海ホタルLuciferinおよび関連物質の合成研究(第6報) : 3-Hydroxyimidazo[1,2-α]pyridine類の合成

抄録

Condensation of 2-aminopyridine with benzaldehyde sodium bisulfite adduct and NaCN by the method of Ohta, et al. gave, instead of the nitrile as previously suggested, 3-amino-2-phenylimidazo[1, 2-α]pyridine (VI), which in turn was converted by treatment with conc. hydrochloric acid into 3-hydroxy-2-phenyl derivative (X). 3-Amino (IV) and 3-amino-2-methyl derivative (V) by the same treatment, however, gave the corresponding carboxylic acids (XI and XII). Instead of the unsuccessful cyclization of XI and XII, the ethyl ester of XII (XIV) was smoothly converted, on being heated in vacuo, to pure 3-hydroxy-2-methyl derivative (IX). It is interesting to note that the chemiluminescence activity is observed with 3-hydroxy compounds (VIII, IX and X), but not with 2-hydroxy-3-methyl derivative (III), which is synthesized from I and α-chloropropionyl chloride and exists in a tautomeric mixture of 2-hydroxy type (IIIb) and 2-keto type (IIIc) in a DMSO solution.