Pyrimido benzothiazoles

Thiazolo[3,2-a]quinazolines.—[C3NS-C4N2-C6]. A number of thiazolo-[3,2-a]quinazolones have been obtained by the application of conventional cyclization reactions. Thus, the condensation of 2-mercapto-3-phenylquinazolin-4(3/f)-one (301) and phenacyl bromide yields the S -alkylated derivatives (302) which are reduced by sodium borohydride tol,2-dihydro-2-(a-hydroxyphenethyl)mercapto-3-phenylquinazolin-4(3/f)-one (303). Cyclodehydration by acetic anhydride or toluene-p-sulphonic 

Several 4-benzenesulphonyl-l-phenylthiazolido[3,2-n]quinazolin-5(4//)-ones (309) and thiazolo[3,2-a]quinazolonium salts (310) have been prepared by similar cyclizations.  

Thiazolo[4,5-6]quinoxalines.—[C3NS-C4N2-C ]. 2-Arylimino(and 2-imino-3-aryl)-2,3-dihydrothiazolo[4,5-6]quinoxalines (311) are accessible by the 

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IVapani, G., Carotti, A., Franco, M., Latrofa, A., Genchi, G. and Liso, G. (1993). Structure Affinity Relationships of Some Alkoxycarbonyl 2H-Pyrimido or Alkoxycarbonyl-4H-Pyrimido-(2,l-b)Benzothiazol-2-Qne or 4-Qne Benzodiazepine Receptor Ligands. EurJ.Med.Chem., 28, 13-21. 

A one-pot three-component reaction of 2-aminobenzimidazoles, aldehydes 71 and P-ketoesters 72 has been developed for the synthesis of 4//-pyrimido[2,l-6]benzothiazoles 75 <05BMCL5553>. The reaction presumably proceeds in two steps Knoevenagel condensation of 71 with 72 produces 3-benzylidene-2,4-pentanedione 73 Michael addition of 73 with 2-aminobenzothiazole then generates 74, which cyclizes to 75. 

Pyriniido[i,2-a]benzothiazol-2-one, 1010 Pyrimido[2.1-/>]benzothiazol-4-one, 1008 Pyriinido(2,l-6]benzoxazol-4Hme, 930 Pyrimido(4,5-r]dnnoline-1,3-dione, 12S7 Pyrimido(4.S C- -l -diazepiiie-6.8-dione, 1259... 

Related Reagents. 7-Chloro-l,2-dihydro-2-phenyl-imidazo [l,2-a]quinoline (Cl-PIQ), / -Enantiomer [863319-04-4]) 3,4-Dihydro-2-phenyl-2//-pyrimido[2, l-fi]benzothiazole (HBTM) 2-(A -Benzyl-7V-methylaminomethyl)- 1-methylpyrrolidine (/ -Enantiomer [540474-12-2], 5-Enantiomer [208833-00-5]) 4-Dimethylaminopyridinyl(pentaphenylcyclopentadienyl)rron (C5 Phs-DMAP, / -Enantiomer [187682-64-0], 5-Enantiomer [187596-69-6]). ... 

The syntheses of variably substituted 4(l//)-quinolones 449, 5//-thiazolo[3,2-a]pyrimidin-5-one (not shown), and 4//-pyrimido[2,l-fc]benzothiazol-4-ones 452 could be achieved by reacting substituted anilines 446 and the corresponding 2-aminothiazoles 450, respectively, with trimethylorthoformate 447 and Meldrum s acid 112 in the... 

Pyriniido[24-6]benzothiazole8 [CgNS-CiNj-Ce].—2-Aminobenzothiazole reacts with methyl propiolate in THF to give largely 2H-pyrimido[2,l-b]benzothiazol-... 

Pyrimido[5,4-g]benzothlazoles [CgNS-CiNa-Ce].—The a-hydroxymethylene ketone (121) reacts with benzamidine to give 8-methyl-5,6-dihydro-2-phenylpyrimido-[5,4- ]benzothiazole (122). ... 

Pyrimido[2,l-lb)benzothiazoles [C2NS-C N2-Cg] 192 Thiazolo[2,3-b]quinazolines [C2NS-C N2-Cgl 192 Thiazolo[3,2- ]quinazolines [C2NS-C N2-Cgl 193 Thiazolo[2,3- ]isoquinolines [C NS-CgN-Cgl 193 Thiazolo[4,5-fImorphans [C NS-CgN-Cg] 193... 

The ability of thiosemicarbazides, thiosemicarbazones, thiocarbohyd-razides, and their selenium analogues to undergo a variety of cyclization reactions has been further exemplified in recent syntheses of derivatives of 1,3,4-thiadiazoles, " 1,3,4-selenadiazoles, - l,3,4-triazole-2-thiones, " quinazoline-2-thiones, l,2,4-triazine-2-thiones, and pyrimido[2, l-b]benzothiazoles. ... 

Pyrimido[2,3-b]thiazolo[5,4-b]pyridines (C3NS-C4N2-C5N).—See thiazolo[5,4-blpyridines and pyrimido[2,l-b]benzothiazoles. 

Pyrimido[2,l-b]benzothiazoles (C3NS-C4N2-C6).—The condensation of 2-aminobenzothiazole and ethyl aceto(or benzoyl)acetate in polyphosphoric acid at 140 °C yields 2-substituted pyrimido[2,l-b]benzothiazoles (255). Diethyl ethoxymethylenemalonate yields substituted 4-oxo-3-(4H-pyrimido[2,l-b]benzothiazole)carboxylic acids (257), by way of the linear... 

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