Synthesis of C,N'-linked bis-heterocycles using a deprotometalation-iodination-N-arylation sequence and evaluation of their antiproliferative activity in melanoma cells

Madani Hedidi (1) , Ghenia Bentabed-Ababsa (2) , Aicha Derdour (3) , Thierry Roisnel (1) , Vincent Dorcet (1) , Floris Chevallier (1) , Laurent Picot (4) , Valérie Thiery (4) , Mongin Florence (1)

1 ISCR - Institut des Sciences Chimiques de Rennes
2 Laboratoire de Synthèse Organique Appliquée
3 Laboratoire de Synthèse Organique Appliquée
4 LIENSs - LIttoral ENvironnement et Sociétés

Benzothiophene, benzofuran, benzothiazole and benzoxazole were deprotometalated using the lithium-zinc combination prepared from ZnCl2*TMEDA (TMEDA = N,N,N',N'-tetramethylethylenediamine, 1 equiv) and lithium 2,2,6,6-tetramethylpiperidide (LiTMP, 3 equiv). Subsequent interception of the 2-metalated derivatives using iodine as electrophile led to the iodides in 81, 82, 67 and 42% yields, respectively. These yields are higher (10% more) than those obtained using ZnCl2*TMEDA (0.5 equiv) and LiTMP (1.5 equiv), except in the case of benzoxazole (10% less). The crude iodides were involved in the N-arylation of pyrrole, indole, carbazole, pyrazole, indazole, imidazole and benzimidazole in the presence of Cu (0.2 equiv) and Cs2CO3 (2 equiv), and using acetonitrile as solvent (no other ligand) to provide after 24 h reflux the expected N-arylated azoles in yields ranging from 33 to 81%. Using benzotriazole also led to N-arylation products, but in lower 34, 39, 36 and 6% yields, respectively. A further study with this azole evidenced the impact of 2,2,6,6-tetramethylpiperidine on the N-arylation yields. Most of the C,N'-linked bis-heterocycles thus synthesized (in particular those containing benzimidazole) induced a high growth inhibition of A2058 melanoma cells after a 72 h treatment at 10-5 M.

Keywords: N-arylation; deprotonative metalation; five-membered aromatic heterocycles; melanoma; antiproliferative activity

Domains: Chemical Sciences; Organic chemistry

Madani Hedidi, Ghenia Bentabed-Ababsa, Aicha Derdour, Thierry Roisnel, Vincent Dorcet, et al.. Synthesis of C,N'-linked bis-heterocycles using a deprotometalation-iodination-N-arylation sequence and evaluation of their antiproliferative activity in melanoma cells. Bioorganic and Medicinal Chemistry, 2014, 22 (13), pp.3498-3507. ⟨10.1016/j.bmc.2014.04.028⟩. ⟨hal-00990052⟩