Borylative Heterocyclization without Air-Free Techniques
作者:Chao Gao、Shuichi Nakao、Suzanne A. Blum
DOI:10.1021/acs.joc.0c01096
日期:2020.8.21
In contrast to previously reported borylative heterocyclization methods, a reaction here proceeds without air-free techniques to access synthetically useful borylated thiophenes, benzothiophenes, and isocoumarins. A comparison of stability/decomposition rates in air of several catecholboronic ester (Bcat) compounds derived from different heterocycle cores showed a strong dependence on the heterocycle
Catalyst-Free Formal Thioboration to Synthesize Borylated Benzothiophenes and Dihydrothiophenes
作者:Darius J. Faizi、Ashlee J. Davis、Fiach B. Meany、Suzanne A. Blum
DOI:10.1002/anie.201608090
日期:2016.11.7
isolated prior to downstream functionalization. This methodology has been extended to the synthesis of borylated dihydrothiophenes. Mechanistic experiments suggest that the operative mechanistic pathway is through boron‐induced activation of the alkyne followed by electrophilic cyclization, as opposed to S−B σ bond formation, providing a mechanistically distinct pathway to the thioboration of C−C π bonds.
A new method for the directsynthesis of 3-phosphinoylbenzothio(seleno)phenes has been achieved through an Ag-mediated radical addition–cyclization of 2-alkynylthio(seleno)anisoles with secondary phosphine oxides in good yields under mild conditions. In this single reaction, benzenethiophene or benzeneselenophene skeleton, C(sp2)–P and C(sp2)–S bonds can be constructed with the cleavage of the C(sp3)–S
B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>-Catalyzed cyclization of alkynes: direct synthesis of 3-silyl heterocyclic compounds
作者:Mengxing Li、Ting Wang、Zhenyu An、Rulong Yan
DOI:10.1039/d0cc04314a
日期:——
An efficient one-pot strategy for easy access to 3-silyl heterocyclic compounds was developed via a B(C6F5)3-catalyzed cycloaddition reaction of o-(1-alkynyl)(thio)anisoles or o-(1-alkynyl)-N-methylaniline.
Synthesis of 2-substituted benzo[<i>b</i>]thiophenes <i>via</i> gold(<scp>i</scp>)–NHC-catalyzed cyclization of 2-alkynyl thioanisoles
作者:Christopher C. Dillon、Bagieng Keophimphone、Melissa Sanchez、Parveen Kaur、Hubert Muchalski
DOI:10.1039/c8ob02196a
日期:——
developed for the construction of a benzo[b]thiophene core via cyclization reaction of alkynes. Although few catalytic reactions were disclosed, most methods rely on stoichiometric activation of alkynes. Here we report an efficient method for the synthesis of 2-substituted benzo[b]thiophenes from 2-alkynyl thioanisoles catalyzed by a gold(I)–IPr hydroxide that is applicable to a wide range of substrates
苯并[ b ]噻吩杂环是许多重要的小分子药物和候选药物以及有机半导体材料的重要组成部分。已经开发了许多通过炔烃的环化反应来构建苯并[ b ]噻吩核的方法。尽管公开的催化反应很少,但是大多数方法依赖于炔烃的化学计量活化。在这里我们报告了一种由金催化的由2-炔基硫代苯甲醚合成2-取代的苯并[ b ]噻吩的有效方法(I)– IPr氢氧化物,适用于具有多种电子和空间特性的多种底物。另外,我们通过实验证明了酸添加剂及其共轭碱对催化剂周转至关重要。