反应详情

Reaction of 5 with formamide in excess at 190° C. for 8 h afforded the pyrazolo[3,4-d]pyrimidinone 10 which was purified by dissolving the crude in 2M NaOH, boiling with coal, followed by precipitation with acetic acid (yield 70%, m.p. 271-272° C.). Compound 11 was prepared in a yield of 44% following the Beal and Véliz9 procedure by treatment of 10 with a mixture of HMPT/NBS in acetonitrile at −20° C. followed by addition of LiBr and refluxing. It is interesting to point out that the secondary OH on the side chain remained unaltered by this procedure, as shown by its 1H NMR spectrum. Treatment of 11 with morpholine, butylamine, or piperidine gave the desired compounds 3a-c.

1. temperaturerefluxing