Geminal Metalloid Substituents Enable Stereoselective Geometric Isomerization of Highly Substituted Alkenes via Energy-Transfer Catalysis
- 1Institute of Chemistry
- 2Center for Nanoscience and Nanotechnology, Casali Center for Applied Chemistry, The Hebrew University of Jerusalem
- 3Department of Chemistry, Westmont College, 955 La Paz Road, Santa Barbara, USA, CA-93108
Abstract
Controlling alkene geometry with high stereochemical precision remains a fundamental challenge in synthetic chemistry, particularly for highly substituted systems. Here we report a stereoselective photoisomerization of gem-diborylalkenes in which visible light enables efficient E→Z interconversion of geminal metalloids-substituted carbon–carbon double bonds through a triplet energy-transfer (EnT) mechanism, overcoming the long-standing limitation of stereoselective photoisomerization of highly (tetra)substituted alkenes. A broad range of tri- and tetra-substituted alkenes are converted to the thermodynamically less stable Z-isomer with up to 99:1 selectivity. Mechanistic studies and density functional theory (DFT) calculations reveal that stereocontrol arises from both interplay between excited-state deconjugation due to steric bulkiness and substratephotocatalyst interactions. Sequential functionalizations of both geometrically defined diborylalkene isomers are also demonstrated, enabling the stereodivergent construction of complex stereodefined alkenes. Beyond facilitating stereoselective geometric isomerization of tri- and tetrasubstituted alkenes, this work establishes (gem)-dimetalloid alkenes as light-programmable scaffolds and introduces a general strategy for boron-mediated photochemical control of alkene stereochemistry with implications for molecular and materials design.
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BibTeX
@misc{eghbarieh2026geminal,
title = {{Geminal Metalloid Substituents Enable Stereoselective Geometric Isomerization of Highly Substituted Alkenes via Energy-Transfer Catalysis}},
author = {Nadim Eghbarieh and Nicole Hanania and Brandon E. Haines and Ahmad Masarwa},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15009548/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009548/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Geminal Metalloid Substituents Enable Stereoselective Geometric Isomerization of Highly Substituted Alkenes via Energy-Transfer Catalysis
AU - Nadim Eghbarieh
AU - Nicole Hanania
AU - Brandon E. Haines
AU - Ahmad Masarwa
PY - 2026
DA - 2026/09/28
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009548/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009548/v1
AB - Controlling alkene geometry with high stereochemical precision remains a fundamental challenge in synthetic chemistry, particularly for highly substituted systems. Here we report a stereoselective photoisomerization of gem-diborylalkenes in which visible light enables efficient E→Z interconversion of geminal metalloids-substituted carbon–carbon double bonds through a triplet energy-transfer (EnT) mechanism, overcoming the long-standing limitation of stereoselective photoisomerization of highly (tetra)substituted alkenes. A broad range of tri- and tetra-substituted alkenes are converted to the thermodynamically less stable Z-isomer with up to 99:1 selectivity. Mechanistic studies and density functional theory (DFT) calculations reveal that stereocontrol arises from both interplay between excited-state deconjugation due to steric bulkiness and substratephotocatalyst interactions. Sequential functionalizations of both geometrically defined diborylalkene isomers are also demonstrated, enabling the stereodivergent construction of complex stereodefined alkenes. Beyond facilitating stereoselective geometric isomerization of tri- and tetrasubstituted alkenes, this work establishes (gem)-dimetalloid alkenes as light-programmable scaffolds and introduces a general strategy for boron-mediated photochemical control of alkene stereochemistry with implications for molecular and materials design.
ER -