The metal-free [2 + 2 + 1] annulation of alkynes, nitriles, and O-atoms for the regioselective assembly of 2,4-disubstituted and 2,4,5-trisubstituted oxazole compounds has been achieved by the use of PhIO with TfOH or Tf2NH. The present reaction could be applied to a facile synthesis of an anti-inflammatory drug.
Iodine(III)-Catalyzed Formal [2 + 2 + 1] Cycloaddition Reaction for Metal-Free Construction of Oxazoles
作者:Takuma Yagyu、Yusuke Takemoto、Akira Yoshimura、Viktor V. Zhdankin、Akio Saito
DOI:10.1021/acs.orglett.7b00742
日期:2017.5.19
The iodine(III) catalyst, in situ generated from iodoarene as a precatalyst with m-CPBA and Tf2NH, promoted the metal-free [2 + 2 + 1] cycloaddition-type reactions of alkynes, nitriles, and oxygen atoms for the regioselective formations of 2,4-disubstituted and 2,4,5-trisubstituted oxazole. A first example of iodine catalysis for multicomponent reactions is represented.
Development of β,β-Dibrominated Secondary Enamides and Their Application to the Synthesis of 5-Br Oxazoles
作者:Jun Ma、Qijie Zou、Chunhua Wang、Guangwei Yin、Fangyi Li
DOI:10.1021/acs.joc.2c01927
日期:2022.11.18
Herein, we report a base promoted dibromination of enamides using CBr4 as a bromine source to provide expedient access to β,β-dibrominated secondary enamides. Preliminary synthetic application study shows that these novel products can be readily transformed to 5-Br oxazoles via Cu(I) catalyzed intramolecular cyclization in good yields.