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Synthesis and Stereochemistry of Saturated and Partially Saturated 4‐Aryl‐4 H ‐3,1‐benzothiazine‐2(1 H )‐thiones
Author(s) -
Perjési Pál,
Földesi András,
Batta Gyula,
Tamás József
Publication year - 1989
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19891220411
Subject(s) - chemistry , benzothiazine , diastereomer , aryl , dehydration , stereochemistry , medicinal chemistry , hydrochloric acid , dehydration reaction , catalysis , organic chemistry , alkyl , biochemistry
The reaction of 2‐arylidenecyclohexanones 1 with dithiocarbamic acid gave three of the four possible diastereomers of 4‐aryl‐4a,5,6,7,8,8a‐hexahydro‐8a‐hydroxy‐4 H ‐3,1‐benzothiazine‐2(1 H )‐thiones 2 – 4 . The isomeric composition of the reaction products was found to depend on the quantity of hydrochloric acid used as catalyst. 1 H‐NMR studies showed that the preferred conformation of the cis isomers 2 and 4 is controlled by the bulky 4‐aryl group, which always occupies the energetically more favourable quasiequatorial position. Dehydration of 2 – 4 afforded the corresponding 4‐aryl‐tetrahydro‐4 H ‐3,1‐benzothiazine‐2(1 H )‐thiones 5 and 6 . The orientation of the dehydration reactions depends on the configuration of the starting compounds 2 – 4 and the reaction conditions used.