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Selective monosulfoxidation of tetrathiafulvalenes into chiral TTF‐sulfoxides
Author(s) -
Chas Marcos,
Riobé François,
Sancho Raquel,
Minguíllon Cristina,
Avarvari Narcis
Publication year - 2009
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20692
Subject(s) - chemistry , tetrathiafulvalene , enantiopure drug , sulfoxide , triclinic crystal system , enantiomer , oxaziridine , sulfonyl , crystallography , circular dichroism , crystal structure , photochemistry , stereochemistry , molecule , organic chemistry , enantioselective synthesis , catalysis , alkyl
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. Chirality, 2009. © 2009 Wiley‐Liss, Inc.