Imidazo pyridine, dimethyl

Imidazo[4,5-6]pyridine, 1,2-dimethyl-methylation, 5, 618 Imidazo[4,5-6]pyridine, 2,3-diphenyl-synthesis, 5, 636 Imidazo[4,5-6]pyridine, 6-halo-alkylation, 5, 616 aminomethylation, 5, 616 Imidazo[4,5-6]pyridine, 2-(4-hydroxy-6-methylpyrimidin-2-ylamino)-synthesis, 5, 637... 

Imidazo[4,5-c]pyridine, 2,3-dimethyl-radical alkylation, 5, 621 Imidazo[4,5-c]pyridine, 2-ethoxy-synthesis, 5, 635... 

Imidazo[l,2-a]pyridines are formed by condensation of iV-arylacetylimidazoles with dimethyl acetylenedicarboxylate, [ 154H156]... 

A Vilsmeier reaction of pyridine-2-carbonitriles 126 was found to produce mixtures of l-formyl-2-dimethyl-amino[l,5-4]pyridines with a chlorine atom 127 or a hydrogen 128 at the C-7 position < 1998J(P 1 )3851 >. When extended to isoquinoline-1 -carbonitriles such as 129, this reaction gave in modest yield compounds 130 (Scheme 40). Later on, it was demonstrated that this reaction leads to imidazo[l,5- ]pyridinium chlorides when A,A-dimethylbenzamides were used instead of dimethylformamide (DMF) <1999H(50)887>. 

Amino-2,3-dimethyl-3//-imidazo[4,5-fc]pyridine was reacted with EMME in boiling toluene for 2 hr to afford 7V-(imidazopyridin-5-yl)amino-methylenemalonate (91) in 84% yield (86EUP174832). The reaction of 3-amino-4,6-dimethyl- l//-pyrazolo[3,4-6]pyridine and EMME yielded N-(4,6- dimethyl -1 //- pyrazolo[3,4 - 6]py ridin- 3 - y l)aminomet hy lenemalonate (92) (87MI5). 

Z-aminO 1 -methy 1 6 phenylimidazo [4,5-b]-pyridine 2 aminO 3,7,8 trimethylimidazo[4,5 f]quinoxaline 2 aminO 3,4,7,8 tetramethyl 3H imidazO [4,5 f]quinoxaline inoxaline 3 aminO l,4 dimethyl SH pyrid [4,3 b] indole (Trp P I) and 3 aminO l methyl 5H pyrido [4,3 b]indole induced mutagenesis. Metabolic activation was required for positive results b... 

Die basenkatalysierte Umsetzung kann auch in Nitrobenzol mil Pyridin als Katalysator [Her-stellung von mehreren 1-(3-Aryloxy-2-hydroxy-propyl)-2-methyl-4-nitro-imidazo-len 38-58%]87t, ohne Losungsmittel mit Kaliumcarbonat als Katalysator [l-(3-ChIor-2-hydroxy-propyl)-2-methyl-4-nitro-imidazol 60%]872 oder in Ethanol mit Natriumhydroxid als Katalysator [l-(2-Hydroxy-ethyl)-2-methyl-4-nitro-imidazol 100%]873 durchgefuhrt we.r-den. Statt Oxiran kann auch 2-Oxo-l,3-dioxolan eingesetzt werden. Dabei entstehen ohne Katalysator bei 160° die 1,4-Regioisomeren [z. B. 2,5-Dimethyl-l-(2-hydroxy-ethyl)-4-nitro-imidazol 60%]874... 

While imidazo[4,5-c]pyridine and its 1- and 3-methyl derivatives are resistant to nitration, imidazo[4,5-c]pyridin-2-one and its 1-methyl, 3-methyl, and 1,3-dimethyl derivatives have been readily nitrated at the 4-position (i.e. (152)) <86KGS97>. If the 4- and 6-positions are substituted, as in compound (153), then nitration occurs at the 7-position (e.g. (154)) <87JMC1746>. 

