Selective monosulfoxidation of tetrathiafulvalenes into chiral TTF-sulfoxides.
Four inner tetrathiafulvalene-sulfoxides have been synthesized upon reaction of tetrathiafulvalene (TTF), tetramethyl-tetrathiafulvalene (TMTTF), tetrakis (thiomethyl)-tetrathiafulvalene (TMT-TTF), and bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) with enantiopure (+) or (-)-(8,8-dichlorocamphorylsulfonyl)-oxaziridine as oxidizing agent. Chiral HPLC studies indicate very weak enantioselectivities for TTF-SO 3 and TMTTF-SO 4, formation of racemic mixture in the case of TMT-TTF-SO 5, and a rather good selectivity, up to 44% ee, in the case of BEDT-TTF-SO 1. The solid state structures of TMTTF-SO 4 and TMT-TTF-SO 5 have been determined by single crystal X-ray diffraction. Both compounds crystallize as racemates in the centrosymmetric triclinic space group P-1. Theoretical calculations at DFT/B3LYP/6-31+G* level afford optimized geometries in good accordance with the experimental structures and emphasize the participation of the chiral sulfoxide group in HOMO and LUMO. Time-dependent DFT calculations corroborated with electronic circular dichroism spectra allow the assignment of the absolute configuration (R) for the major enantiomer of 1 when the (+)-sulfonyl-oxaziridine is used as oxygen transfer reagent. Preliminary semipreparative HPLC separation provided enantioenriched fractions up to 63% ee.
Chas
Marcos
M
CNRS, Laboratoire de Chimie et Ingénierie Moléculaire, Université d'Angers, CIMA UMR 6200, UFR Sciences, 49045 Angers, France.
Riobé
François
F
Sancho
Raquel
R
Minguíllon
Cristina
C
Avarvari
Narcis
N
D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D005030:Ethylenes / Q000737:chemistry; D006571:Heterocyclic Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000302:isolation & purification; D008958:Models, Molecular; D008968:Molecular Conformation; D011789:Quantum Theory; D012451:Safrole / Q000031:analogs & derivatives* / Q000737:chemistry; D013237:Stereoisomerism; D013379:Substrate Specificity
D005030:Ethylenes; D006571:Heterocyclic Compounds; C036216:ethylene; C063887:tetrathiafulvalene; D012451:Safrole; C005746:sulfoxide