Kinetic target-guided synthesis (TGS) and in situ click chemistry are among unconventional discovery strategies having the potential to streamline the development of protein-protein interaction modulators (PPIMs). In kinetic TGS and in situ click chemistry, the target is directly involved in the assembly of its own potent, bidentate ligand from a pool of reactive fragments. Herein, we report the use and validation of kinetic TGS based on the sulfo-click reaction between thio acids and sulfonyl azides as a screening and synthesis platform for the identification of high-quality PPIMs. Starting from a randomly designed library consisting of nine thio acids and nine sulfonyl azides leading to eighty one potential acylsulfonamides, the target protein, Bcl-XL selectively assembled four PPIMs, acylsulfonamides SZ4TA2, SZ7TA2, SZ9TA1, and SZ9TA5, which have been shown to modulate Bcl-XL/BH3 interactions. To further investigate the Bcl-XL templation effect, control experiments were carried out using two mutants of Bcl-XL. In one mutant, phenylalanine Phe131 and aspartic acid Asp133, which are critical for the BH3 domain binding, have been substituted by alanines, while arginine Arg139, a residue identified to play a crucial role in the binding of ABT-737, a BH3 mimetic, has been replaced by an alanine in the other mutant. Incubation of these mutants with the reactive fragments and subsequent LC/MS-SIM analysis confirmed that these building block combinations yield the corresponding acylsulfonamides at the BH3 binding site, the actual "hot spot" of Bcl-XL. These results validate kinetic TGS using the sulfo-click reaction as a valuable tool for the straightforward identification of high-quality PPIMs. Protein-protein interactions of the Bcl-2 family have been extensively investigated and the anti-apoptotic proteins (Bcl-2, Bcl-XL, and Mcl-1) have been validated as crucial targets for the discovery of potential anti-cancer agents. At the outset, Bcl-2 and Bcl-XL were considered to play an important role in the regulation of apoptosis. Accordingly, several small molecule inhibitors targeting Bcl-2 and/or Bcl-XL proteins were primarily designed. A series of acylsulfonamides targeting these proteins were reported by Abbott laboratories, ABT-737 and ABT-263 being the most potent candidates. Remarkably, these molecules were found to exhibit weaker binding affinities against Mcl-1, another anti-apoptotic protein. Further experimental evidence suggests that, inhibitors targeting Mcl-1 selectively or in combination with other anti-apoptotic proteins would lead to desired therapeutic effect. As a result, numerous small molecules displaying activity against Mcl-1 have been identified so far. Specifically, acylsulfonamides derived from structure activity relationship by interligand nuclear overhauser effect (SAR by ILOEs), a fragment-based approach, have been recently reported with binding affinities in the nanomolar range. In the meantime, we have reported that the kinetic TGS approach can also be applied to identify acylsulfonamides as PPIMs targeting Bcl-XL. Taken together, structurally novel acylsulfonamides can be potentially discovered as Mcl-1 inhibitors using the kinetic TGS approach. Thus, a library of thirty one sulfonyl azides and ten thio acids providing three hundred and ten potential products was screened against Mcl-1 and the kinetic TGS hits were identified. Subsequently, control experiments involving Bim BH3 peptide were conducted to confirm that the fragments are assembled at the binding site of the protein. The kinetic TGS hits were then synthesized and subjected to the fluorescence polarization assay. Gratifyingly, activities in single digit micromolar range were detected, demonstrating that the sulfo-click kinetic TGS approach can also be used for screening and identification of acylsulfonamides as PPIMs targeting Mcl-1. The amide bond serves as one of nature's most fundamental functional group and is observed in a large number of organic and biological molecules. Traditionally, the amide functionality is introduced in a molecule through coupling of an amine and an activated carboxylic acid. Recently, various alternative methods have been reported wherein, the aldehydes or alcohols are oxidized using transition metal catalysts and are treated with amines to transform into the corresponding amides. These transformations however, require specially designed catalysts, long reaction times and high temperatures. We herein describe a practical and efficient amidation reaction involving aromatic aldehydes and various azides under mild basic conditions. A broad spectrum of functional groups was tolerated, demonstrating the scope of the reaction. Consequently, the amides were synthesized in moderate to excellent yields, presenting an attractive alternative to the currently available synthetic methods.

