Photoinduced site-selective alkenylation of alkanes and aldehydes with aryl alkenes

Hui Cao,Jeric Mun Chung Kwan,Koi Lin Wong,Yulong Kuang,Boon Beng Tan,Jie Wu,Xiangcheng Shi,Xiaogang Liu

doi:10.1038/s41467-020-15878-6

Hui Cao, Jeric Mun Chung Kwan + Show 6 more

Open Access

https://doi.org/10.1038/s41467-020-15878-6

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Abstract

The dehydrogenative alkenylation of C-H bonds with alkenes represents an atom- and step-economical approach for olefin synthesis and molecular editing. Site-selective alkenylation of alkanes and aldehydes with the C-H substrate as the limiting reagent holds significant synthetic value. We herein report a photocatalytic method for the direct alkenylation of alkanes and aldehydes with aryl alkenes in the absence of any external oxidant. A diverse range of commodity feedstocks and pharmaceutical compounds are smoothly alkenylated in useful yields with the C-H partner as the limiting reagent. The late-stage alkenylation of complex molecules occurs with high levels of site selectivity for sterically accessible and electron-rich C-H bonds. This strategy relies on the synergistic combination of direct hydrogen atom transfer photocatalysis with cobaloxime-mediated hydrogen-evolution cross-coupling, which promises to inspire additional perspectives for selective C-H functionalizations in a green manner.

Highlights

The dehydrogenative alkenylation of C-H bonds with alkenes represents an atom- and stepeconomical approach for olefin synthesis and molecular editing
We were inspired by direct hydrogen atom transfer (HAT) photocatalysts that could achieve the straightforward activation of C–H bonds[33]
We proposed that the combination of decatungstate anion and a cobaloxime catalyst could enable the direct activation and alkenylation of alkanes and aldehydes using alkenes as the feedstocks

Summary

Introduction

The dehydrogenative alkenylation of C-H bonds with alkenes represents an atom- and stepeconomical approach for olefin synthesis and molecular editing. In pursuing methods for olefin construction[25,26,27] and photomediated C–H bond functionalization[28,29,30,31], we aspired to develop an auxiliary-free and oxidant-free strategy for Csp3–H and Csp2(O)–H alkenylation with the C–H substrate as the limiting reagent (Fig. 1c). This would allow the late-stage functionalization of advanced synthetic intermediates and pharmaceutical relevant molecules without de novo synthesis[32]. Of particular interest was the a Auxiliary-assisted alkenylation: DG

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