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.
The direct CH benzylation of azoles with benzyl chlorides proceeds efficiently, via sequential cleavage of one sp2 CH bond and two sp3 CHbonds in the presence of a palladium catalyst, to generate a wide range of tribenzylated azoles with a quaternary carboncenter efficiently. The same catalyst could also promote the mono‐ and di‐benzylation reactions through fine turning of the base and reaction
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.