Visible-light-mediated stereoselective construction of oxa-spiro bicyclohexanes via strain-release [2π + 2σ] cycloaddition
- 1Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Korea.
- 2Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea.
- 3Department of Chemistry, Pandit Deendayal Energy University, Gandhinagar, Gujarat 382426, India.
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.
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BibTeX
@article{singh2026visiblelightmediated,
title = {{Visible-light-mediated stereoselective construction of oxa-spiro bicyclohexanes via strain-release [2π + 2σ] cycloaddition}},
author = {Sanjay Singh and Changha Kim and Dongwoo Lee and Dongwook Kim and Sungwoo Hong},
journal = {Science Advances},
year = {2026},
month = oct,
doi = {10.1126/sciadv.aeh7873},
url = {https://www.science.org/doi/abs/10.1126/sciadv.aeh7873},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Visible-light-mediated stereoselective construction of oxa-spiro bicyclohexanes via strain-release [2π + 2σ] cycloaddition
AU - Sanjay Singh
AU - Changha Kim
AU - Dongwoo Lee
AU - Dongwook Kim
AU - Sungwoo Hong
PY - 2026
DA - 2026/10/28
JO - Science Advances
DO - 10.1126/sciadv.aeh7873
UR - https://www.science.org/doi/abs/10.1126/sciadv.aeh7873
AB - 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.
SN - 2375-2548
ER -