods for directfunctionalization of C–H bonds mediated by N-oxyl radicals constitute a powerful tool in modern organic synthesis. While several N-oxyl radicals have been developed to date, the lack of structural diversity for these species has hampered further progress in this field. Here we designed a novel class of N-oxyl radicals based on N-hydroxybenzimidazole, and applied them to the direct C–H functionalization
NHC-catalyzed thioesterification of aldehydes by external redox activation
作者:Takuya Uno、Tsubasa Inokuma、Yoshiji Takemoto
DOI:10.1039/c2cc17183j
日期:——
The NHC-catalyzed thioesterification of aromatic or aliphatic aldehydes with a range of thiols was developed in the presence of a stoichiometric amount of an organic oxidant. Among the oxidants examined, phenazine was shown to give the best results in terms of chemical yield and compatibility with thiols.
Direct thioesterification from carboxylic acids and thiols catalyzed by a Brønsted acid
作者:Shinya Iimura、Kei Manabe、Shū Kobayashi
DOI:10.1039/b109834a
日期:2002.1.14
In the presence of a catalytic amount of trifluoromethanesulfonic acid, free carboxylic acids reacted with free thiols directly to afford the corresponding thioesters in high yields.
copper-mediated ketonesynthesis could be applied to the synthesis of not only gluconolactone-derived ketone 6, a synthetic intermediate in the transformation to the SGLT2 inhibitor canagliflozin, but also thiolactol 8, a valuable synthetic intermediate for (+)-biotin. Control experiments on an isolated diphenylcuprate(I), [CuPh2 ]- (12), and DFT calculations revealed that this ketonesynthesis proceeded