Optically active cyclic diaryl(alkoxy)sulfonium salts with intramolecular S···O interaction: synthesis, absolute configuration and stereoselective hydrolysis

• Published in: Tetrahedron: asymmetry Vol. 11; no. 6; pp. 1303 - 1312
• Main Authors: Szabó, Dénes, Varga, Jenő, Csámpai, Antal, Kapovits, István
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 07.04.2000
• ISSN: 0957-4166; 1362-511X
• DOI: 10.1016/S0957-4166(00)00064-1

Optically active cyclic sulfonium salts {( S)-(−)-1-[2′-(methoxycarbonyl)phenyl]-3 H-2,1-benzoxathiol-1-ium tetrafluoroborate ( S)-(−)- 2, ( R)-(−)-1-[8′-(methoxycarbonyl)-1′-naphthyl]-3 H-2,1-benzoxathiol-1-ium tetrafluoroborate ( R)-(−)- 4 and ( R)-(−)-1-[2′-(methoxycarbonyl)phenyl]-3 H-2,1-naphtho[1,8- d, e]-oxathiin-1-ium tetrafluoroborate ( R)-(−)- 6} were prepared from optically active diaryl(acyloxy)(alkoxy)spiro-λ 4-sulfanes ( R)-(+)- 1, ( S)-(−)- 3 and ( S)-(+)- 5, respectively. The molecular structures determined by 1H and 13C NMR measurements can be described with spiro-λ 4-sulfane-like trigonal bipyramidal geometry about the central sulfur owing to the S···O(carbonyl) intramolecular interaction in the axial position. The stereochemistry of the hydrolysis reactions of sulfonium salts 2, 4, 6 and spiro-λ 4-sulfanes 1, 3, 5 depending on pH is discussed in detail.