Synthesis and antifungal activity of 2-chloromethyl-1H-benzimidazole derivatives against phytopathogenic fungi in vitro

A series of 35 benzimidazole derivatives were synthesized from 2-chloromethyl-1H-benzimidazole in good yields. Their structures were characterized by (1)H and (13)C NMR and HRESIMS. Antifungal activities of all of the synthesized compounds were evaluated against five phytopathogens fungi (Cytospora sp., Colletotrichum gloeosporioides, Botrytis cinerea, Alternaria solani, and Fusarium solani) using the mycelium growth rate method. Compound 4m displayed strong growth inhibition of C. gloeosporioides, A. solani, and F. solani with IC50 of 20.76, 27.58, and 18.60 μg/mL, respectively. Selective inhibition of B. cinerea instead of the other fungal pathogenes was observed with 7f (IC50 of 13.36 μg/mL), comparable to that of positive control, a commercial agricultural fungicide hymexazol (IC50 of 8.92 μg/mL). Compound 5b exhibited remarkable antifungal properties against Cytospora sp., C. gloeosporioides, B. cinerea, and F. solani with IC50 values of 30.97, 11.38, 57.71, and 40.15 μg/mL, respectively; among the target fungi, 5b was the most active compound and superior to the reference against C. gloeosporioides alone. Structure-activity relationship (SAR) data of these compounds are as follows: (1) introduction of the chlorine atom on para-position in the benzene ring help to increase activity (4f vs 4c; 7f vs 7n), (2) the sulfonyl group is critical for the inhibition of C. gloeosporioides (5b and 5c vs 5a), and (3) the unsubstituted benzene ring improve activity (4m vs 4n, 4e and 4a). Thus, compounds 5b, 4m, and 7f emerged as a new leading structure for the development of new fungicides.

Parallel and automated library synthesis of 2-long alkyl chain benzoazoles and azole[4,5-b]pyridines under microwave irradiation

A versatile route to 40-membered library of 2-long alkyl chain substituted benzoazoles (1 and 2) and azole[4,5-b]pyridines (3 and 4) via microwave-assisted combinatorial synthesis was developed. The reactions were carried out in both monomode and multimode microwave oven. With the latter, all reactions were performed in high-throughput experimental settings consisting of an 8 x 5 combinatorial library designed to synthesize 40 compounds. Each step, from the addition of reagents to the recovery of final products, was automated. The microwave-assisted N-long chain alkylation reactions of 2-alkyl-1H-benzimidazole (1) and 2-alkyl-1H-benzimidazole[4,5-b] pyridines (3) were also studied.

Les réactions de transfert monoélectronique : de l’électron au médicament

Electron transfer reactions have been at the heart of great advances in organic and inorganic chemistry and biology since the early work in 1954 by H. Taube (Nobel Chemistry Prize in 1983) and R. Marcus (Nobel Chemistry Prize in 1991). In organic chemistry, a new kind of chain substitution reaction with paramagnetic species was defined and identified as S(RN)1 (substitution, radial-nucleophilic, unimolecular). In our laboratory, choosing more or less complex molecules which possess electron-withdrawing groups and correctly disposed alkylation sites has enabled us to extend this concept to the heterocyclic (S(RN)1 HET) and quinonic (S(RN)1 QUI) series. These studies led us to prepare, under mild operating conditions, highly branched molecules hard to obtain via other pathways and which possess high pharmacological activity in various fields. We have discovered new reaction mechanisms such as LD-S(RN)1 (long-distance S(RN)1) E(RC)1 (elimination radical chain, unimolecular), bis-S(RN)1 and poly-S(RN)1. Moreover, we have developed a new technology using microwaves which increases the interest of electron transfer reactions in medicinal chemistry for drugs synthesis.