Chlorination of Heterocyclic and Acyclic Sulfonhydrazones

Abstract

Chlorination of 2H-1,2,3-benzothiadiazine 1,1-dioxide(1) in wet methylene chloride gives o-formylbenzenesulfonyl chloride (4), but in dry methylene chloride at 0° yields the chlorosultine 3-chloro-3H-2,1-benzoxathiole 1-oxide (2); the latter is readily hydrolyzed to the "pseudo-acid" 3H-2,1-benzoxathiol-3-ol 1-oxide (3) which on further chlorination forms 4. In 1,2-dichloroethane at −20° chlorination of 1 gave the "coupled product" 14, whereas in dimethylformamide at room temperature the cyclic acyl chloride hydrazone 4-chloro-2H-1,2,3-benzothiadiazine was isolated in poor yield. The acyl chloride hydrazones (16) were the products obtained following chlorination of some representative aromatic acyclic tosylhydrazones (15). 3H-2,3,4-Benzothiadiazepine2,2-dioxide (19), a previously unknown heterocyclic system, was synthesized in two steps from 1,3-dihydrobenzo[c]thiophene (17). Chlorinolysis of 19 gave o-chloromethylbenzal chloride (21). These reactions are believed to involve formation of the α-chloroazo compound (e.g. 22) as the first step. The formation of 2 from 1 is discussed in terms of three possible routes, two which involve the sulfene 23.

Chemistry of an Unexplored Heterocyclic Ring System: Versatile Synthesis of 5‐Aryl‐2,3,4‐benzothiadiazepine 2,2‐dioxides

“…The structure of 16 has been proven by X‐ray diffraction (see the Supporting information). A similar ring contraction was observed by King et al when compound 6a was heated at 175–180°C for 5 min .…”

“…The syntheses of phthalazines ( 1 ) , phthalazinones ( 2 ) , 2,3‐benzodiazepines ( 3 ) , and 2,3‐benzodiazepine‐4‐ones ( 4 ) are well elaborated. However, while numerous 1,2,3‐benzothiadiazine 1,1‐dioxides ( 5 ) have been synthesized, the only representative of the homologous 2,3,4‐benzothiadiazepine 2,2‐dioxide family described in the literature is the unsubstituted congener, that is, compound 6a itself (Scheme ) . Moreover, it is noteworthy that apart from 6a , there is no other compound described in the literature that corresponds to the general structure 6 (2,3,4‐benzothiadiazepine and related compounds).…”

“…Compound 6a was prepared more than 40 years ago with the aim of studying the chlorination reactions of “heterocyclic sulfonhydrazones.” It was obtained by cyclization of (2‐formylphenyl)methanesulfonyl chloride ( 7 ) with hydrazine (Scheme ) . Sulfonyl chloride 7 was produced by treatment of an aqueous suspension of 1,3‐dihydro‐benzo[ c ]thiophene ( 8 ) with chlorine.…”

Intramolecular Reversible Addition Reactions to the C=O Group

“…Thus, both isomers (41A) and (41B) of 2-formyl (R = H) [182] and 2-benzoylbenzenesulfochloride (R = Ph) [183,184] were obtained. IR spectroscopy shows that both isomers (41A, Unlike the 2-formylbenzenesulfochloride isomers (41A, R = H) and (41B) [182], which are stable in solutions, 2-formylbenzenesulfinylchlorides (42A) are subject to a ring-chain equilibrium (KT -0.25) in CD2Cl2 solution as has been shown by IH-NMR investigations [185].…”

Synthesis and Chemistry of 1,2,3-Benzothiadiazine 1,1-Dioxide Derivatives: A Comprehensive Overview

“…Depending on the reaction conditions, various reaction sequences involving chlorination, nitrogen extrusion, hydrolysis, ring opening, etc. led to compounds 48-52 [40]. Thermolysis of 1a at 500 °C in a quartz tube gave sultine 53 in 25% yield [14].…”