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Synthesis of 5‐ethyl‐1,3,8‐trimethyl‐1H‐[5‐ 14 C] imidazo[1,2‐c]pyrazolo[3,4‐e]pyrimidine
Author(s) -
Hicks J. L.,
Huang C. C.
Publication year - 1985
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/jlcr.2580220911
Subject(s) - chemistry , pyrimidine , medicinal chemistry , yield (engineering) , imidazole , bromide , organic chemistry , stereochemistry , materials science , metallurgy
Abstract 5‐Ethyl‐1,3,8‐trimethyl‐1H‐imidazo[1,2‐c]pyrazolo[3,4‐e]pyrimidine, a new antipsychotic agent, was labeled with 14 C. The labeled compound was synthesized from barium [ 14 C]carbonate in four steps. [1‐ 14 C]propanoic acid, made from 14 CO 2 and ethylmagnesium bromide, was treated with 5‐(4,5‐dihydro‐4‐methyl‐1H‐imidazol‐2‐yl)‐1,3‐dimethyl‐4‐nitro‐1H‐pyrazole in the presence of dicyclohexylcarbodiimide to give 2‐(1,3‐dimethyl‐4‐nitro‐1H‐pyrazol‐5‐yl)‐4, 5‐dihydro‐4‐methyl‐1‐(1‐[1‐ 14 C]oxopropyl)‐1H‐imidazole. This was reduced and cyclized to 5‐ethyl‐7, 8‐dihydro‐1,3,8‐trimethyl‐1H‐[5‐ 14 C]imidazo[1,2‐c]pyrazolo[3,4‐e]pyrimidine. Oxidation gave the title compound in an overal radiochemical yield of 35% with a specific activity of 4.88 mCi/mmol.