Ethyl 4-Oxo-4H-pyrimido[2,1-a]isoquinoline-3-carboxylate → Ethyl 6,7-Dihydro-4-oxo-4H-pyrimido[2,1-a]isoquinoline-3-carboxylate

Participants

Reaction Steps

A mixture of ethyl 4-oxo-4H-pyrimido[2,1-a]isoquinoline-3-carboxylate (2.68 g., 0.010 mole) in acetic acid (200 ml.) containing 10% palladium on carbon (1.0 g.) was shaken with hydrogen at an initial pressure of about 4 kg. cm.-2 until the theoretical pressure drop was reached (3.3 hours). The mixture was filtered and the filtrate flash evaporated to dryness to leave an oil, which upon dilution with toluene and reconcentration to dryness gave colorless crystalline material, m.p. 117°-125°. Two recrystallizations from ethanol raised the m.p. to 139°-141°. This material was combined with product of similar purity which separated from the first ethanolic mother liquor, and the lot recrystallized from cyclohexane to give the analytical sample, m.p. 138.5°-140°.

Provenance & Evidence