Competing Intra- vs Intermolecular Nitrene Transfer in the [Au]-Catalysed Reaction of 2-Alkynylphenylazides

The possibility of interrupting the gold-catalysed intramolecular cyclization of 2-alkynylphenylazide derivatives, employing known nitrene transfer reagents such as anthranil and its isomer 1,2-benzisoxazole, has been attempted in search of developing simple tools for product diversification. With 1,2-benzisoxazoles, the intermolecular nitrene transfer leading to quinazoline is competitive with intramolecular azidoalkyne cyclization resulting in spiro indol-3-ylidene derivatives. However, in case of the reaction in the presence of anthranil, both intra- and intermolecular nitrene transfer processes result in the same product indol-3-ylidene.

Automated summary

In this study, the possibility of interrupting the gold-catalysed intramolecular cyclization was explored in order to develop simple tools for product diversification. It was found that using 1,2-benzisoxazoles, intermolecular nitrene transfer competed with intramolecular azidoalkyne cyclization resulting in spiro indol-3-ylidene derivatives. However, when anthranil was present, both intra- and intermolecular nitrene transfer processes led to the same product indol-3-ylidene.