Hyaluronic acid (HA) is a naturally occurring polymer that holds considerable promise for tissue engineering applications. Current cross-linking chemistries often require a coupling agent, catalyst, or photoinitiator, which may be cytotoxic, or involve a multistep synthesis of functionalized-HA, increasing the complexity of the system. With the goal of designing a simpler one-step , aqueous-based cross-linking system, we synthesized HA hydrogels via Diels-Alder “click” chemistry. Furan-modified HA derivates were synthesized and cross-linked via dimaleimide poly(ethylene glycol). By controlling the furan to maleimide molar ratio, both the mechanical and degradation properties of the resulting Diels-Alder cross-linked hydrogels can be tuned. Rheological and degradation studies demonstrate that the Diels-Alder click reaction is a suitable cross-linking method for HA. These HA cross-linked hydrogels were shown to be cytocompatible and may represent a promising material for soft tissue engineering.

Hyaluronic acid (HA) is a naturally occurring polymer that holds considerable promise for tissue engineering applications. Current cross-linking chemistries often require a coupling agent, catalyst, or photoinitiator, which may be cytotoxic, or involve a multistep synthesis of functionalized-HA, increasing the complexity of the system. With the goal of designing a simpler one-step , aqueous-based cross-linking system, we synthesized HA hydrogels via Diels-Alder “click” chemistry. Furan-modified HA derivates were synthesized and cross-linked via dimaleimide poly(ethylene glycol). By controlling the furan to maleimide molar ratio, both the mechanical and degradation properties of the resulting Diels-Alder cross-linked hydrogels can be tuned. Rheological and degradation studies demonstrate that the Diels-Alder click reaction is a suitable cross-linking method for HA. These HA cross-linked hydrogels were shown to be cytocompatible and may represent a promising material for soft tissue engineering.

La thèse porte sur le développement de stratégies non conventionnelles de peptides contraints et la modulation des structures secondaires pour augmenter la reconnaissance biologique de ces peptides.Les peptides jouent un rôle important dans de nombreux processus et sont donc d'un intérêt grandissant pour l'industrie pharmaceutique. Cependant, leur utilisation comme médicament reste limitée à cause de leur flexibilité conformationnelle, leur sensibilité aux protéases et leur faible biodisponibilité et pharmacodynamie. Dans ce contexte, la caractérisation des interactions ligands-récepteurs est cruciale pour comprendre les processus de reconnaissance et le design d'agonistes sélectifs, potentiels nouveaux médicaments. Ainsi, le développement d'outils portant des modifications structurales présente un intérêt grandissant pour trouver de nouveaux médicaments. Ces changements structuraux permettent d'affiner les conformations privilégiées et donc de comprendre la spécificité d'interactions par rapport à des sous-types de récepteurs ayant des propriétés physicochimiques et pharmacologiques particulières.Dans la première partie de ce travail, une stratégie optimisée pour la synthèse de fragments N-terminaux (1-34) de la séquence PTHrP.PTHrP(1-34)NH2 est décrite : H-Ala1-Val-Ser-Glu-His-Gln-Leu-Leu-His-Asp10-Lys-Gly-Lys-Ser-Ile-Gln-Asp-Leu-Arg-Arg20-Arg-Phe-Phe-Leu-His-His-Leu-Ile-Ala-Glu30-Ile-His-Thr-Ala-NH2. D'un point de vue synthètique, la formation de clusters dus à la présence de plusieurs résidus arginine, l'encombrement stérique, la longueur de la séquence et la présence de résidus hydrophobes dans la