Synthesis of 1-Substituted 5-Aminoimidazole-4-carbaldehydes and 8-Amino-1-(2-fluorobenzyl)imidazo[4’,5’:5,6]pyrido[2,3-d]pyrimidine

Abstract

Synthesis of 1-Substituted 5-Aminoimidazole-4-carbaldehydes and 8-Amino-1-(2-fluorobenzyl)imidazo[4',5':5,6]pyrido[2,3-d]pyrimidine S y n t h e s i s o f 1 -S u b s t i t u t e d 5 -A m i n o i m i d a z o l e -4 -c a r b a l d e h y d e sAbstract: The syntheses of a number of 1-substituted 5-aminoimidazole-4-carbaldehydes 3, by the reduction of the corresponding 5amino-4-cyanoimidazole derivatives is reported using Li-AlH(OEt) 3 , prepared in situ from LiAlH 4 and ethyl acetate. The compounds of type 1 are useful intermediates for the synthesis of elongated adenine derivatives.Although a variety of conditions have been reported 1-3 for the reduction of heterocyclic nitriles to aldehydes, to our knowledge, the only reported synthesis of 5-aminoimidazole-4-carbaldehydes 3 (R 1 = R 2 = Me; R 1 = Me, R 2 = Ph) is by the catalytic hydrogenation of the corresponding 4aminoimidazole-5-carbonitriles using 10% Pd/C in dilute sulfuric acid. 4 These compounds have been shown to be useful reagents for the synthesis of imidazo[4,5-b]pyridine derivatives. 4 B. L. Booth et al.

Efficient Synthesis of 3H-Imidazo[4,5-b]pyridines from Malononitrile and 5-Amino-4-(cyanoformimidoyl)imidazoles

“…Most of the synthetic methods that were used for the preparation of imidazo[4,5- b ]pyridines generate the imidazole ring from a substituted pyridine, under suitable reaction conditions. 1a,, Examples where the pyridine ring is built from a conveniently substituted imidazole 7c, are not as common.…”