含窒素環化合物の合成 (第116報)

オキサゾロピリジン類およびその関連化合物の合成 その2

抄録

1) 3-Amino-4-hydroxy-5-bromopyridine (II) was heated with acid anhydrides and 3-acylamino-4-hydroxy-5-bromopyrimidines (III to VI) and 2-alkyl (or aryl)-7-bromoxazolo[4, 5-c]pyridines (VII to X) were prepared. The latter compounds were converted to the corresponding monomethiodides (XI to XIV) by reaction with methyl iodide.
2) Reaction of (II) with potassium methylxanthate in methanol afforded 2-mercapto-7-bromoxazolo[4, 5-c]pyridine (XV) which was reacted with alkyl halides to form the corresponding thioethers (XVI to XVIII).
3) Reaction of (II) with cyanogen bromide, either in anhyd. ethanol or water, afforded 3-cyanamido-4-hydroxy-5-bromopyridine and not 2-amino-7-bromoxazolo-[4, 5-c]pyridine. It was assumed that, in this case, a reaction between (II) and diethyl iminocarbonate, formed by the reaction of ethanol and cyanogen bromide, might occur to produce 2-ethoxy-7-bromoxazolo[4, 5-c]pyridine as a by-product but the latter compound was not isolated.