Nitrilase mediated mild hydrolysis of a carbon-14 nitrile for the radiosynthesis of 4-(7-hydroxycarbamoyl-[1-14C-heptanoyl]-oxy)-benzoic acid methyl ester, [14C]-SHP-141: A novel class I/II histone deacetylase (HDAC) inhibitor

A strategy has been developed for the carbon-14 radiosynthesis of [¹⁴C]-SHP-141, a 4-(7-hydroxycarbamoyl-heptanoyloxy)-benzoic acid methyl ester derivative containing a terminal hydroxamic acid. The synthesis involved four radiochemical transformations. The key step in the radiosynthesis was the conversion of the 7-[¹⁴C]-cyano-heptanoic acid benzyloxyamide [¹⁴C]-4 directly into the carboxylic acid derivative, 7-benzyloxycarbamoyl-[¹⁴C]-heptanoic acid [¹⁴C]-8 using nitrilase-113 biocatalyst. The final step involved deprotection of the benzyloxy group using catalytic hydrogenation to facilitate the release of the hydroxamic acid without cleaving the phenoxy ester. [¹⁴C]-SHP-141 was isolated with a radiochemical purity of 90% and a specific activity of 190 μCi/mg from four radiochemical steps starting from potassium [¹⁴C]-cyanide in a radiochemical yield of 45%.