partie 19-28 du PTHrP rendent la synthèse difficile et donnent un enjeu important à la synthèse. C'est pourquoi, nous avons focalisé nos efforts sur l'optimisation du protocole opératoire. En particulier, nous avons montré l'intérêt d'utiliser une activation sous microondes pour la synthèse, avantages en termes de rendement et de pureté du peptide. La synthèse de PTHrP(1-34) a été optimisée à la fois sous activation par la temperature et sous microondes dans des conditions identiques. Les micoondes ont aussi été utilisé pour la synthèse de PTHrP(1-34)NH2. L'élongation de la chaine peptidique a été suivie par l'analyse UPLC-ESI-MS des fragments obtenus après micro clivage assisté par micro ondes. Cette stratégie nopus a permis , à travers la caractérisation des séquences délétées, d'identifier les points critiques de la synthèse, nécessitant les microondes. Dans la seconde partie de la thèse, ont été entreprises le design et la synthèse d'une série de cyclopeptides (i-to-i+5) 1,4- et 4,1-disubstitués pontés par un triazole, analogues de MTII. MTII, Ac-Nle4-c[Asp5-D-Phe7-Lys10]αMSH4-10-NH2 est un super agoniste agissant d'une manière non sélective des récepteurs de la mélanocortine MC1R, MC3R, MC4s, et MC5s. Ce peptide est caractérisé par un lien lactame entre les résidus Asp5 et Lys 10 stabilisant une structure β-turn, cruciale pour l'activité.Cependant MTII n'est pas sélectif des différents sous-type des récepteurs de la mélanocortine. L'importance particulière du système mélanocortine souligne le besoin de trouvé des analogues plus sélectifs, présentant une meilleure pharmacocinétique et une meilleure biodisponibilité. L'introduction du triazole [1,2,3] utilise dans nos analogues vise à stabiliser une conformation , à la place du lien lactame de MTII. La diversité est apportée par une variation de la position du triazole de i à i+5. Il est obtenu par une cycloaddition alcyne/azoture catalysée par le Cu(I) (CuAAC), générant très sélectivement l'adduit 1,4. Les analogues clickés de MTII présentant une position différente du triazole ont été synthétisé en phase solide et en solution. Les études conformationnelles et biologiques ont été conduites pour identifier l'analogue présentant la meilleure conformation β-turn conduisant à la meilleure activité biologique.

Substituted tetrazines have been found to undergo facile inversed electron demand Diels-Alder reactions with “tunable” reaction rates. By varying the substituents on tetrazine, cycloaddition rate variations of over 200 fold have been achieved with the same dienophile. Coupled with the availability of different dienophiles, such as norbornene, the reaction rate difference can be over 14,000 folds. These substituted tetrazines can be very useful for selective labeling under different conditions. This finding paves the way to utilize tetrazine conjugation reactions for not only DNA but also stage labeling work. Carbon monoxide (CO) belongs to the gasotransmitter family of signalling molecules in the mammalian systems with importance on par with that of NO and H2S. Studies have shown that endogenous production of CO has anti-inflammatory, anti-proliferative, and anti-apoptotic effects in mammalian system. Besides of the conventional metal-based carbon monoxide releasing molecules (CORMs) to deliver CO for therapeutic purposes, organic CO prodrugs represent a new direction. Here we report the “click and release” approached to release CO. Unlike the metal-based CORMs, our system does not contain transition metal and liberates CO with controllable manner and possesses potential tunable releasing rate property under physiological conditions.

