Asymmetric Catalytic Cycloetherification Mediated by Bifunctional Organocatalysts
摘要:
Oxacyclic structures such as tetrahydrofuran (THF) rings are commonly found in many bioactive compounds, and this has led to several efforts toward their stereoselective syntheses. However, the process of catalytic asymmetric cycloetherification for their straightforward synthesis has remained a challenge. In this study, we demonstrate a novel asymmetric synthesis method for THF via the catalytic cycloetherification of epsilon-hydroxy-alpha,beta-unsaturated ketones mediated by cinchona-alkaloid-thiourea-based bifunctional organocatalysts. This catalytic process represents a highly practical cycloetherification method that provides excellent enantioselectivities, even with low catalyst loadings at ambient temperature.
Copper-catalyzed dehydrogenative cross-coupling reaction between unactivated ethers and simple ketones mediated by pyrrolidine
作者:Xing-Fen Huang、Zhi-Qiang Zhu、Zhi-Zhen Huang
DOI:10.1016/j.tet.2013.07.085
日期:2013.10
A copper-catalyzed dehydrogenative cross-coupling reaction between unactivated ethers and simpleketones mediated by pyrrolidine has been developed. Under the catalysis of CuBr2 and in the presence of pyrrolidine, either tetrahydrofuran 2a or tetrahydropyran 2b can react smoothly with a series of methyl aryl ketones 1a–m to give desired coupling products 3aa–mb using TBHP as an oxidant. The advantages
Visible-light-promoted oxidative coupling of styrene with cyclic ethers
作者:Golam Kibriya、Debashis Ghosh、Alakananda Hajra
DOI:10.1007/s11426-019-9609-9
日期:2020.1
A new visible-light-promoted oxidative coupling of vinylarenes with cyclic ethers has been developed using rose bengal as photocatalyst and tert-butyl hydrogenperoxide (TBHP) as oxidant under ambient air at room temperature. A library of α-oxyalkylated ketones with broad functionalities has been synthesized in moderate to good yields. A radical mechanism is suggested for the present protocol
Organocatalytic Enantioselective Cycloetherifications Using a Cooperative Cation-Binding Catalyst
作者:Amol P. Jadhav、Jeong-A Oh、In-Soo Hwang、Hailong Yan、Choong Eui Song
DOI:10.1021/acs.orglett.8b02240
日期:2018.9.7
A highly enantioselective cycloetherification strategy for the straightforward synthesis of enantioenriched tetrahydrofurans, tetrahydropyrans, and oxepanes using Song’s cation-binding oligoEG catalyst and KF as the base is demonstrated. A wide range of ε-, ζ-, and η-hydroxy-α,β-unsaturated ketones were cyclized to the corresponding five-, six-, and seven-membered chiral oxacycles with high enantiopurity
Visible-light induced eosin Y catalysed C(sp2)-H alkylation of carbonyl substrates via direct HAT
作者:Satya Prakash Singh、Vishal Srivastava、Pravin K. Singh、Praveen P. Singh
DOI:10.1016/j.tet.2023.133245
日期:2023.2
(HAT) catalyst for C–Hactivation. A study that utilized the alkylation of C–H bonds with electron-deficientalkenes as a paradigm provided a very wide substrate scope that made it simple to access a number of significant synthons. This green and sustainable eosin Y-based photocatalytic hydrogen atom transfer method promises to diversify the functionalization of a variety of native C–H bonds.
Visible-Light-Driven Denitrogenative C–C Bond Formation and Oxidative Difunctionalization of Vinyl Azides
作者:Adinath Majee、Santosh Sing Sardar、Aramita De、Satyajit Pal、Subhankar Sarkar、Sougata Santra、Grigory V. Zyryanov
DOI:10.1055/a-2131-3208
日期:2024.2
A newer synthetic protocol has been developed to synthesize α-oxyalkyl ketonesfromvinylazides under transition-metal-free reaction conditions. The reaction proceeds in the presence of organic photoredox catalyst rose bengal, an oxidant tert-butyl hydroperoxide (TBHP), and ethers. A broad range of substituted vinylazides were found to react smoothly upon visible-light irradiation, which readily