Synthesis of 5-ethyl-2-{5-[4-(2-hydroxyethyl)piperazin-1-ylsulfonyl]-2-n- propoxyphenyl}-7-n-propyl-3,5-dihydro-4H-pyrrolo[3,2-d]-[2-¹⁴C] pyrimidin-4-one · 2 HCl (¹⁴C-SK3530 · 2 HCl)

A new ¹⁴C-labelled PDE5 inhibitor, 5-ethyl-2-{5-[4-(2- hydroxyethyl)piperazin-1-ylsulfonyl]-2-n-propoxyphenyl}-7-n-propyl-3, 5-dihydro-4H-pyrrolo[3,2-d]-[2-¹⁴C]pyrimidin-4-one · 2 HCl (¹⁴C-SK3530 · 2 HCl) (1-2 HCl) was synthesized through a straightforward six-step sequence from the readily available [ ¹⁴C-carbonyl]methyl salicylate (2). The overall radiochemical yield of the 1 · 2 HCl from 2 was 10.5%, and its radiochemical purity was 98.8%.