CHEMISTRY AND SYNTHESIS OF SOME DIHYDRO-2H-l,4-BENZOTHIAZINE DERIVATIVES

Abstract

The formation of 3-oxo-3,4-dihydro-2H-1,4-benzothiazine ( I I I a ) by cyclization of allryl '3-haloacetarnidophenyl sulfides ( I ) was investigated; it is proposed that the reaction proceeds via a six-membered sulfonium halide. The preparation of 4-alkyl derivatives of IIIa and of 4-alliyl and 4-acyl derivatives of its reduction product 3.4-dihydro-2H-1,4-benzothiazine ( V a ) is described. Acylation of V a was shown t o proceed without opening of the thiazine ring.Preparation of the 0-benzoyl, N-benzoyl, and 0,N-dibenzoyl derivatives of 2-(8-hydroxyethylmercapto)aniline ( V I I I ) has permitted clarification of the confusion in the literat~ire with respect to the derivatives of V a and VIII.

Sodium Triethylborohydride-Catalyzed Controlled Reduction of Unactivated Amides to Secondary or Tertiary Amines

“…1 H NMR (400 MHz, CDCl 3 , 20 °C): δ 6.84 (t, J = 7.7 Hz, 1H), 6.78 (d, J = 7.9 Hz, 1H), 6.69 (d, J = 8.0 Hz, 1H), 6.61 (t, J = 7.6 Hz, 1H), 4.26 (t, J = 4.4 Hz, 2H), 3.38−3.31 (m, 4H), 1.16 (t, J = 7.1 Hz, 3H). 13 32 N-Methylaniline (3a). Purification by silica gel column chromatography using petroleum ether gave colorless oil, 45 mg, 84%.…”

Reactions of some 2-aminophenyl- and 2- and 4-nitrophenyl sulfones in aqueous sodium hydroxide solution

“…Although 3 could be prepared in solution, the acid could not be isolated owing to the ease with which it cyclized to the lactam, 3,4-dihydro-3-0x0-2H-1,4-benzothiazine-1 ,ldioxide (4) (3,4). Several attempts to prepare 3 by the published method ((5) reduction of 2-nitrophenylsulfonylacetic acid (5) with ferrous sulfate and ammonia) or by reduction of 5 with sodium Can.…”

Preparation of an aromatic hydroxylamine and some cyclic hydroxamic acids, and their reaction with hydrochloric acid

“…In the same way, the action of hydrogen chloride on 6-chloro-3,4-dihydro-4-hydroxy-3-0x0-2H-l,4-benzothiazine (9) gave an excellent yield of 6,7-dichloro-3,4-dihydro-3-oxo-2H-1,4benzothiazine (10). The structure of 10 was readily deduced from its n.m.r.…”

“…spectrum of which was superimposable on that of the product obtained in the reduction of 1 (method (iii)). (10) Hydrogen chloride was bubbled through a methanolic solution ( Reduction of (0-Nitropheny1thio)acetic Acid 4The title compound was reduced with sodium borohydride and palladium~harcoal in dioxane as described previously (3). The product, m.p.…”