Syntheses of 1,5,6‐trimethyl‐2‐aminoimidazo[4,5‐b]pyridine and 3,5,6‐trimethyl‐2‐aminoimidazo[4,5‐b]pyridine

Abstract

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Identification of 2-Amino-1,7-dimethylimidazo[4,5-g]quinoxaline: An Abundant Mutagenic Heterocyclic Aromatic Amine Formed in Cooked Beef

“…The use of activated di(imidazole-1-yl)methanimine (24) or S-methyl(isothiourea) (25) derivatives as cyclo condensing reagents, instead of CNBr, also resulted in poor yields of compound 5a. Low product yields have similarly been reported for the CNBr-ring-closure step of the diamine precursors of PhIP (26) and several other HAAs (25).…”

Synthesis of two potential heterocyclic amine food mutagens

“…The reaction was not suitable to be able to prepare enough material to complete the synthesis. Treatment of 14 with 70% hydrogen peroxide in sulfuric acid provided 3bromo-5,6-dimethyl-4-nitropyridine (16) in 32% yield. At room temperature treatment of 16 with aqueous methylamine resulted in displacement of the nitro group with methylamine to give 3-bromo-5,6-dimethyl-4-(methylamino)pyridine (17).…”

“…The mixture was extracted with chloroform (3 × 50 mL), dried (sodium sulfate), and filtered. Evaporation of the solvent left 1.19 g of crude material, which was Kugelrohr distilled to give 158 mg (10%) of 70% pure product (15); bp 95-105° at 2 mm of mercury; 1 3-Bromo-5,6-dimethyl-4-nitropyridine (16). A suspension of 6.5 g (32.3 mmoles) of 4-amino-3-bromo-5,6-dimethylpyridine (14) in 25 mL of concentrated sulfuric acid was heated to 90˚.…”

“…From the available preliminary data, the mutagenic compound has been determined to be one of the twelve isomers of 2-amino-trimethylimidazopyridine (TMIP) [11,14]. To investigate the biological risk associated with ingesting this unidentified compound, we have previously synthesized eight of the possible isomers: 2-amino-1,5,6-trimethyl-3H-imidazo [4,5-b]pyridine; 2-amino-3,5,6-trimethyl-3H-imidazo [4,5-b]pyridine [16]; 2-amino-3,5,7-trimethyl-3H-imidazo [4,5-b]pyridine; 2-amino-1,4,7-trimethyl-3H-imidazo [4,5-c]pyridine; 2-amino-1,6,7-trimethyl-3H-imidazo [4,5-c]pyridine; 2-amino-3,4,6-trimethyl-3H-imidazo [4,5-c]pyridine [17], 2-amino-1,4,6-trimethyl-3H-imidazo [4,5-c]pyridine and 2-amino-1,5,7-trimethyl-3H-imidazo [4,5-b]pyridine [18]. We now report the syntheses of two other possible isomers-2-amino-3,6,7-trimethyl-3H-imidazo [4,5-b]pyridine (1) and 2-amino-3,6,7-trimethyl-3H-imidazo [4,5-c]pyridine (2)-so that they can be compared and tested against the unknown mutagen.…”

Six‐Membered Heterocycles: Pyridines

“…The 2-aminopyridine 192 is finally obtained after a work-up with water.More vigorous conditions are required for the amination of alkylpyridines because proton abstraction from the side-chain by the amide ion occurs preferentially, and therefore ring attack must involve a dianionic intermediate. Nonetheless, 4-alkyl pyridines 197 have been successfully aminated at 150 C to afford reasonable yields of 2-aminopyridines 198 (Scheme 16.57)[166,167].…”