Sodium Hydroxide → 10H-pyrazolo[1',5':1,2]imidazo[4,5-c]quinoline

Participants

Reaction Conditions

Reaction Steps

A solution of tert-butyl N′-[3-(3,3-diethoxypropionylamino)quinolin-4-yl]-hydrazinecarboxylate (13.75 g, 32.9 mmol) and pyridinium p-toluenesulfonate (0.206 g, 0.082 mmol) in 1-propanol (250 mL) was placed under a nitrogen atmosphere and heated to 125° C. After 4 h, the reaction was cooled to ambient temperature and concentrated under reduced pressure to yield a dark red oily solid. This material was suspended in HCl (55 mL, 3 M in ethanol) and heated to 100° C. After 1.5 h, the reaction mix was cooled to ambient temperature and concentrated under reduced pressure to give a brown solid. The solid was suspended in water (50 mL), stirred vigorously, and neutralized with drop-wise addition of 10% NaOH aqueous solution until the pH of the liquid was 8. The aqueous mixture was transferred to a separatory funnel and extracted with chloroform (4×25 mL). The combined organic extracts were concentrated under reduced pressure to give a dark red solid. This solid was purified by prep. HPLC (350 g silica gel eluted with 1-20% CMA in chloroform) to give a dark red solid. This material was triturated with ether (75 mL) and filtered to yield 2.31 g of 10H-pyrazolo[1′,5′:1,2]imidazo[4,5-c]quinoline as a red solid.

Provenance & Evidence