Stereoselective free radical phenylsulfenylation of a nonactivated δ-carbon atom

• Main Authors: Petrović Goran, Saičić Radomir N., Došen-Mićović Ljiljana I., Čeković Živorad
• Format: Article
• Language: English
• Published: Serbian Chemical Society 2004-01-01
• Series: Journal of the Serbian Chemical Society
• Subjects: radical reactions; stereoselective reactions; c-h activation; absolute configurations; ab initio calculations; menthyl benzenesulfenate; 9-phenylthiomenthol
• Online Access: http://www.doiserbia.nb.rs/img/doi/0352-5139/2004/0352-51390410737P.pdf
• ISSN: 0352-5139; 1820-7421

A stereoselective free radical introduction of a phenylthio group onto a nonactivated methyl group in the δ-position, adjacent to a prochiral carbon atom, was achieved by photolysis of (-)-menthyl benzenesulfenate in the presence of hexabutylditin and (1R, 3R, 4S, 8S)-9-phenylthiomenthol (4) was obtained with 91%optical purity. High stereoselectivity of the reaction was calculated (ab initio MP2/6-31G**) to be the consequence of the difference in the transition state eneregies (ΔΔG# = 5.08 kJ/mol) favouring 4 relative to (1R,3R,4S,8R)-9-phenylthiomenthol (5). The absolute configuration of a the new chiral carbon atom was confirmed by its correlation with the corresponding menthane-3,9-diol of known stereochemistry.