Condensation reactions of glycerol with aldehydes and ketones were performed under thermal heating and microwave irradiation regimes. Homogeneous and heterogeneous catalysts were tested in both conditions. A silica sulfated (SiO2-SO3H) heterogeneous catalyst demonstrated the best performance relative to a selectivity of >95% in favor of 5-membered ketals. For acetals, preference in favor of 5-membered or 6-membered functional groups depends on the nature of the catalyst. Homogenous catalysts favor the more stable 6-membered acetals, whereas heterogeneous catalysts favor the less stable 5-membered acetals. However, the isomer ratios in the acetalization reaction are too low, and hence the reaction cannot be used in a synthetic plan for functional materials. Ketalization processes mediated by SiO2-SO3H show a high selectivity in favor of a 5-membered ring (1,3-dioxolane). The scope of condensation was tested with different ketones. A mechanism for heterogeneous catalysis related to the selectivity in the cyclization process is presented herein. Solketal, a commercial product, was also obtained by a condensation reaction of glycerol and propanone, and showed a high selectivity in favor of 1,3-dioxolane. It was transformed to potential allylic and chiral intermediates. A mesogenic core was connected to the organic framework of glycerol to produce a monomer liquid crystal material with a stable smectic-C mesophase.

Microwave synthesis is considered a breakthrough in the field of chemistry due to its benefits over conventional heating methods. We describe, for the first time, the total synthesis of phenytoin adapted for a microwave reactor, proposed as an experiment for undergraduate courses. When carried out with microwaves, the synthetic route provided phenytoin in 6 min and 30 s, while for conventional heating the total time was 170 min. The experiment also involves rapid identification of compounds by TLC, ¹H NMR, FT-IR and melting points determination.

Duas séries de 4-aril-3,4-diidropirimidin-2(1H)-(tio)onas incluindo monastrol (1a), foram sintetizadas por uma metodologia não agressiva ao meio ambiente baseada no uso combinado de ácido cítrico ou ácido oxálico na presença de TEOF (ortoformato de trietila). A atividade como inibidores da proliferação celular da quimioteca de compostos foi avaliada em duas linhagens de gliomas (U138-MG-humana e C6-rato). Os compostos derivados da tiouréia 1f e 1d mostraram atividade citotóxica maior do que a do monastrol. O composto derivado da uréia 2d apresentou a maior atividade citotóxica dentre todos os compostos analisados.

Two series of 4-aryl-3,4-dihydropyrimidin-2(1H)-(thio)ones including monastrol (1a), have been synthesized by an environment-friendly methodology based on the combined use of citric acid or oxalic acid and TEOF (triethylorthoformate). The library was evaluated as inhibitor of cell proliferation on two glioma cell lines (human-U138-MG and Rat-C6). The compounds derived from thiourea 1f and 1d were more cytotoxic than monastrol. The compound derived from urea 2d showed the highest cytotoxic activity among the analyzed compounds.

Neste trabalho nós apresentamos uma revisão sobre a síntese em fase sólida de metabólitos secundários, tais como alcalóides, poliaminas, esteróides, terpenos e flavonóides, descritos na literatura a partir de 2000. Um número considerável de rotas sintéticas elegantes e desafiadoras, usando suportes sólidos, será discutido.

In this manuscript, we disclose solid-phase organic syntheses (SPOS) of small-molecules of some secondary metabolites, such as alkaloids, polyamines, steroids, terpenes, and flavonoids, described in the literature since 2000. A number of elegant, efficient and challenging syntheses on solid support will be presented.

Síntese em fase sólida com auxílio de radiação de microondas do tiazol 2,4-dissubstituído 3 com Resina Merrifield é descrita. As reações envolveram a conversão do grupo hidroxila em amina em cinco etapas - incluindo acoplamento e clivagem - com redimento total de 26% em duas horas de tempo reacional. Todas etapas da rota sintética foram eficientemente monitoradas por FT-IR em discos de KBr, demonstrando que esse método pode ser usado em química combinatória.

