Direct excitation of carbonyl cyclopropanes: From divergent photo-isomerization and annulation to unified reductive C-C cleavage

22 May 2024, Version 2
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

We report herein our studies on the direct photoactivation of carbonyl cyclopropanes to give biradical intermediates, leading to selective cleavage of the more substituted carbon-carbon bond. Depending on the substrate structure, extended alkenes were isolated or directly reacted in a photo-Nazarov process to give bicyclic products. Based on these results, a unified reductive ring-opening reaction was developed by using diphenyl disulfide as a HAT reagent. By performing a sequential cyclopropanation/selective ring opening reaction, we achieved a CH2 insertion into the alpha,beta- bond of both acyclic and cyclic unsaturated carbonyl compounds. Our protocol therefore provides a further tool for framework-editing of carbocycles, complementing the recent progress in "skeletal editing" strategies.

Keywords

photochemistry
strained rings
cyclopropanes
biradicals
photoisomerization
Norrish type II
Hydrogen Atom Transfer
Nazarov
C-C bond activation

Supplementary materials

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Description
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Supplementary information
Description
General methods, experimental procedures, characterization data, computational details and copy of NMR spectra for new compounds
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cartesian coordinates
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Cartesian coordinates of optimized structures for computation
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