Novel synthesis of 2-arylbenzothiazoles

Abstract

A no',; method for the synthesis of 2-i~rylbcnzotttiazolcs b.v tllc rc:tctiun of dibcnz).l distlll]dc>: ~iill o-aminotl+iJophcnol is stlggcstcd. A possible mcchanixm el the nc~v trai++sibrnlat[Oll is disctr-:.scd. 2-1:'hcllylhcrtzothiazolc cdii also be prepared b.', rc,ictiotlx of ;s-:lmillolhiopl'lenol v+ith hcn&l mcrcaptanc or sodium hcnz.vi ttliosull~lte.

Microwave-assisted one-pot synthesis of benzothiazole and benzoxazole libraries as analgesic agents

“…31 Apart from these general methods, there have been many methodologies disclosed in the literature for the construction of benzothiazoles. [32][33][34][35][36][37][38][39][40] On the other hand, the classical approach for the synthesis of benzoxazoles involves (i) coupling of carboxylic acids with 2-aminophenols by dehydration catalysed by strong acid; 41 and (ii) the oxidative cyclization of phenolic Schiff's bases derived from the condensation of 2-aminophenols and aldehydes, using various oxidants such as PhI(OAc) 2 , 42 Mn(OAc) 3 , 43 ThClO 4 ,44 Ba(MnO 4 ) 2 , 45 NiO 2 ,46 Pb(OAc) 4 , 47 DDQ, 48 NIS, 49 Cu-np, 50 aerial oxidation in the presence of activated carbon (Darco KB), 51 CuCl 52 and Pd/Pt-C. 53 Other synthetic routes for benzoxazole include microwaveassisted reaction of N -acyl-aminophenol, 54 iron catalysed intramolecular O-arylation of 2-haloacetanilides 55 and cyclization of phenolic Schiff base under UV irradiation. 56 Apart from these methodologies, there have been many precedents for the synthesis of 2-aryl benzothiazoles and benzoxazoles via palladium catalysed cross-coupling reactions have been disclosed in the literature.…”

An efficient palladium catalyzed synthesis of 2-arylbenzothiazoles

“…[8][9][10] Other general methods include microwave mediated reaction of o-aminothiophenol with b-chlorocinnamaldehydes, reaction of dibenzyl disulfides with o-aminothiophenol, reduction of o,o%-dinitrodiphenyl disulfide, reaction of S-aryl thiobenzoate with arylhaloamines, from 1,2,3-benzodithiazole-2-oxides, radical cyclization of benzyne intermediates and Grignard reactions of arylisothiocyanates. [11][12][13][14][15][16] However, most of the above methods require multistep synthesis and therefore, we have sought to develop a convergent strategy for the synthesis of 2-arylbenzothiazoles. Our method utilizes a Suzuki cross coupling of the common intermediates 2-bromobenzothiazole (1) and 2-bromo-6-methoxybenzothiazole (2) with various aryl boronic acids/ esters as the key step (Table 1).…”

Synthesis of aromatic heterocycles

“…176 2-Arylbenzothiazoles have been formed from the reaction of 2-aminothiophenol with dibenzyl disulfides in DMF. 177…”