Catalytic, Enantioselective, Intramolecular Sulfenofunctionalization of Alkenes with Phenols
| Autor: | Scott E. Denmark, David J. P. Kornfilt |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
chemistry.chemical_classification
Steric effects Magnetic Resonance Spectroscopy 010405 organic chemistry Alkene Organic Chemistry Enantioselective synthesis Stereoisomerism Alkenes 010402 general chemistry Sulfamerazine 01 natural sciences Medicinal chemistry Catalysis Article 0104 chemical sciences Phenols chemistry Nucleophile Cyclization Electrophile Organic chemistry Moiety Reactivity (chemistry) Lewis acids and bases |
| Zdroj: | The Journal of Organic Chemistry |
| ISSN: | 1520-6904 0022-3263 |
| DOI: | 10.1021/acs.joc.7b00295 |
| Popis: | The catalytic, enantioselective, cyclization of phenols with electrophilic sulfenophthalimides onto isolated or conjugated alkenes affords 2,3-disubstituted benzopyrans and benzoxepins. The reaction is catalyzed by a BINAM-based phosphoramide Lewis base catalyst which assists in the highly enantioselective formation of a thiiranium ion intermediate. The influence of nucleophile electron density, alkene substitution pattern, tether length and Lewis base functional groups on the rate, enantio- and site-selectivity for the cyclization is investigated. The reaction is not affected by the presence of substituents on the phenol ring. In contrast, substitutions around the alkene strongly affect the reaction outcome. Sequential lengthening of the tether results in decreased reactivity, which necessitated increased temperatures for reaction to occur. Sterically bulky aryl groups on the sulfenyl moiety prevented erosion of enantiomeric composition at these elevated temperatures. Alcohols and carboxylic acids preferentially captured thiiranium ions in competition with phenolic hydroxyl groups. An improved method for the selective C(2) allylation of phenols is also described. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|