Elemental Sulfur-Promoted Oxidative Rearranging Coupling between o-Aminophenols and Ketones: A Synthesis of 2-Alkyl benzoxazoles under Mild Conditions
作者:Thanh Binh Nguyen、Pascal Retailleau
DOI:10.1021/acs.orglett.7b01775
日期:2017.7.21
In the presence of N-methylpiperidine, elemental sulfur was found to act as excellent oxidant in promoting oxidative rearranging coupling between o-aminophenols and ketones. A wide range of 2-alkylbenzoxazoles was obtained under mild conditions.
An elegant and catalytic procedure for the one-step cyanomethylenation of C(sp3)–H bonds adjacent to benzazoles and ketones is described herein using DMF as a C-1 unit and TMSCN as the cyanide source. The copper-mediated reaction between DMF and TMSCN gives a cyanomethylene radical intermediate that reacts with 2-alkylbenzazoles or alkylketones to furnish desired cyanomethylenated compounds under palladium
Synthesis of 2-benzyl benzoxazoles and benzothiazoles <i>via</i> elemental sulfur promoted cyclization of styrenes with 2-nitrophenols and <i>N</i>,<i>N</i>-dialkyl-3-nitroanilines
作者:Truong K. Chau、Nguyen T. Ho、Tuan H. Ho、Anh T. Nguyen、Khoa D. Nguyen、Nam T. S. Phan、Ha V. Le、Tung T. Nguyen
DOI:10.1039/d3ob01775c
日期:——
Annulation of 2-nitrophenols and N,N-dialkyl-3-nitroanilines with styrenes in the presence of elemental sulfur and the base DABCO successfully yielded 2-benzyl benzoxazoles and 2-benzyl benzothiazoles, respectively.
N-heterocyclic carbene-Pd(II)-1-methylimidazole complex catalyzed C–H bond benzylation of (benzo)oxazoles with benzyl chlorides
作者:Ya-Yun Ji、Yu Zhang、Yuan-Yuan Hu、Li-Xiong Shao
DOI:10.1016/j.tet.2015.07.030
日期:2015.9
The first example of phosphine-free, NHC-Pd(II) complex catalyzed direct C-H bond benzylation of (benzo)oxazoles with benzyl chlorides was reported in this paper. Under the suitable conditions, all reactions worked well enough to give the desired C2-benzylated products in good to almost quantitative yields, providing a facile and straight pathway for the C-H bond benzylation of (benzo)oxazoles within short time. (C) 2015 Elsevier Ltd. All rights reserved.