divergent approach to indoles and oxazoles from enamides has been developed. The picolinamide-derived enamides undergo the intramolecular aromatic C–H amination in the presence of a Cu(OPiv)2 catalyst and an MnO2 oxidant to form the corresponding indoles in good yields. On the other hand, simpler aryl- or alkyl-substituted enamides are converted to the 2,4,5-trisubstituted oxazole frameworks via vinylic C–H
A novel [3 + 2] cycloaddition/oxidative aromatization sequence via visible light-induced photoredox catalysis is disclosed. It provides a general synthetic route to 2,4,5-trisubstituted oxazoles from easily accessible 2H-azirines and aldehydes under mild reaction conditions. The potential of this strategy was further demonstrated by the rapid synthesis of a cyclooxygenase-2 inhibitor as well as the
An efficient synthesis of trisubstituted oxazoles via chemoselective O-acylations and intramolecular Wittig reactions
作者:Yi-Ling Tsai、Yu-Shiou Fan、Chia-Jui Lee、Chan-Hui Huang、Utpal Das、Wenwei Lin
DOI:10.1039/c3cc45883k
日期:——
Preparation of new types of trisubstituted oxazoles is realized via chemoselective O-acylations and intramolecular Wittig reactions with ester functionalities using in situ formed phosphorus ylides as key intermediates. A plausible reaction mechanism for this undiscovered chemistry is also proposed based on the existence of expected and rearranged isomeric oxazoles.
C–H heteroarylation of aromatics <i>via</i> catalyst free S<sub>N</sub>2′ coupling cycloaromatization
作者:Qixing Lu、Tao Wang、Qian Wu、Lijing Cheng、Han Luo、Lei Liu、Guobiao Chu、Lufeng Wang、Baosheng Li
DOI:10.1039/d2gc00467d
日期:——
construction of a carbon–carbon bond is the most fundamental aspect of synthetic chemistry. In this study, we developed a catalyst-free SN2′ reaction of β-OTf-substituted enamides with aromatics to obtain aryl-substituted aza-1,4-dicarbonyl compounds that can be in situ transformed into aryl-imidazole, aryl-thiazole, and aryl-oxazole in one-pot operation, thus achieving C–Hheteroarylation of aromatics. This simple
碳-碳键的构建是合成化学最基本的方面。在这项研究中,我们开发了 β-OTf 取代的烯酰胺与芳烃的无催化剂 S N 2' 反应,以获得芳基取代的 aza-1,4-二羰基化合物,该化合物可以原位转化为芳基咪唑、芳基-噻唑和芳基恶唑在一锅操作中,从而实现芳烃的 C-H 杂芳基化。这种简单、高效、清洁和可扩展的策略提供了难以实现的联芳基产品,与具有不同复杂性的各种芳烃兼容。该方法可用于各种商业药物或功能材料的后期改性,并为构建联芳基化合物提供了一种正交方法。
SHRIDHAR, D. R.;RAM, B.;SARMA, C. R.;SAXENA, N. K.;THAPER, G. S.;KRISHNAM+, INDIAN J. CHEM., 1982, 21, N 9, 860-864
作者:SHRIDHAR, D. R.、RAM, B.、SARMA, C. R.、SAXENA, N. K.、THAPER, G. S.、KRISHNAM+