The blueprints of light-harvesting biomolecules found in nature have given chemists the ability to use transition metal complexes and organic dyes to transform photons into chemical energy.¹ Recently, a user-friendly and metal-free UVA light-mediated borocyclopropanation of styrenes using continuous flow technology was reported by our group.²The cyclopropane moiety is widely prevalent in biologically active compounds due to its unique three-dimensional architecture with spatially well-defined substituents and the development of methods for their introduction into complex molecules is therefore of great interest. Functionalized cyclopropanes represent a convenient building block to target this moiety and boronic acid derivatives are a nice handle to tackle this goal. Moreover, while the silyl group can be a very polyvalent functionality, the carbon-silicium bond can be used as a bioisotere of the carbon-carbon double bond. Although carbon-carbon double bonds are prevalent in bioactive compounds, pharmacodynamic properties were revealed to be improved when a silylated functionality was introduced instead. In this work, metal-free, visible light-mediated and user-friendly conditions were applied and optimized in order to produce a broad range of highly valuable silylcyclopropylboronate esters. This method will allow orthogonal functionalization of borosilacyclopropaness in an useful way to add complexity to drug-like molecules.

1. Ciamician, G. Science, 1912, 36, 385.
2. Sayes, M.; Benoit, G.; Charette, A. B. Angew. Chem., Int. Ed., 2018, 57, 13514.
3. Taylor, R. D.; MacCoss, M. M.; Lawson, A. D. G. J. Med. Chem. 2014, 57, 5845.

Léa Thai-Savard

University of Montreal

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