Imidazo pyridin-4-thione

Imidazo[4,5-c]pyridine-2(3f7)-thione, 1-methyl-reactions with acrylonitrile, 5, 620 Imidazo[l,2-a]pyridine-2(3H)-thiones synthesis, 5, 632... 

Some general observations for 4-nitroimidazo[4,5- ]pyridin-2-ones, imidazo[4,5- ]pyridine-2-thiones, imidazo[4,5-f]pyridine-2-thiones, imidazo[4,5- ]quinolin-2-ones, isothiazolo[5,4- ]pyridine-2-thiones, and 3/f-l,2-dithiolo[4,3-f]pyridine-3-thiones are reported in <1996CHEC-II(7)283>. The majority of compounds in this review have been isolated using standard chromatographic techniques. 

Numereous derivatives of benzimidazole, naphthoimidazoles and other condensed imidazole systems can be very effectively thiated with elemental sulfur on heating without solvent at 230-260°C. The product of this reaction is the corresponding imidazolin-2-thione formed in excellent yield (67ZOR1518, 95IZV2231). For example, imidazo[4,5-cjpyridines (329, R =H, Aik, Ar, C6H5CH2) gave 1,3-dihydro-2//-imidazo[4,5-c]pyridine-2-thiones (330). 

The IR spectra of a large number of 2-thione derivatives of both imidazo[4,5-6]pyridine and imidazo[4,5-c]pyridine have been reported. In the study it was shown that these compounds exist... 

A study on the preparation of a relatively large number of imidazo[4,5-fr]pyridine-2-thiones and imidazo[4,5-c]pyridine-2-thiones demonstrates that the solubility of these compounds is poor in most solvents <88CHE653>. 

Michael addition of acrylonitrile to imidazo[4,5-c]pyridine-2(3//)-thione (134) gave l,3-bis(cyanoethyl)imidazo[4,5-c]pyridine-3(3//)-thione (135) (79MI41000). 

The thiolation of imidazo[4,5-c]pyridine (145) by heating with sulfur at 230-260 °C for 15-60 minutes gave imidazo[4,5-c]pyridine-2(3i/)-thiones (146), which can be desulfurized by heating at 50-90 °C with dilute nitric acid (71KGS428). 

Imidazo[4,5-c]pyridin-4(5//)-one (150) has been chlorinated with phosphorus oxychloride and thiated with phosphorus pentasulfide to give 4-chloroimidazo[4,5-c]pyridine (149) and imidazo[4,5-c]pyridine-4(5//)-thione (151), respectively (49RTC1013, 65JMC708). 

Cycloaddition of phenyl isothiocyanate (296) to pyridinium salts (295) produced imidazo[l,2-a]pyridine-2(3i/)-thiones (297) (77MI41001). Reaction of l-aryl-2-... 

Reaction of 3//-imidazo[4,5-y]quinoline-2-thione (404) with chloroacetic acid gives acid 405 which, on treatment with a mixture of acetic anhydride and pyridine, undergoes cyclization to furnish a product confirmed by the appearance of a band at 1735 cm (N—C=0) and molecular ion peak [M] at m/z 241. Thiazolo[2, 3 2,3]imidazo[4,5-y]quinolin-6(7//)-one (406), in preference to the other possible isomer thiazolo[3, 2 l,2]-imidazo[4,5-y]quinolin-8(7//)-one (409), was assigned to the cyclized product on the basis of the comparative studies of proton signals of the cyclized product (406 or 409) with those of 407 or 408 (obtained by the reaction of 404 and 1,2-dibromoethane), as well as with the proton signals of acid 405 [86IJC(B)264] (Scheme 93). 

Cycloaddition of phenyl isothiocyanate (296) to pyridinium salts (295) produced imidazo[l,2-a]pyridine-2(3//)-thiones (297) (77Ml4looi). Reaction of l-aryl-2-chloropyridin-6-ones with mono-A/ -substituted ethylenediamines provided dihy-droimidazo[l,2-a]pyridin-5-ones (79CPB1207). Another procedure involves the polyphos-phoric acid cyclization of 2-(2-hydroxyethyl)aminopyridines (76AJC1039). Treatment of certain /3-aminoacrylic esters (298) with benzenediazonium fluoroborate (299) resulted in... 

Microwave irradiation can be used to make oxazolo[4,5-fc]pyridines and allows reaction with amides in lieu of acids when urea or thiomea are used, 2-ones (2-thiones) are obtained carbon disulfide with potassium hydroxide also leads to 2-thiones. The use of triphosgene and 2,3-diamino-pyridines can be used to made the analogous imidazo[4,5-b]pyridin-2-ones. Reaction with cyanogen bromide gives... 

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