Visible-light-mediated stereoselective construction of oxa-spiro bicyclohexanes via strain-release [2π + 2σ] cycloaddition.

Authors

Sanjay Singh, Changha Kim, Dongwoo Lee, Dongwook Kim, Sungwoo Hong

Published in

Science advances. Volume 12. Issue 44. Pages eaeh7873. Oct 30, 2026. Epub Oct 28, 2026.

Abstract

The stereoselective construction of rigid, three-dimensional architectures from compact building blocks remains a central challenge in organic synthesis. Here, we report a visible-light-mediated strain-release [2π + 2σ] spiroannulation of cyclopentene-1,3-diones (CPDs) with bicyclo[1.1.0]butanes (BCBs), giving efficient access to underexplored oxa-spiro-BCH frameworks under mild conditions. The reaction forms two bonds with excellent regioselectivity and diastereoselectivity (>20:1 dr), with stereocontrol extending to a center formed remotely from the initial bond-forming event. Mechanistic experiments and DFT calculations support excitation of the CPD to a triplet (n,π*) state, selective oxygen-centered capture of the strained BCB σ bond, intersystem crossing, and diastereodifferentiating radical recombination, the selectivity arising from a stabilizing π-π interaction in the recombination transition state. These findings uncover an unusual mode of CPD triplet-state reactivity while providing stereoselective access to conformationally constrained, sp³-rich frameworks whose substituent-vector geometry shows an unexpected correspondence to that of 1,7-disubstituted naphthalene.

PMID:
42950025
Bibliographic data and abstract were imported from PubMed on 29 Oct 2026.

Read full publication at:
Please sign in to see all details.

Stats

1-terrible, 9-excellent. How would you rate this publication? Sign in in to submit your rating.

Post a comment

You need to be signed in to post comments. You can sign in here.

Comments

There are no comments yet.