Thiazoles 2-aminobenzo

Thiazolo[5,4-/]quinoline 23 was prepared in 1949 starting from 6-aminobenzo-thiazole using Skraup reaction conditions glycerol, sodium 3-nitrobenzenesulfo-nate, and 78% sulfuric acid and heating at 110°C for 12 hours. Angular ring fusion... 

A direct procedure from isothiocyanates and amines using tetrabutylammo-nium thiocyanate (Bu4NSCN) and PhCH2NMe3Br3 affords functionalized 2-aminobenzo-l,3-thiazoles (Scheme 60).143... 

Aryl-2-thioureas (202) are an important source of aromatic fused-ring compounds. By far the most frequently encountered conversion of 202 to the latter are those leading to 2-aminobenzo[d]thiazoles (203),... 

Benzothiazoles have been prepared by oxidative condensation of aldehydes with resin-bound 4-mercapto-3-aminobenzoic acid derivatives (Entry 8, Table 15.18), and by dehydration of 2-mercaptoanilides (Entry 9, Table 15.18). Oxidation of 2,3-di-hydrobenzothiazoles to benzothiazoles can occur spontaneously, without the need of any additional oxidant [231]. Polystyrene-bound 4-iodobenzoate reacts with thiazole in the presence of Pd(0) to yield a 4-(4-thiazoIyl)benzoate (Entry 10, Table 15.18). If Cul is added to the reaction mixture, however, the 4-(2-thiazolyl)benzoate results [141]. 

Aminobenzo.thiazoles are alkylated on the ring nitrogen atom with a certain amount of (V-exocyclic alkylation whereas both 2-aminonaphtho-[l,2]- and -[2,l]-thiazoles give exclusively ring nitrogen methylation. 

The 1 1 cocrystal of 2-amino-5-nitrothiazole with 4-aminobenzoic acid comprises two constituent molecules associated by a hydrogen-bonded graph set dimer through the carboxylic group across the N/N site of the thiazole [0-H...N, 2.614(3)A N-H...O, 2.991(3)A] [144], 2-Bromo-5-nitrothiazole [145], tetrakis (mefa-acetato)bis[2-(2-thionyl)-amino-5-nitrothiazole]-dirhodium-II-dihydrate [146], and /V-(4-melhoxyben/yl (-/WS-nilro-1,3-thia/ol-2-yl) urea [147] have been studied by X-ray analysis. 

Type B Syntheses of Benzothiazoles (CfJBs-N-C-S). Following a known method, arylthioureas were oxidized to give substituted 2-aminobenzo-thiazoles and 2-[(2-thioxoimidazolidin)-3-yl] benzothiazole by bromine, and substituted 2-aminobenzothiazoles by SOCl2 or Br2 (CI2) and... 

Phenols and primary, secondary, and tertiary aromatic amines with free ortho- and/or /wra-positions react readily with thiocyanogen, (SCN)2. SCN enters the position para to the OH or NR2 group, or, if that is occupied, into the orfAtf-position.11,12 In the later case subsequent ring closure may be easy.14,760 For instance, / -toluidine gives 6-methylbenzo[A]thiazole-2-amine, and etyhl / -aminobenzoate gives ethyl 2-aminobenzo[Z ]thiazole-6-carboxylate. 

Joyce LL, Batey RA. Heterocycle formation via palladium-catalyzed intramolecular oxidative C—H bond functionalization an efficient strategy for the synthesis of 2-aminobenzo-thiazoles. Org. Lett. 2009 11 2792-2795. 

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