Regioselective Chromatic Orthogonality with Light-Activated Metathesis Catalysts

The ability to selectively guide consecutive chemical processes towards a preferred pathway by using light of different frequencies is an appealing concept. Herein we describe the coupling of two photochemical reactions, one the photoisomerization and consequent activation of a sulfur‐chelated laten...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2015-10, Vol.54 (42), p.12384-12388
Main Authors: Levin, Efrat, Mavila, Sudheendran, Eivgi, Or, Tzur, Eyal, Lemcoff, N. Gabriel
Format: Article
Language:English
Subjects:
Activation
Alkenes - chemistry
Catalysis
Catalysts
chromatic orthogonality
cyclization
Cycloparaffins - chemical synthesis
Cycloparaffins - chemistry
Decomposition reactions
heterocycles
Light
Metathesis
Molecular Structure
olefin metathesis
Orthogonality
Pathways
Photochemical Processes
photochemistry
Stereoisomerism
Synthesis
Wavelengths
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Summary:The ability to selectively guide consecutive chemical processes towards a preferred pathway by using light of different frequencies is an appealing concept. Herein we describe the coupling of two photochemical reactions, one the photoisomerization and consequent activation of a sulfur‐chelated latent olefin‐metathesis catalyst at 350 nm, and the other the photocleavage of a silyl protecting group at 254 nm. Depending on the steric stress exerted by a photoremovable neighboring chemical substituent, we demonstrate the selective formation of either five‐ or six‐membered‐ring frameworks by light‐triggered ring‐closing metathesis. The orthogonality of these light‐induced reactions allows the initiation of these processes independently and in interchangeable order, according to the wavelength of light used to promote them. A guiding light: By the combination of a light‐activated sulfur‐chelated olefin‐metathesis catalyst with a photocleavable bulky silyl protecting group, two orthogonal pathways enabled the selective synthesis of five‐ or six‐membered heterocycles according to the order in which the starting material was irradiated with light of different wavelengths. Thus, protecting‐group removal and metathesis gave either a dihydropyran or a dihydrofuran.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201500740