The synthesis of well-defined polymer nanoparticles will have immediate applications in the biomedical industry as nanocontainers for the controlled delivery and release of water insoluble drugs. The ability to control molecular weight, particle morphology and chemical functionality and to obtain polymeric nanoparticles with narrow molecular weight and particle size distributions is paramount for their application-specific design. Two synthetic approaches were investigated in the synthesis of well-defined polymer nanoparticles, emulsion polymerization and self assembly. The successful implementation of Reversible Addition-Fragmentation Chain Transfer (RAFT) in emulsion polymerization was the first challenge faced when controlling nanoparticle molecular weight and size. Initially we showed that successful ‘living’ emulsion polymerizations of styrene could be carried out using a non-ionic surfactant. The success was achieved when preparing polymers of low molecular weight (5 and 9 K targeted Mn’s with polydispersities (PDIs) below 1.2). Deviation from ideal ‘living’ behavior occurred when targeting Mn’s greater than 20 K (at 100 % conversion). The ‘degassing technique’ was then investigated as an avenue to generate stable polystyrene nanoparticles by emulsion polymerization without the addition of surfactant (residual surfactant can result in detrimental effects on product quality). The polymerization of this emulsion system in the presence of a low reactive RAFT agent was ‘living’ in nature. In the presence of a high reactive RAFT agent the emulsion system showed ‘living’ nature, however, secondary nucleation occurred, which resulted in broad molecular weight distribution (MWD). Thus, the emulsion polymerization approach to preparing well-defined polymer nanoparticles was giving less than desirable results. An alternative method to prepare polymer nanoparticles with controlled chemical composition and morphology is to self assemble pre-synthesized block copolymers in water. This approach has several significant advantages over the emulsion systems: (i) all polymer chains are of near uniform chain length and chemical composition, (ii) the ratio between the hydrophobic and hydrophilic polymers can easily be controlled, (iii) chemical functionality can be located in different morphological regions, (iv) a wide range of 3-dimensional structures apart from spheres can be prepared (i.e. rods and vesicles), and (v) additives such as surfactant, stabilizers and residual monomer usually found after an emulsion polymerization are not required in the self assembly methodology. These advantages justify our shift in strategy. The only disadvantage of the self assembly process is that one cannot reach high weight fractions of polymer in water and is usually limited to below 2 wt-%, where as emulsion polymerizations can allow weight fractions of polymer close to 50 wt-%. Well-defined amphiphilic 4-arm star polyacrylic acid-block-polystyrene (PAA-b-PSTY) copolymers, prepared by RAFT solution polymerization, were dispersed in water to form core-shell micelles, in which the shell consisted of tethered PAA loops. The entropic penalty for having such loops resulted in a less densely packed PSTY core when compared to linear diblock copolymers of the same arm length. The surface of the shell was irregular due to the tethering points, but when cleaved the PAA chains extended to form a regular and relatively uniform corona. Controlling the polymer architecture enabled the synthesis of polymer micelles with tethered PAA loops, which could be opened to form uniform corona when desired. Three-miktoarm star and dendrimers with miktoarms consisting of PSTY, polytert-butyl acrylate (PtBA), polymethyl acrylate (PMA) and PAA were then synthesized using a combination of Atom Transfer Radical Polymerization (ATRP) and Huisgen 1,3-dipolar cycloaddition ‘click’ reactions. In all reactions, the stars and dendrimers were well-defined with PDIs lower than 1.09. This was the first step in the synthesis of well-defined highly ordered polymer structures. The synthesis of such structures demands high level of purity at each synthetic step eliminating the possibility of side reactions, which as of consequence lowers product yields. The synthesis and use of reactive solid supports to remove excess linear polymer to increase the yields of polymeric 3-arm stars and dendrimers was employed. These supports are a cheap approach to scavenge polymeric species with either azido or alkynyl functionality, after which the solid support can be filtered away from the product. These supports aided the synthesis of 3rd generation polymeric dendrons and dendrimers consisting of homopolymer PSTY with either solketals or alcohols at the periphery, diblock PSTY and PtBA, and amphiphilic diblock. The methodology used to construct these structures was a combination of ATRP to produce linear polymers with telechelic functionality, with the subsequent use of this functionality to join the polymers together via ‘click’ reactions. Micellization of the amphiphilic structures in water produced polymer nanoparticles of uniform size. The dendrimer nanoparticles were 18 nm in diameter, consisting of 19 individual dendrimers. The dendrimers most probably have no mutual interpenetration and thus pack uniformly to form the micelles. The dendron nanoparticles were 21 nm with an aggregation number of 43 dendrons per micelle, which suggests they form cone-like structures and self-assemble to form crew-cut micelles. Using a convergent approach polymer structures with unprecedented chemical diversity (hydrophobic or amphiphilic) and complexity (G2 miktoarm dendrimers with a degradable core) consisting of PSTY, PMA, PtBA and PAA were then synthesized with high purity using copper wire as the ‘click’ catalyst.

