Based on the success of diacyl-tert-butylhydrazines RH-5849 and RH-1266 in controlling agricultural crop pests, we endeavored to synthesize our own diacylbenzyl- and arylhydrazine derivatives for use against the malaria vector Anopheles gambiae. In the process of producing a library of compounds for assay against An. gambiae, it became clear that employing regioselective acylation techniques (in molecules that feature two nucleophilic, acyclic nitrogen atoms α to one another) would be imperative. Synthesis of the library derivatives proceeded rapidly and after topical assay, we found three compounds that were more toxic than the RH-series leads. One of the three displayed an LD50 value of half that of RH-1266, though patch clamp assay concluded that toxicity was not necessarily linked to inhibition of mosquito K+ channel Kv2.1. The acylation of monoarylhydrazines appears simple, but its regioselectivity is poorly understood when assumed as a function of basicity correlating to nucleophilic strength. We determined the ratio of the rate constants for distal to proximal N-acylation using 19F NMR spectroscopic analysis of reactions of 4-fluorophenylhydrazine with limiting (0.2 equiv) acylating agent in the presence of various bases. Acid anhydrides gave consistent preference for distal acylation. The selectivity of acylation by acyl chlorides when using pyridine gives strong distal preference, whereas use of triethylamine or aqueous base in conjunction with aroyl chlorides showed a moderate preference for proximal acylation. This observation yielded a convenient one-step method to synthesize proximal aroylarylhydrazines in yields comparable or superior to that provided by the standard three-step literature approach. Combined with NMR evidence of the distal nitrogen as the unambigiously stronger base of the two nitrogens, we propose a single electron transfer mechanism that predicts the regiochemistry of arylhydrazines toward acylating agents better than the nucleophilicity model based on pKa values. While synthesizing the acylhydrazine library for assay against An. gambiae, NMR spectroscopy revealed rotational isomerisms of two types: chiral helicity (M)/(P) and acyl (E)/(Z)-isomerism due to hindered rotation. Variable temperature NMR allowed the measurement of N-N bond rotational barriers, as well as estimate the barrier of (E)/(Z) interconversion. We obtained the X-ray crystal structures of four diacylhydrazines to test this hypothesis and revealed both the twist conformation around the N-N bond axis and (E)/(Z)-isomerism around the proximal acyl group. Computation (which agreed with the crystal structures) allowed us to estimate which (E)/(Z)-isomers were most likely being observed in solution at room temperature by NMR spectroscopy. In addition, we were able to calculate transition structures corresponding to N-N bond rotational barriers of (E,Z)- and (Z,Z)-isomers of model molecules and rationalize the difference in coalescence temperatures between (E,Z)- and (Z,Z)-isomers. / Ph. D.

Le rhinovirus (RV) est connu pour être l'étiologie de plus de la moitié des rhumes bénins. Ces virus ont également été associés à des pathologies respiratoires beaucoup plus graves (asthme, bronchopneumopathie chronique obstructive (BPCO) et mucoviscidose). Le développement d'inhibiteurs de décapsidation du virus, appelés agents « capsid-binders », est ainsi devenu une priorité pour de nombreux laboratoires de recherche. Dans ce contexte, une classe d’inhibiteurs se liant au sein de la poche hydrophobe de la protéine capsidaire VP1 a été développée par notre équipe au travers d’une stratégie radicalaire médiée par le TDAE (Tétrakis(DiméthylAmino)Ethylène). Dans le but de poursuivre les investigations sur le hit LPCRW_0005, un travail de pharmacochimie a été entrepris selon deux approches. Dans un premier temps, une optimisation de la taille du LPCRW_0005 a été envisagée par un allongement du squelette chimique. La conception de ces molécules a été guidée par l’utilisation de modélisation moléculaire via la réalisation de docking rigide ligand/protéine. La synthèse de nombreux composés et leur évaluation in vitro, ont permis de mieux apprécier le potentiel biologique de ce type de dérivés. L’identification de la configuration active du centre stéréogène porté par le linker alcool a été rendue possible par la séparation énantiosélective de certains inhibiteurs suivie d’une caractérisation basée sur un protocole de Mosher. Dans un second temps, une étude comparative des séquences primaires