Thiazolo triazole, preparation

Dimethoxy-3-methyl-l-(4-nitrophenyl)-iV-(5, 6 -dihydrothiazolo[3,2-b][l,2,4]triazol-2 -yl)isoquinolinmm bromide 45 is also prepared by reacting 4,5-dimethoxy-2-(4-nitrobenzoyl)phenylacetone 219 with 2-amino-5,6-dihydro-thiazolo[3,2- ][ 1,2,4]triazole 42 <2003JHC821, 2003JHC1041> (Equation 23). 

Several polyheterocyclic compounds containing a condensed 1,2,4-triazole nucleus, such as 3,5-disubstituted thiazolo [2,3-r][ 1,2,4] triazoles, are thermostabilizers for polypropylene and polycaproamide <2003MI2>. Triazolo[3,4-A][l,3]benzothiazoledicarbonitrile derivatives are used to prepare hexazocyclanes-fluorophores as active media for liquid and solid lasers, scintillators, and for transformation of short-wave radiation to long-wave radiation <2004RUP2238276>. 

Thiazolo[3,2-h][l,2,4]triazoles have been prepared either from suitably substituted 1,2,4-triazoles [route (a)] or from 1,3-thiazoles [route (b)j. 

Mercaptotriazoles 133, available from thiosemicarbazones, are versatile starting materials for the preparation of thiazolo[3,2-h][l,2,4]triazoles. Treatment with a-halo ketones (and esters) yields S-alkylated derivatives that are cyclized to 134 either directly or on treatment with acidic catalysts (e.g., P2O5/H3PO4). 

The most commonly used method for the preparation of fused thiazoles involves the reaction of a-mercapto N-heterocyclic compounds of type (138) with an a-halocarbonyl compound or ester to give S-alkylated intermediates (139) which can be dehydrated to (140). When R2 is alkoxy, thiazolones (141) are formed (Hantzsch synthesis). Strong dehydrating agents are necessary to cyclize aldehydes and ketones (139) to fused thiazoles. The method has been used to prepare (dihydro) imidazo[2,l-6]thiazoIes and thiazolo[3,2- ]-s-triazoles (80JHC1321, 78JHC401, 82IJC(B)243). 

The oxidation of hydrazones of general structure (269) has been frequently used to prepare derivatives of s-triazolo[3,2-c]-s-triazole (68JOC143), oxazolo[2,3-c]-s-triazole and thiazolo[2,3-c ]-s- triazole (65JPR(30)280), lH-s- triazolo[4,3-[Pg.1014]

A variety of one-carbon cyclizing agents have been used (71JOC10) to prepare 3-substituted l,3-thiazolo[2,3-c] 1,2,4-triazoles (111) from 2-hydrazino-l,3-thiazoles (110). The acid hydrazides (113) of these hydrazines, prepared either directly from 110 and carboxylic acid derivatives or indirectly from 1-acylthiosemicarbazides (112) and a-haloketones, also undergo facile dehydrative cydization to 111. [71JOC10 78JHC401 ... 

Bhargava and co-workers [196] synthesized and studied the anti-inflammatory activity of some 3-(0-substituted phenyl)-4-substituted phenyl-5 alkyllalkenyl mercapto-lH-1,2,4-triazoles. Mohan and co-workers [197] synthesized and studied the antimicrobial activity of thiazolo (3,2-b)-S-triazole, S-triazolo (3,4-b) (1,3,4) thiodiazines and isomeric diazolo (2,3,-c)-S-triazoles. The compound 2,4-dihydro-l,2,4-triazole-3-thiones (disub-stituted in positions 4 and 5) were prepared [198] and used as bac-... 

Condensed 1,3f4-Thiadiazoles. - Triazolof3,4-b][1,3,4Jthiadiazoles and thiadiazolines are prepared by cyclisation of 3-mercapto-4-amino-1,2,3-triazoles with substituted alkyl carboxylic acids or treatment with HCl followed by reflux with aldehydes. Thiazolo[4,3-b]M,3,4Ithiadiazoles (368 R=Me,Ph,H,R =Ar) result from treatment of acyl rhodanines (367) with PCl. Further reactions of the former have been reported. Imidazo [2,3-b][1,3,4]-... 

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