Mild olefin formation via bio-inspired vitamin B12 photocatalysis

Dehydrohalogenation, or elimination of hydrogen-halide equivalents, remains one of the simplest methods for the installation of the biologically-important olefin functionality. However, this transformation often requires harsh, strongly-basic conditions, rare noble metals, or both, limiting its applicability in the synthesis of complex molecules. Nature has pursued a complementary approach in the novel vitamin B-12-dependent photoreceptor CarH, where photolysis of a cobalt-carbon bond leads to selective olefin formation under mild, physiologically-relevant conditions. Herein we report a light-driven B-12-based catalytic system that leverages this reactivity to convert alkyl electrophiles to olefins under incredibly mild conditions using only earth abundant elements. Further, this process exhibits a high level of regioselectivity, producing terminal olefins in moderate to excellent yield and exceptional selectivity. Finally, we are able to access a hitherto-unknown transformation, remote elimination, using two cobalt catalysts in tandem to produce subterminal olefins with excellent regioselectivity. Together, we show vitamin B-12 to be a powerful platform for developing mild olefin-forming reactions.

Automated summary

This study presents a light-driven B-12-based catalytic system that can convert alkyl electrophiles to olefins under incredibly mild conditions with high regioselectivity and exceptional selectivity. Additionally, the use of two cobalt catalysts in tandem enables the production of subterminal olefins with excellent regioselectivity, showcasing vitamin B-12 as a powerful platform for developing mild olefin-forming reactions.