Optically active 1,3,2-benzodithiazole S-oxides : A study of rates of racemization and absolute stereochemistry

• The optical isomers of the 1-oxide, 1,3-dioxide and 1,1,3-trioxide, respectively, of 2-benzyl-1,3,2-benzodithiazole have been isolated by chiral liquid chromatography. The rate of racemization was found to be much higher for the monooxide as compared to the dioxide or trioxide. A first-order rate constant of 8.65 × 10-5 s-1 was calculated for the racemization of the 1-oxide in acetonitrile at 21°C. This corresponds to rate constants for the forward and reverse reactions in the enantiomerization process of 4.32 × 10-5 s-1 and a Gibbs' free activation energy of only 96.5 kJ mol-1 separating the enantiomers. The absolute configuration at the tricoordinated sulfur atom in the series of oxides was determined via an X-ray crystallographic structure determination of one of the diastereomeric 2-((S)-α-phenyl-ethyl)-1,3,2-benzodithiazole 1,3-dioxides.

Ämnesord

NATURVETENSKAP  -- Kemi -- Organisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Organic Chemistry (hsv//eng)

Nyckelord

1 3 2-benzodithiazole S-oxides

Absolute configuration

Chiral liquid chromatography

Enantiomerization barriers

Optical resolution

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