IDEAL ENANTIOMERIC RESOLUTION BY RECRYSTALLIZATION OF A RACEMIC COMPOUND .4. RELATIONSHIP BETWEEN ENANTIOMERIC RESOLUTION PHENOMENON AND CRYSTAL PROPERTIES

A new example of a racemate showing unusual enantiomeric resolution ph enomenon, in which simple recrystallization of the racemate leads to r emarkable enantiomeric enrichment of either enantiomer up to 100% ee i n the mother liquor, has been found. This compound is xypropoxy)phenyl carbamoyl]-ethyl]dimethylsulfonium p-nitrobenzene [EtOCH2CH(OH)CH2OC6H 4 NHCOCH2CH2SMe2+O2NC6H4SO3-] [(+/-)-SN]. By repeating recrystallizati on of (+/-)-SN and the resulting deposited crystals successively and c ollecting the resulting enantiomerically enriched mother Liquors with the same chirality sense, highly efficient enantiomeric resolution of the racemate into its separate enantiomers has been accomplished. The relationship between the occurrence of this enantiomeric resolution ph enomenon and the crystal properties has been investigated with respect to SN and its aryl- and alkylsulfonate derivatives, the mode of enant iomeric resolution of (+/-)-SN was similar to that of para-substituted benzenesulfonate derivatives (+/-)-ST (4-MeC6H4SO3-) and (+/-)-SC (4- ClC6H4SO3-) previously reported, whereas the unsubstituted derivative (+/-)-SB (C6H5SO3-) and alkylsulfonate derivatives (+/-)-SO (n-C8H17SO 3-) and (+/-)-SM (CH3SO3-) did not show such an enantiomeric resolutio n phenomenon, Tile crystalline form of the former racemates that: unde rwent tile enantiomeric resolution was racemic compounds, while the la tter were mixed crystals (solid solutions) composed of the respective optical antipodes. Chirality 9:220-224, 1997. (C) 1997 Wiley-Liss, Inc .