Said M. M. Bayomi

Sulfilimines in organic syntheses: new entries into tetrahydro-1,2-benzothiazepine and 1,2-benzisothiazole systems

Novel ring transformations of thiochroman-4-ones and benzo[b]thiophen3(2H)-ones to tetrahydro-1,2-benzothiazepin-5-ones and 1,2-benzisothiazoles via sulfilimine intermediates are described.

Conversions of thiochroman-4-ones into 1,2-benzothiazepine, benzo-[b]thiophen, and 1,2-benzisothiazole systems via sulphimide intermediates

Reaction of thiochroman-4-ones (1a–g) with chloramine-T gave the corresponding N-tosylsulphimides (2a–g) and sulphoxides (5a–g). The N-tosylsulphimides (2a–d), on reaction with triethylamine in chloroform, gave 2-tosyl-2,3-dihydro-1,2-benzothiazepin-5(4H)-ones (3a–d), but the 2-methyl congeners (2e and f) yielded 2-crotonoyl-N-tosylbenzenesulphenamides (4e and f). When the reaction was carried out in acetonitrile, (2e and f) afforded (3e and f) and (Z)-2-ethylidene-2,3-dihydrobenzo [b]thiophen-3(2H)-ones (7e and f). The 2,2-dimethyl derivative (2g) led to only (4g) and (7g). Heating (2a–c) in acetic acid gave Diels–Alder dimers (6a–c) of 2-methylidene-2,3-dihydrobenzo [b]thiophen-3-ones, and (2e–g), upon heating in chloroform containing acetic acid, gave (7e–g). S-Amination of (1a, b, and d–f) with O-mesitylenesulphonylhydroxylamine followed by alkaline treatment gave 3-vinyl-1,2-benzisothiazoles (11a, b, and d–f).

Synthesis and some properties of a new class of six membered heteroaromatic betaines, 3H-pyrido[3,2,1-ij][1,2,4]benzotriazin-4-ylium-3-ides

A series of 3H-pyrido[3,2,1-ij][1,2,4]benzotriazin-4-ylium-3-ides has been synthesised by reaction of 8-acylaminoquinolines with O-mesitylenesulphonylhydroxylamine followed by treatment with aqueous alkali. The spectral (u.v., 1H n.m.r., and 13C n.m.r. spectra) and chemical properties (bromination and 1,3-dipolar cycloaddition) of the new mesomeric betaines have been investigated.

Novel conversions of benzo[b]thiophen-3(2H)-ones into 1,2-benzisothiazole and tetrahydro-1,2-benzothiazepin-5-one systems via sulphimide intermediates

S-Amination of 2,2-dimethyl-(3a) and 2-benzyl-2-methyl-benzo[b]thiophen-3(2H)-one (3b) with O-mesitylene-sulphonylhydroxylamine followed by treatment with base yielded 3-isopropenyl-(4a) and 3-(1-benzylvinyl)-1,2-benzisothiazole (4b), respectively. Similar treatment of 2-methyl-2-phenyl-(3c) and 2-methyl-2-(p-chlorophenyl)-benzo[b]thiophen-3(2H)-one (3d) gave, in addition to the corresponding 3-vinyl-1,2-benzisothiazoles (4c and d), 4-phenyl-(5a) and 4-(p-chlorophenyl)-2,3,4,5-tetrahydro-1,2-benzothiazepin-5-one (5b), respectively. Reaction of (3a) with chloramine-T gave the corresponding N-tosylsulphimide (9) and sulphoxide (10). Refluxng the N-tosylsulphimide (9) in benzene in the presence of triethylamine causes rearrangement to 4-methyl-2-tosyl-2,3,4,5-tetrahydro-1,2-benzothiazepin-5-one (12a). When the reaction of chloramine-T was applied to (3c), as many as four products, the corresponding 1,2-benzothiazepine (12b), one N-tosylsulphimide (15), and two isomeric sulphoxides (16) were isolated. Reaction pathways are discussed.