Oxetane Cleavage Pathways in the Excited State: Photochemical Kinetic Resolution as an Approach to Enantiopure Oxetanes.

ABSTRACT: Chiral spirocyclic oxetanes [2-oxo-spiro(3H-indole-3,2'-oxetanes)] were subjected to irradiation in the presence of a chiral thioxanthone catalyst (5 mol %) at λ = 398 nm. An efficient kinetic resolution was observed, which led to an enrichment of one oxetane enantiomer as the major enantiomer (15 examples, 37-50% yield, 93-99% ee). The minor enantiomer underwent decomposition, and the decomposition products were carefully analyzed. They arise from a photocycloreversion (retro-Paternò-Büchi reaction) into a carbonyl component and an olefin. The cycloreversion offers two cleavage pathways depending on whether a C-O bond scission or a C-C bond scission occurs at the spirocyclic carbon atom. The course of this reaction was elucidated by a suite of mechanistic, spectroscopic, and

SUBMITTER: Pflaum N 

PROVIDER: S-EPMC12022993 | biostudies-literature | 2025 Apr

REPOSITORIES: biostudies-literature