An efficient and mild method for the synthesis of 4,5-disubstituted oxazoles has been developed. A series of 4,5-disubstituted oxazoles were prepared via [3 + 2] cycloaddition reaction of various isocyanides and acid chlorides in the presence of base. This method serves as an efficient preparation of 5-formyloxazole which might prove to be a synthetically useful intermediate.
Nano-copper catalysed highly regioselective synthesis of 2,4-disubstituted pyrroles from terminal alkynes and isocyanides
作者:Dipak Kumar Tiwari、Jaya Pogula、B. Sridhar、Dharmendra Kumar Tiwari、Pravin R. Likhar
DOI:10.1039/c5cc04166j
日期:——
Nano-copper(0) stabilized on alumina prepared from Cu–Al hydrotalcite has been reported for completely regioselective synthesis of 2,4-disubstituted pyrroles from unactivated terminal aromatic/aliphatic alkynes and isocyanides.
The alkylation of imidazole-4(5)-carboxylic acid anilide and methyl ester with bromoacetic acid and its methyl ester in neutral and alkaline media yields, along with monoalkylation products, 1,3-bis(2-methoxycarbonylmethyl)-4-R-imidazolium bromide. The monoalkylation of methyl imidazole-4(5)-carboxylate yields a I :1 mixture of the 1,4- and 1,5-isomers, and the monoalkylation of imidazole-4(5)-carboxylic anilide selectively provides the 1,4-isomer.
Versatile Direct Synthesis of Oligosubstituted Pyrroles by Cycloaddition of α-Metalated Isocyanides to Acetylenes