Les glioblastomes sont des tumeurs cérébrales qui sont extrêmement agressives, et qui, en dépit de l'arsenal thérapeutique (chirurgie, radiothérapie ou chimiothérapie), ne laissent pas plus de 16 mois d'espérance de vie aux patients. Dans le cadre de cette thèse, nous proposons d'utiliser certaines toxines en tant que vecteurs pour l'administration de médicaments anticancéreux, et notamment pour le traitement du gliome. Les travaux présentés ici se concentrent sur l’utilisation de variants de la maurocalcine (MCa) et des analogues de la chlorotoxine (CTX). La MCa est une toxine issue du venin du scorpion Scorpio maurus palmatus, qui est capable de pénétrer dans les cellules facilement et rapidement. Il a été prouvé que la MCa peut entrer dans la cellule avec une cargaison. C’est en exploitant cette capacité présente chez deux de ces variants que nous avons synthétisé avec succès deux nouveaux composés à base de cette toxine avec de la doxorubicine et un dérivé du platine. Les études de toxicité et de caractérisation de ces composés qui ont été réalisé on permit de mettre en évidence l’intérêt et le potentiel de la MCa. La seconde partie de ces travaux de thèse portée sur la CTX et des peptides semblables, également extrait de venin de scorpion. Ils ont la particularité de fixer / interagir uniquement avec les cellules cancéreuses d'origine gliale. Après une rapide caractérisation de ces analogues de la CTX, l’un d’eux la Lqh-8/6 a été utilisé avec succès pour l'administration ciblée de doxorubicine. L’ensemble des travaux menés durant cette thèse constitue une base de départ solide pour une amélioration des systèmes de vectorisation, surtout en cancérologie de molécules actives. De plus ces résultats mettent aussi en avant l’avantage de l’utilisation d’un système de couplage « universel » basé sur la chimie click. / Glioblastoma are cerebral tumors that are extremely aggressive, and that, in spite of a battery of therapeutic interventions (surgery, radiotherapy or chemotherapy), leave no more than 16 months life expectancy to the patients. As part of this thesis, we propose to use some selected toxins as vectors for the delivery of anticancer drugs, and namely for the treatment of glioma. The works presented here concentrate on the use of variants of maurocalcine (MCa) and the analogues of chlorotoxine (CTX). MCa is a toxin from of the scorpion Maurus palmatus that has cell penetrating propriety. It has been proved that MCa can enter the cell with cargoes. While exploiting this present capacity to two of these variants we synthesized successfully two new compounds with this toxin with the doxorubicine and a by-product of the platinum. Toxicity studies and characterization of these compounds that have been made were permitted to highlight the interest and potential of the MCa. The second part of the thesis work focused on the CTX and similar peptides, also extracted from scorpion venom. They have the particularity to fix/ interact only with cancer cell from neuroectodermal origin. After a fast characterization of these analogues of CTX, one of them (Lqh-8/6) was successfully used for the targeted administration of doxorubicin. All work conducted during this thesis constitutes a solid starting point for an improvement of the systems of vectorization of active molecules, especially in cancer research Moreover, these results also emphasize the advantage of the use of a system of "universal" coupling based on the click chemistry.

