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.
Stereoselective addition reactions of alkynes with benzenetellurinyl trifluoromethanesulfonate in acetonitrile: organotellurium-mediated one-pot synthesis of oxazoles from internal alkynes
Benzenetellurinyl trifluoromethanesulfonate in conjunction with acetonitrile underwent an E-stereoselective amidotellurinylation reaction with alkynes, but the addition products from terminal alkynes tended to isomerize thermally to (Z)-β-acetamidovinyl phenyl telluroxide, whereas those from internal alkynes were transformed into oxazoles via a spontaneous intramolecular cyclization.