(±)-4-Thiacarnegin (3) was synthesized by reaction of 6,7-dimethoxy-3-methyl-2 H-1,3-benzothiazinium iodide (2) with methyl magnesium iodide, thereby opening a new synthetic route to 4-substituted dihydro-2 H-1,3-benzothiazines. Compound 3 was also obtained by reduction of 6,7-dimethoxy-3,4-dimethyl-2 H-1,3-benzothiazinium iodide (5). In a similar way, reduction of the quaternary salts 9 a-c afforded the (±)-4-thia analogues of cryptostilin-I, -II and -III (10 a-c). The isomers of the former compounds (12 a-c) were also synthesized by reduction of the 4 H-1,3-benzothiazinium salts 11 a-c.
- 2 H-1,3-Benzothiazines
- 3,4-Dihydro-2 H-1,3-benzothiazines
- 4 H-1,3-Benzothiazines
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