title: Conformational analysis of spiro-bis-dithiepins: a peculiar case of axial chirality.
abstract: Spiro-bis-dithiepins are synthesized via dehydrative ring expansion in alpha-hydroxyalkyl spiro-bis-dithianes. Atypical of spiranes possessing axial chirality, the two most stable conformers of substituted spiro-bis-dithiepin have virtually colinear double bonds; i.e., each enantiomer exists in a form of two energy degenerate syn and anti conformations. Because of the high polarizability of the vinyl sulfide moiety, spiro-bis-dithiepins bearing electron-withdrawing substituents offer access to two-state systems possessing large dipole moments, which can be modulated by conformational events. [structure: see text]
authors.affiliation: Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA.
authors.forename: Edmir O
authors.initials: EO
authors.lastname: Wade
authors.forename: Roman A
authors.initials: RA
authors.lastname: Valiulin
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Ruybal
authors.forename: Andrei G
authors.initials: AG
authors.lastname: Kutateladze