protéiques, nous ont conduits à concevoir de nouveaux composés afin de développer des « capsid-binders » à plus large spectre d'action. / Rhinovirus (RV), virus of Picornaviridae family, is known to be the aetiology of more than half of the common cold. Through advances in molecular biology, the rhinoviruses have been associated with much more serious respiratory pathologies (asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis). So, the development of viral attachment and/or uncoating inhibitors named « capsid-binders » molecules has become a priority for many research laboratories. In this context, a class of inhibitors binding into a hydrophobic pocket of the VP1 capsid protein has been identified by our team through a TDAE strategy. In order to follow the investigations on the LPCRW_0005 hit, a pharmacochemistry work was begun according to two approaches. Initially, an optimisation of the LPCRW_0005 size was envisaged by an extension of the scaffold via various pallado-catalyzed cross-coupling reactions. The design of these molecules was guided by the use of molecular modeling via a rigid ligand/protein docking. The synthesis of many compounds and their in vitro biological evaluation on HeLa cells infected with the rhinovirus 14 (RV-B14), refined our knowledge about the biological potential of such a scaffold. The enantioselective separation of some inhibitors followed by a Mosher’s protocol allowed us to identify the active configuration of the alcohol linker. Finally, a comparative study of protein primary sequences as well as drug design, led us to design and develop more potent broad-spectrum capsid-binders.

Ce travail de pharmacochimie est consacré à la synthèse de nouvelles molécules benzéniques en vue d’étudier leurs propriétés pharmacologiques in vitro sur le Rhinovirus humain 14 mais également d’en déduire des relations de structure activité. En effet, le fil conducteur du projet de thèse est un travail de pharmacomodulation en collaboration avec le Rega Institute for Medical Research de Louvain. La méthode principale de synthèse de ces structures est basée sur la méthodologie TDAE ou Tétrakis(DiméthylAmino)Ethylène, appliquée sur des substrats dérivés du chlorure de nitrobenzyle. La synthèse et l’évaluation biologique de plus de 100 molécules a permis de décrire 5 hits dérivés du 4,5-diméthoxybenzène présentant des activités biologiques intéressantes in vitro (Concentration Effective Médiane de 1,5 à 4,3 μM ; index de sélectivité de 6 à 92). Les différentes stratégies adoptées lors de ce travail de pharmacochimie ont permis d’étendre l’étude des réactions par transfert monoélectronique sur de nouveaux substrats. Ainsi, le 1-(3-chloroprop-1-ynyl)-4-nitrobenzène a fait l’objet d’une étude en méthodologie LD-SRN1 avec des nitroalcanes, nitrocycloalcanes ainsi qu’avec des anions sulfinates ; ces travaux ont permis de décrire de nouveaux substrats insaturés originaux avec de bons rendements. De plus, la réactivité de ce substrat original a été évaluée en méthodologie TDAE avec des aldéhydes aromatiques. Ces travaux ont été valorisés par la synthèse de diarylbutynols originaux et ouvrent de nombreuses perspectives de recherche sur ce même noyau. / This pharmacochemistry work aims at synthesizing of new benzenic derivatives molecules with the scope to study both the chemical and antirhinoviruses 14 pharmacological properties in vitro. In fact, this work was focused on the pharmacomodulation of benzonitrile derivatives in collaboration with Rega Institute for Medical Research group. One hundred structural analogues were synthesized and a structure-activity-relationship was established. Biological assays showed five molecules with interesting anti-hRV 14 activities (EC50 from 1.5 to 4.3 and selectivity index from 6 to 92).These products derived from the TDAE-initiated reaction of various nitrobenzyl chloride analogues. Different strategies directed toward this pharmacochemistry project permitted to study single electron transfer (SET) reaction on original substrates. In this way, we explored the concept of LD-SRN1 on a propargylic chloride derivative such as 1-(3-chloroprop-1-ynyl)-4-nitrobenzene with nitronate and sulfinate anions. This latter compound also constitutes a potential substrate for the preparation of a propargylic anion using the TDAE strategy. So, we examined the use of TDAE methodology in alkyne series with various aromatic aldehydes in the presence of TDAE. These last works opened the scope of single electron transfer (SET) reactions.