Thiazolo--triazines

2-Amino-A -selenazoline condenses similarly with ethoxycarbonyl isothiocyanate to give 2,3,6,7-tetrahydro-4if-selenazolo[3,2-a][l,3,5]triazin-2-one-4-thione (74 X = Se).  

Thiazolo[2,3-c][l,2,4]triazines [CaNS-CsNg].—Condensation of triazine (76 R = SEt) with chloroacetic acid gives 5,6-diphenyl-5fl -thiazolo[2,3-c][l,2,4]-triazin-3(lff)-one (77), which condenses with benzaldehyde to give the arylidene 

Thiazolo[3,2-6][l,2,4]triazines [CsNS-CsNs].— Investigations into the reactivity of 6-substituted 2,3-dihydro-7 -thiazolo[3,2-A][l,2,4]triazine-3,7-diones (78) have shown that, whilst condensation with aromatic aldehydes gives the 2-arylidene derivatives, the reaction with primary aromatic amines yields the corresponding 2,5-dihydro-3-arylamino[l,2,4]triazin-5-one, and not the expected anilides.  

Thiazolo[3,2-6]pyridaziiies [CsNS-C Ns].—a-Chloro-ketones interact with 3,6-dimercaptopyridazines to give the thiazoIo[3,2-6]pyridazinium salts [79 R = H 

Matsui, M. Nagano, J. Tobitsuka, and K. Oyamada, Chem. and Pharm. Bull. (Japan), 

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Treatment of phenylhydrazonothiazolidinone 663 with phenacyl bromide gave 664, which was cyclized [84MI2, 84ZN(B)390) to give thiazolo-triazine 665. Cyclization of 663 with ethyl bromoacetate afforded 662 (Scheme 136). 

Formamidinoyl isothiocyanates (157) combine with 2-aminothiazoles the ring nitrogen attacks the spC part of the electrophilic reagent (312) further reaction then yields aza-condensed thiazolo-s-triazines (158) (Scheme 99) (313). Mesoionic S-alkvlthiazolo[3.2-fl]-i-tria2ine-5,7-diones (159) are obtained when 2-alkylaminothiazoles react with phenoxycar-bonyl isocyanate (304). 

The synthesis of 9H-benzo[2,l-e]thiazolo-[2,3-c]-as-triazine (401) was achieved by oxydative cyclization of 2-imino-3-(o-aminophenyl)-4-phenyl-4-thiazoline (718, 719). This latter reacts also with paraformaldehyde in hot toluene yielding 3-phenyl-9H.10H-benzo[l,2-/]thiazolo-[2,3-d][l,3,5]triazepine (402) (720). This heterocyclic sytem is also formed when carboxylic acids replace paraformaldehyde (Scheme 230) (721). 

Thiazolotriazines 636 (R = CO,Me) were prepared [84JCS(P1)2707] by cycloaddition of dimethyl acetylenedicarboxylate with triazine derivative 632. Derivatives of thiazolo[3,2-b][l,2,4]triazin-3,7-diones 637 have been formed (74JPR163) on reaction with aromatic aldehydes and diazonium salts to give 636 (R = Ar) and 638, respectively. Regioselective catalyzed... 

Thiazolo[2,3-c][l,2,4]triazines 658 were prepared (84LA1302) regio-specifically by cyclizing 2-hydrazono-2-thiazoline 659 with glyoxylic acid or ester. They had herbicidal activity. Condensation of 659 with oxamic acid ethyl ester gave hydrazide 660, which was cyclized with sodium... 

Thiazolo[2,3-c][l,2,4]triazines 667 were synthesized by coupling the diazotized thiazole derivative 666 with activated nitriles to give 667 without... 

The reaction of 6-amino[l,2,4]triazin-5(2//)-ones or its thione derivatives 680 with acetic anhydride gave the 6-acetamido derivatives 681 and 682, respectively. Treatment with phosphorus pentasulfide in pyridine gave thiazolo[5,4-e][l,2,4]triazines 683 (84LA283 87AJC491) (Scheme 142). 

Cyclocondensation of 632 with dibromoethane in the presence of sodium ethoxide gave 2,3-dihydro-6-benzyl-7//-thiazolo[3,2-h][l, 2,4]triazin-7-one, whose structure was confirmed by X-ray analysis (91MI7). 

Naphtho[l, 2 4,5]thiazolo[3,2-h][l,2,4]triazines 1052 were prepared by cyclocondensation of aminoiminonaphthothiazole 1051 with an acetylenedicarboxylate. Methyl ester 1052 was tested in vitro for anti-HIV activity and was inactive (91MI6). 

Propargylmercapto-6-methyl-l,2,4-triazin-5(2fl)-one 85 cyclises to the thiazolo[3,2-6] [l,2,4]triazin-7-one 86 which can be brominated, and subsequently aminated, yielding the products 87 <95MI06 96CA(124)176024>. 

Novel three-component reactions of thiazole Schiff bases, ammonium acetate and aromatic aldehydes under solvent-free microwave irradiation conditions yielded diastereoselectively thiazolo-s-triazines <06GC455>. 

Aminomethylation of 2-ami no-5,5-bis(hydroxymcthyl)-l,3-thiazol-4(5//)-onc and its spiro analogs gave the corresponding [l,3]thiazolo[3,2-o][l,3,5]triazine derivatives <06CHE1086>. 

The electrochemical oxidation of catechols in the presence of 6-methyl-1,2,4-triazin-3-thion-5-one and 4-amino-6-methyl-l,2,4-triazin-3-thion-5-one as nucleophiles in aqueous solutions provided an efficient electrosynthesis of thiazolo[3,2-6][l,2,4]triazin-7-one and l,2,4-triazino[3,4-/)J 1,3,4-thiadiazinc derivatives respectively <06TL1713> <06TL8553>. 

Alkylation of 694 with phenacyl bromides, followed by cyclization with acetic anhydride gave (87H2183) thiazolo[2,3-c]pyrido[2,l-/][ 1,2,4]-triazine 695. 

Cyclization of imidazo[4,5-e][l, 2,4]triazine 766 with bromoacetic acid and aromatic aldehydes gave (80URP765270) octahydroimidazo[4,5-e]-thiazolo[3,2-6][l,2,4]triazin-3,7-diones 767. 

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