Hydrophobic Polymer-Supported Catalyst for Organic Reactions in Water: Acid-Catalyzed Hydrolysis of Thioesters and Transprotection of Thiols
摘要:
A hydrophobic polystyrene-supported sulfonic acid was found to be effective for hydrolysis of thioesters in pure water. It was revealed that the catalyst was much superior to other Bronsted acid catalysts. Transprotection of thiols from thioesters to thioethers has been successfully performed in water using this catalytic system.
Pentafluorophenyl Esters: Highly Chemoselective Ketyl Precursors for the Synthesis of α,α-Dideuterio Alcohols Using SmI<sub>2</sub> and D<sub>2</sub>O as a Deuterium Source
作者:Hengzhao Li、Yuxia Hou、Chengwei Liu、Zemin Lai、Lei Ning、Roman Szostak、Michal Szostak、Jie An
DOI:10.1021/acs.orglett.9b04383
日期:2020.2.21
We report the first highly chemoselective synthesis of α,α-dideuterio alcohols with exquisite incorporation of deuterium (>98% [D2]) using pentafluorophenyl esters as ketyl radical precursors, SmI2 as a mild reducing agent, and D2O as the deuterium source. This system tolerates a variety of functional groups, offering rapid entry to valuable α,α-dideuterated alcohol building blocks. More generally
cathode surface, protonation, and radical cross-coupling process, resulting in a variety of valuable pyridine variants, which contain a tertiary and even a quaternary carbon at the α-position of pyridines, in high yields. The employment of thioesters to the conjugated alkenes enables no requirement of catalyst and high temperature, representing a highly sustainable synthetic method.
Malonylmethyl radical I [· CH2CH(COOEt)2] and its thioester analogue II [· CH2CH(COOEt) (COSEt)] were generated by standard photolytic and thermolytic methods from perester and bromo precursors. The structures of I and II were examined by ESR spectroscopy and found to exist in preferred conformations. However, no indication for their rearrangement by 1,2-shift of either an ethoxycarboxyl or (ethylthio)carbonyl
Nickel-Catalyzed Coupling of Arylzinc Halides with Thioesters
作者:Paul H. Gehrtz、Prasad Kathe、Ivana Fleischer
DOI:10.1002/chem.201801887
日期:2018.6.21
The Pd‐catalyzed Fukuyama reaction of thioesters with organozinc reagents is a mild, functional‐group‐tolerant method for acylation chemistry. Its Ni‐catalyzed variant might be a sustainable alternative to expensive catalytic Pd sources. We investigated the reaction of S‐ethyl thioesters with aryl zinc halides with hetero‐ and homotopic Ni precatalysts and several ligands. The results show that both
Mechanism of SmI<sub>2</sub>/Amine/H<sub>2</sub>O-Promoted Chemoselective Reductions of Carboxylic Acid Derivatives (Esters, Acids, and Amides) to Alcohols
作者:Michal Szostak、Malcolm Spain、Andrew J. Eberhart、David J. Procter
DOI:10.1021/jo5018525
日期:2014.12.19
Samarium(II) iodide–water–amine reagents have emerged as some of the most powerful reagents (E° = −2.8 V) for the reduction of unactivated carboxylic acid derivatives to primaryalcohols under single electron transfer conditions, a transformation that had been considered to lie outside the scope of the classic SmI2 reductant for more than 30 years. In this article, we present a detailed mechanistic