PROCESS FOR PRODUCTION OF (S) -N-PENTANOYL-N-[[2'-(1H-TETRAZOLE-5YL) [1,1'-BIPHENYL]-4-YL]METHYL]-L-VALINE

摘要

The patent relates to a new process of synthesis of an antihypertensive agent, N-pentanoyl-N-[[2'-(1H-tetrazole-5-yl)[1,1'-biphenyl]-4-yl]methyl]-L-valine (1), also known under the generic name of valsartan, by selective reaction of N-pentanoyl-N-[[2'-(1H-tetrazole-5-yl) [1,1'-biphenyl]-4-yl]methyl]-L-valine methyl-ester (14) with metallic or quaternary ammonium trialkylsilanolates by SN2 reaction. The compound 14 was produced in four reaction steps starting from 2N-trityl-5-(4'-methylbiphenyl-2-yl)tetrazole (17) and L-valine methyl-ester (11). Free-radical bromination of the compound 17 with N-bromosuccinimide produced 2N-trityl-5-(4'-bromomethylbiphenyl-2-yl)tetrazole (7), which in the reaction with L-valine methyl-ester (11) results in N-[[2'-(2N-trityl-tetrazole-5-yl)[1,1'-biphenyl]-4­yl]methyl]-L-valine methyl-ester hydrobromide (15). Acylation of the compound 15 with pentanoyl chloride in the presence of trialkylamine bases results in N-pentanoyl-N-[[2'-(2N­trityl-tetrazole-5-yl)[1,1'-biphenyl] -4-yl]methyl]-L-valine methyl-ester (16). Removal of trityl protecting group by strong acids produces the key intermediary, compound 14.