Denitrogenative Triazole Ring Cleavage in Synthesis of 2‐Functionalized (Cyclo)alkyl‐4.5‐Unsubstituted Oxazoles

A series of 2-(cyclo)alkyl-substituted oxazoles is synthesized via a denitrogenative triazole ring-cleavage strategy. The solvent-free conditions allow the introduction of primary and secondary amines, as well as carboxylic and alkoxycarboxylic groups on the (cyclo)alkyl side chain. The approach is also applicable to optically active substrates, enabling the synthesis of oxazole-containing α-amino acids from readily available D- and L-aspartic acid.

Denitrogenative triazole ring cleavage is applied for the preparation of a broad set of 2-(cyclo)alkylo-xazole derivatives. The proposed procedures involve carrying out the reaction of 1,2,3-triazole with various functionally substituted acid chlorides in sulfolane or under neat conditions. Despite the exothermic nature of the reaction, it affords the target products in high yield. Various functional groups are tolerated in the (cyclo)alkyl chain such as protected primary and secondary amine and esters. The developed procedure is applied for the preparation of optically active amino acids featuring oxazole moiety.

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