Furan 2-Aminomethyl-5-(2,4-dioxo-1,2,3,4-tetrahydro-pyrimidino)-2,5-dihydro- IV/lc, 578 Imidazo(l,2-a]pyridin 1,5-Dimethyl-8-nitro-7-oxo-l,2,3,7-tetrahydro-E15/3, 2790 [cycl. (R2N)2C = CH-N02 4- Diketen] 1,3-Oxazol 4-Cyan-5-(diethoxy-methylen-amino)- E4, 565 (Het — NH2 + Orthoester) Pyrazin 3-Amino-2-methoxycarbo-nyl-5-propanoyl- E9b/2, 324 (H - CO-R)... 

Reaction of imidazo[4,5-fc]pyridine (97), but not its 5-amino derivative, with perphthalic acid (49JA1885) or hydrogen peroxide in acetic acid (66UC403) gave the A( -oxide (98). Peracetic acid was used to prepare the A7 -oxides of 6-bromo-, 6-chloro, 6-bromo-5- and -7-methyl-, and 5,7-dimethyl-imidazo[4,5-fc]pyridine (98) (59JOC1455). The N-oxides can be catalytically reduced to (97) (80JHC17S7). 

Preparation of l,3-dimethylimidazo[4,5-c]pyrimidinium iodide (133) was accomplished by the lithium aluminum hydride reduction of l,3-dimethylimidazo[4,5-c]pyridin-2(3//)-one (132), prepared by the methylation of imidazo[4,5-c]pyridin-2(3//)-one with dimethyl sulfate (74KGS854), rather than by methylation of (128) or (130) (79MI41001). 

Radical alkylation of 1-methyl-, 3-methyl- and 2,3-dimethyl-imidazo[4,5-c]pyridine (147) takes place at C-4 giving (148) with some dimethylation of monomethyl compounds occurring, the second methylation being at C-2 (77KGS933, 78MI41006). 

Furthermore, it has been shown that compounds of type 235 are versatile starting materials for addition and cyclization reactions employing reactive triple and double bonds. With methyl propiolate, syn addition takes place to aiford the adducts 240. In the presence of alcohols, compounds 240 are cyclized to give the imidazo[l,2-a]pyridines and pyrido[l,2-a]pyrimidines 241136 (Scheme 63). By treatment with methyl acrylate, the lactone derivatives 235 give the spiro compounds 242 in an addition and cyclocondensation sequence.137 With dimethyl acetylenedicarboxylate, 235 forms several condensed and unsaturated spiro compounds 243, similar to 242,137 as well as the tricyclic 5-lactone 244 (Scheme 64). 

Tikkanen, L. M., Sauri, T. M., and Latva-kala, K. J., Screening of heat-processed Fitmish foods for the mutagens 2-amino-3,8-dimethyl imidazole [4,5f] quinoxahne, 2-amino-3,4,8-trimethyl imidazole [4,5f] quinoxahne and 2-amino-l-methyl-6-phenyl imidazo [4,5b] pyridine. Food Chem. Toxicol, 31, 717-721, 1993. 

AaC = 2-amino-9Tf-pyrido[2,3-fe]indole MeAaC = 2-amino-3-methyl-9Tf-pyrido[2,3-fe]indole Glu-P-1 = 2-amino-6-methyldipyrido[l,2-a 3 ,2 -ai] imidazole Glu-P-2 = 2-aminodipyrido[l,2-a 3 ,2 -ii]imidazole PhIP = 2-amino-l-methyl-6-phenyl-lH-imidazo[4,5-i)]pyridine IQ = 2-amino-3-methyl-3//-imidazo[4,5-/ quinoline MelQ = 2-amino-3,4-dimethyl-3Tf-imidazo[4,5-/ quinoline Trp-P-1 = 3-amino-l,4-dimethyl-5Tf-pyrido[4,3-i)]indole Trp-P-2 = 3-amino-l-methyl-5//-pyrido[4,3-I>]indole. 

The synthesis of [2.2.3]cyclazines, aza[2.2.3]cyclazines and their derivatives has also been covered. The attention of the reviewers has been focused on the study of the developments in the synthesis of several benzocyclazines and azacyclazines by the [8 -I- 2] cycloaddition reaction of the dimethyl acetylene dicarboxylate with various types of indolizines. The synthesis of indolizines, imidazo[l, 2-a]pyridines, and related compounds, which are key intermediates for the synthesis of cyclazines, is also described <88H(27)225i>. 

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