Journal of the Serbian Chemical Society 2004 Volume 69, Issue 10, Pages: 737-747
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Stereoselective free radical phenylsulfenylation of a nonactivated δ-carbon atom
Petrović Goran, Saičić Radomir N., Došen-Mićović Ljiljana I., Čeković Živorad
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.
Keywords: radical reactions, stereoselective reactions, C-H activation, absolute configurations, ab initio calculations, menthyl benzenesulfenate, 9-phenylthiomenthol
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