Radiolabeling of two 11C‐labeled formylating agents and their application in the preparation of [11C]benzimidazole

Abstract

The radiolabeling of formyl groups with carbon‐11 has so far been awarded little attention in the literature. We report here the preparation of the methyl and trifluoroethyl esters of [11C]formic acid and their use as 11C‐formylating agents in the preparation of [11C]benzimidazole. Methyl‐ethyl and trifluoroethyl [11C]formates were obtained in 36–45% radiochemical yield using a two‐step two‐pot process starting from [11C]carbon dioxide. The analytical radiochemical yield of [11C]benzimidazole using each of these two 11C‐formylating agents exceeded 96%. Given the high yields of the 11C‐formylating agents as well as the high yield of [11C]benzimidazole following their application, we expect these agents to find utility for a wider range of substrates.