Des nanocapsules (NCs) biodégradables contenant une substance active et destinées à des applications environnementales ont été élaborées par un procédé d’émulsion-évaporation de solvant couplé à une réaction de chimie « click » interfaciale. Deux types de réactions « click » ont été testés: (i) cycloaddition azide-alcyne catalysée par le Cu(I) et (ii) thiol-ène. Ces NCs sont constituées d’une écorce en polymère hydrophobe (polylactide) entourant un cœur liquide (Miglyol®810) et recouverte d’une couronne hydrophile polysaccharide (dextrane). Des nanosphères (sans cœur liquide) ont aussi été produites. Ces nano-objets ont été caractérisés en termes de distribution de tailles, morphologie, taux et épaisseur de recouvrement en dextrane ainsi qu’efficacité de couplage « click ». La stabilité colloïdale en milieu salin et la stabilité du recouvrement en présence d’un tensioactif compétitif ont été étudiées. Enfin, une substance active a été encapsulée et libérée à partir des nano-objets / Biodegradable nanocapsules allowing encapsulation of active substances for environmental applications were produced by emulsion-evaporation method combined with a “click” reaction occurring at the liquid/liquid interface of emulsion droplets. Two types of “click” reaction were tested: (i) copper-catalyzed azide-alkyne cycloaddition (CuAAC) and (ii) thiol-ene reaction. The NCs are composed of a hydrophobic polymer shell (polylactide), a liquid core (Miglyol®810) and a hydrophilic polysaccharide coating (dextran). For comparison, nanospheres (without oily core) were also prepared. These nano-objects were characterized in terms of size distribution, dextran coverage density and thickness, “click” coupling efficiency and morphology. Colloidal stability in NaCl solutions as well as dextran coverage stability against an anionic competitive surfactant were also studied. Finally, an active substance was encapsulated and released from these nano-objects

As cumarinas são estruturas interessantes aos olhos da química medicinal, apresentando diversas atividades biológicas sobre os mais variados alvos. Neste trabalho, em um primeiro momento, realizamos a extração com CO2 em meio supercrítico das cumarinas de Pterocaulon balansae, planta nativa do Rio Grande do Sul que apresenta em sua composição grandes quantidades destes compostos. A extração com CO2 supercrítico apresentou rendimentos satisfatórios em massa de sete cumarinas previamente descritas para estas espécies. Dentre estes se destacam os compostos majoritários 7-(2,3-epoxi-3-metil-3-butiloxi)-6-metoxicumarina e 5,6-dimetoxi-7-(2’,3’-epoxi-3-metilbutiloxi) cumarina. Realizamos também a síntese de 4-metilcumarinas através de reação de Pechmann, obtendo o composto LaSOM 77 (7-hidroxi-4-matilcumarina) com excelentes rendimentos, onde realizamos uma diversificação estrutural através da adição de um linker e posteriormente a síntese de triazóis através de “Click Chemistry”. Para tanto, utilizamos uma biblioteca de 35 alcinos disponíveis comercialmente e outros 3 sintetizados em nosso laboratório. Sendo assim, obtivemos uma biblioteca de 38 híbridos cumarina-triazol que apresentaram excelentes rendimentos, em tempos reacionais que variaram entre 20 e 50 minutos de reação sob irradiação de microondas. Os testes biológicos preliminares frente a linhagens cancerígenas indicaram que os compostos sintetizados apresentam potencial utilização como anticancerígenos, sendo ativos frente a linhagens celulares de câncer de pulmão, fígado e mama, apresentando baixa toxicidade em células sadias. A partir das investigações teóricas e experimentais relacionadas à este trabalho foi produzido um artigo de revisão, intitulado “New insights into the chemistry and antioxidante activity of coumarins” está aceito pelo periódico Current Topics in Medicinal Chemistry. / Coumarins are interesting structures for the medicinal chemistry, because present several biological activities. At first, we performed the supercritical CO2 extraction from Pterocaulon balansae, a plant native from Rio Grande do Sul, which has in its composition large amounts of these compounds. The extraction with supercritical CO2 showed satisfactory yields of seven coumarins previously described for this species. Among these compounds the coumarins 7-(2,3-epoxy-3-methyl-3-butyloxy)-6-methoxycoumarin e 5,6-dimethoxy-7-(2’,3’-epoxy-3-methylbutyloxy) coumarin are the majority compunds. We also performed the synthesis of 4-methylcoumarins using Pechmann reaction, obtaining the compound LaSOM 77 (7-hydroxy-4-methyl-coumarin) in excellent yield and perfomed the structural diversification trougth the addition of a linker and subsequentely synthesis of 1,2,3-triazoles by Click Chemistry. Therefore, was used a colection of 35 commercialy available alkynes and other 3 synthesized in our laboratory to obtain a colection of 38 coumarin-triazole hybrids in excellent yields and time of reaction ranging betwenn 20 and 50 minutes under microwave radiation. Preliminary biological tests against cancerous strains indicated that the synthesized compounds have potential use as anticancer agents against cell lines of lung, liver and breast cancer. From the theorical and experimental data from this work, one review paper was produced: The article is intitled “New insights into the chemistry and antioxidante activity of coumarins” is accepted to the journal "Current Topics in Medicinal Chemistry".

