Cross-dehydrogenative coupling of coumarins with Csp3–H bonds using an iron–organic framework as a productive heterogeneous catalyst?

RSC Advances Pub Date: 2018-03-19 DOI: 10.1039/C8RA00872H

Abstract

The iron–organic framework VNU-20 was utilized as an active heterogeneous catalyst for the cross-dehydrogenative coupling of coumarins with Csp3–H bonds in alkylbenzenes, cyclohexanes, ethers, and formamides. The combination of DTBP as the oxidant and DABCO as the additive led to high yields of coumarin derivatives. The VNU-20 was more active towards this reaction than numerous other homogeneous and heterogeneous catalysts. Heterogeneous catalysis was confirmed for the cross-dehydrogenative coupling transformation utilizing the VNU-20 catalyst, and the contribution of active iron species in the liquid phase was insignificant. The iron-based framework was reutilized many times for the functionalization of coumarins without a remarkable decline in catalytic efficiency. To the best of our knowledge, these reactions of coumarins have not previously been conducted using heterogeneous catalysts.

Graphical abstract: Cross-dehydrogenative coupling of coumarins with Csp3–H bonds using an iron–organic framework as a productive heterogeneous catalyst
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