Synthesis of novel vasodilatory active nicotinate esters with amino acid function

A variety of N-(ethyl-4,6-diaryl-3-pyridinecarboxylate)-2-yl]amino acid esters 6a–h were synthesized through the reaction of 2-bromonicotinates 4 with a number of primary amino acid ester hydrochlorides 5 in refluxing tetrahydrofuran in the presence of triethylamine as dehydrohalogenating agent. Similarly, reaction of 4 with N-glycylglycine ethyl ester hydrochloride 7 ‘as a representative example of dipeptide derivative’ afforded smoothly the corresponding N-(ethyl-4,6-diaryl-3-pyridinecarboxylate)-2-yl]-N′-glycylglycine ethyl ester analogues 8. However, reaction of 4 with 5 in refluxing pyridine yielded the unexpected 2-aminonicotinate esters 9. Vasodilation activity screening for the synthesized nicotinate esters was investigated in vitro on the contractile response of vascular thoracic aorta smooth muscle from Wistar rats, where all the tested compounds exhibit considerable vasodilatory properties. In addition, few prepared compounds especially, 6b, 6h and 9b reveal remarkable vasodilation potency (IC₅₀).