Made available in DSpace on 2016-06-02T20:34:57Z (GMT). No. of bitstreams: 1 6269.pdf: 8614736 bytes, checksum: a96a25f33487faa72f57cbe4d7b8e01b (MD5) Previous issue date: 2014-08-29 / Universidade Federal de Sao Carlos / The studies presented herein show the use of molecular modelling coupled to spectroscopic data to tackle four different problems in organic chemistry. In the first study, the sulfonylation of the primary hydroxyl group of the compound (2R,3S,6S)-2-(hydroxymethyl)-6-(1-phenyl-1H-1,2,3-triazol-4-yl)-3,6-dihydro-2Hpyran- 3-ol was addressed. The results show that the occurrence of the reaction depends on the stability of the S Cl secondary interactions and of the C-H Cl hydrogen bonds along the reaction pathway. The second investigation was the cycloaddition between benzyl azide and (organotelanil) alkynes. This reaction has a high driving force towards the products and generates fast and selectively a triazole with a n-butyltelluride substituent attached at position 5, which is stabilized by CH...Te interactions. So this cycloaddition fits the requirements of Click Chemistry. In third place, the conformations and relative configurations of 7 and 9 membered rings were elucidated by evaluating steric strain. The 7 membered ring shows a twisted chair conformation (TC) with C1, C7 and C10 having relative configurations S, R and S. The 9 membered ring has a twisted chair-chair conformation (TCC) and relative configurations R, S of C7 and C10. The fourth study was the optimization of rotational conformations of 1- (arylsulfonyl)indole derivatives. The different optimized conformations have the same stability and low rotational energy barrier, so that in the solid state the number of independent molecules in the asymmetric unit essentially depends on the packing intermolecular interactions. Regarding the stability of sulfonamide bonds the importance of hyperconjugative effects were showed, and the origin of the rotational barrier in the S-N bond is explained by the difference in steric hindrance and electrostatic interactions in the transition and the fundamental states. / As pesquisas aqui apresentadas mostram o uso da modelagem molecular acoplada a dados espectroscópicos em quatro problemas diferentes de química orgânica. No primeiro estudo abordou-se a sulfonilação da hidroxila primária do composto (2R,3S,6S)-2-(hidroximetil)-6-(1-fenil-1H-1,2,3-triazol-4- il)-3,6-dihidro-2H-piran-3-ol. Os resultados mostram que a ocorrência da reação depende da estabilidade de interações secundárias S...Cl e de ligações de hidrogênio C-H...Cl ao longo do caminho reacional. O segundo sistema investigado foi a cicloadição entre a benzil azida e (organotelanil)alcinos. Essa reação possui elevada driving force na direção dos produtos e gera seletiva e rapidamente o triazol com o substituinte n-butiltelureto ligado na posição 5, o qual é estabilizado por interações C-H...Te. De modo que essa cicloadição ajusta-se aos requisitos da proposta Click Chemistry. No terceiro trabalho, as conformações e configurações relativas de anéis de 7 e 9 membros foram elucidadas avaliando tensões estéricas. O anel de 7 membros apresenta a conformação cadeira torcida (TC) e configuração relativa S,R,S para C1, C7 e C10. Já o de 9 membros possui conformação cadeira-cadeira torcida (TCC) e configuração relativa R, S para C7 e C10. O quarto problema abordado foi a otimização de conformações rotacionais de derivados de 1-(arilsulfonil)indol. As diferentes conformações otimizadas possuem a mesma estabilidade e baixa barreira energética rotacional, de forma que no estado sólido o número de moléculas independentes na unidade assimétrica depende essencialmente das interações intermoleculares no empacotamento. Com relação à estabilidade das ligações sulfonamidas mostrou-se a importância dos efeitos hiperconjugativos, e a origem da barreira rotacional na ligação S-N é explicada pela diferença nos impedimentos estéricos e interações eletrostáticas entre os estados de transição e o fundamental.