Pa. Kikilo et al., Stereochemistry of seven-membered heterocycles: XLI. Stereoselective synthesis of 3-R-1,5-dihydro-2,4-benzothiepine 2-oxides, RUSS J G CH, 71(6), 2001, pp. 960-964
The oxidation of 3-R-1,5-dihydro-2,4-benzothiepines with m-chloroperbenzoic
acid occurs in a highly diastereoselective fashion. The resulting trans-su
lfoxides at -60 degreesC in CDCl3 exist as an equilibrium mixture of the ch
air and boat forms with the substituents in the equatorial position. The fr
action of the boat conformation increases in the series R = Ph, Me, t-Bu.