An efficient synthesis of 2,5-disubstitutedoxazolesvia Co(III) catalysis is described herein. The synthesis is achieved under mild conditions through [3+2] cycloaddition of N-pivaloyloxyamides and alkynes. The reaction operates through an internal oxidation pathway and features a very broad substrate scope. The one-step synthesis of natural products such as texamine and balsoxin has been demonstrated
Formation of Acyl-Substituted Nitrile Ylides by Rh<sub>2</sub>(OAc)<sub>4</sub>-Catalyzed Decomposition of<i>α</i>-Diazocarbonyl Compounds in Nitriles
作者:Kazuaki Fukushima、Toshikazu Ibata
DOI:10.1246/bcsj.68.3469
日期:1995.12
The Rh2(OAc)4-catalyzed reactions of α-diazocarbonyl compounds in nitrile in the presence of dimethyl acetylenedicarboxylate (DMAD) gave oxazole and pyrrole derivatives. The formation of the oxazole derivatives is explained in terms of the 1,5-cyclization of an acyl-substituted nitrileylide intermediate, and the formation of the pyrrole derivatives is explained by the 1,3-dipolar cycloaddition of
A practicalone‐pot protocol for the synthesis of 2,5‐disubstitutedoxazoles from 1‐aryl‐2‐nitroethanones was reported. In the presence of iron/AcOH in acetonitrile, the reaction of 1‐aryl‐2‐nitroethanones with trimethyl orthoacetate or trimethyl orthobenzoate delivered the corresponding 2,5‐disubstitutedoxazoles in moderate to good yields.
Synthesis of Oxazoles through Copper-Mediated Aerobic Oxidative Dehydrogenative Annulation and Oxygenation of Aldehydes and Amines
作者:Zejun Xu、Chun Zhang、Ning Jiao
DOI:10.1002/anie.201206382
日期:2012.11.5
A fragment‐assembling strategy is used to form oxazoles from aryl acetaldehydes, amines, and molecular oxygen under mild conditions (see scheme). The transformation is highly efficient with the removal of six hydrogen atoms, including the cleavage of four C(sp3)H bonds.