Synthesis of new 4′-(N-alkylpyrrol-2-yl)-2,2′: 6′,2″-terpyridines via N-alkylation of a pyrrole moiety

Abstract

New 4′-(N-alkylpyrrol-2-yl)-2,2′:6′,2″-terpyridines were synthesized by N-alkylation of a pyrrole substituent with alkyl halides in dimethyl sulfoxide.

4′-(N-(Propan-1,2-dienyl)pyrrol-2-yl)-2,2′:6′,2″-terpyridine

“…The synthetic approach towards molecule 2 relies on the N-alkylation of the pyrrole moiety of 4 -(pyrrol-2-yl)-2,2 :6 ,2"-terpyridine (3) with propargyl bromide (Figure 2), applying a protocol that has been described for the preparation of N-alkyl terpyridine pyrroles [16]. At the end of the reaction, a single product was noticed by TLC.…”

“…All reagents were purchased from commercial suppliers and used as received. The 4 -(Pyrrol-2-yl)-2,2 :6 ,2"-terpyridine (3) was prepared according to the literature [16]. A volume of 85% Potassium hydroxide pellets (VWR Chemicals, France) was powdered using a mortar and a pestle.…”

4′-(N-(Propargyl)pyrrol-2-yl)-2,2′:6′,2′′-terpyridine

“…A tentative synthesis of 1 through N-propargylation of 4 -(pyrrol-2-yl)-2,2 :6 ,2terpyridine is already reported in the literature [13]. The synthetic pathway that was explored relies on the N-alkylation of the pyrrole ring with propargyl bromide in a strong basic medium [14]. Nevertheless, this approach failed in providing 1, and only isomeric 4 -(N-(propan-1,2-dienyl)pyrrol-2-yl)-2,2 :6 ,2 -terpyridine 2 was obtained (Figure 2).…”

“…explored relies on the N-alkylation of the pyrrole ring with propargyl bromide in a strong basic medium [14]. Nevertheless, this approach failed in providing 1, and only isomeric 4′-(N-(propan-1,2-dienyl)pyrrol-2-yl)-2,2′:6′,2″-terpyridine 2 was obtained (Figure 2).…”

“…Here, the reaction between 2-acetylpyridine and N-propargylpyrrole-2-carboxaldehyde [20] in the presence of potassium hydroxide and aqueous ammonia in ethanol [21] was selected (Figure 3). explored relies on the N-alkylation of the pyrrole ring with propargyl bromide in a strong basic medium [14]. Nevertheless, this approach failed in providing 1, and only isomeric 4′-(N-(propan-1,2-dienyl)pyrrol-2-yl)-2,2′:6′,2″-terpyridine 2 was obtained (Figure 2).…”