Thiepin 1,1-dioxide, 2,7-dihydro

Research utilizing the thiepine skeleton in material science has been reported. For example, liquid crystals with chiral dihydrodibenzo[c,i ]thiepines were studied. The enantiomerically pure (-)-(i )-3,9-bis[4-(dodecyloxy)benzoyl-oxy]-5,7-dihydro-l,l l-dimethyldibenzoR,f]thiepine 80 and (—)-(R)-3,9-bis[4-(dodecyloxy)benzoyloxy]-5,7-dihydro-1,1 l-dimethyldibenzoR,f]thiepine dioxide 82 display smectic C mesophases by a rigid twisted biphenyl core and axial chirality <1998JOC3895>. 

Racemic l,ll-dimethyl-5,7-dihydrodibenzo[c,< ]thiepine A-oxide 24 and A,A-dioxide 25 and 10,12-dihydro-4/7,6/7-[2]benzothiepino[6,5,4- i/][2]benzothiepine 30, based on bridged biphenyl structures, were resolved into enantiomers by chromatography on swollen microcrystalline TAC <2000HCA479>. The first-eluted enantiomers were assigned to have the (A)-configuration by comparison of the experimental CD spectra with spectra calculated by the CNDO/S method (see also Sections 13.03.3.1 and 13.03.3.3). 

The reaction of the complex (157) with divinyl sulphone gave the dihydro-thiepin 1,1-dioxide (159) instead of the expected triene (158) the latter is probably the primary product, and is converted into (159) by an intramolecular Diels-Alder reaction and subsequent isomerizations/° ... 

An unexpected feature of a sulphur analogue of the azepines, 4,5-dihydro-thiepin 1,1-dioxide (55), is the shortness of the C(ip )-C(sp) bonds (average 1.311 A). It is postulated that this effect may arise from the electronegative influence of the group. 

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