Microwave-assisted solid-phase synthesis of the 2,4-disubstituted thiazole 3 on Merrifield Resin is described. The hydroxyl moiety was converted to amine in five steps - including coupling and cleavage - within a total reaction time of 2 hours and 26% overall yield. The entire solid-phase synthesis was efficiently monitored by FT-IR/KBr pellets and allows potential use in combinatorial chemistry.

Solid-phase organic synthesis (SPOS) has been considered the main strategy for the construction of combinatorial libraries, because its simplicity leads to faster synthetic procedures. In addition to that, a series of reports in the specialized literature show great advantages in the use of microwave activation, when compared to classical heating, for instance: shorter reaction times, in some cases from several hours to a few minutes, increase of selectivity and product yields, energy economy and reduction and/or elimination of solvent. This review describes the use of microwave ovens/reactors in solid phase organic synthesis, describing the advantages, equipment and reactions using both techniques.

Síntese em fase sólida com auxílio de radiação de microondas do tiazol 2,4-dissubstituído 3 com Resina Merrifield é descrita. As reações envolveram a conversão do grupo hidroxila em amina em cinco etapas - incluindo acoplamento e clivagem - com redimento total de 26% em duas horas de tempo reacional. Todas etapas da rota sintética foram eficientemente monitoradas por FT-IR em discos de KBr, demonstrando que esse método pode ser usado em química combinatória.

Microwave-assisted solid-phase synthesis of the 2,4-disubstituted thiazole 3 on Merrifield Resin is described. The hydroxyl moiety was converted to amine in five steps - including coupling and cleavage - within a total reaction time of 2 hours and 26% overall yield. The entire solid-phase synthesis was efficiently monitored by FT-IR/KBr pellets and allows potential use in combinatorial chemistry.

O uso de pastilhas de KBr em espectroscopia de infravermelho foi investigado para a monitorização de reações em fase sólida. A síntese do p-aminobenzoato de metila na Resina Merrifield (RM) é descrita como um modelo para esta técnica, a qual permite que o progresso das três etapas da síntese sejam monitoradas.

The use of KBr pellets in infrared spectroscopy has been investigated for monitoring solid-phase reactions. Synthesis of the methyl p-aminobenzoate on Merrifield resin (MR) is described as a model for this technique, which allows the progress of its three on-bead reaction steps to be monitored throughout their duration.

A Química Combinatória (QC) é atualmente uma das mais promissoras ferramentas para a descoberta e o desenvolvimento de novas moléculas com potencialidades terapêuticas. Nesta metodologia de síntese os produtos são formados simultaneamente e podem ser testados biologicamente em uma só vez, seja em forma de misturas ou separadamente. A principal meta desta nova metodologia é reduzir o tempo necessário para a obtenção de um novo fármaco. A síntese de quimiotecas pode ser realizada através da utilização de polímeros insolúveis, solúveis ou pela tradicional síntese em solução, sendo que cada uma delas apresenta características que podem ser vantajosas ou não, dependendo da metodologia utilizada. O desenvolvimento de técnicas de high throughput screening (HTS) devido às suas características peculiares necessita de tempo, razão pela qual a síntese de quimiotecas pequenas e racionais é enfatizada.

Nowadays, Combinatorial Chemistry is one of the most promising tools used in the design and discovery of new molecules potentially useful in the therapeutics. In this methodology, the reaction products are synthesized simultaneously and can be evaluated once, either in a complex mixture or as isolated compounds. The main aim of this new approach is the time for the development of new drugs. The synthesis of combinatorial libraries can be performed using either insoluble or soluble polymers and also by the traditional organic synthesis in solution. Each one of these approaches presents features that may be advantageous depending on the final objective of the synthetic process. The development of high throughput screening (HTS) assays takes much time, which makes the synthesis of small and well designed combinatorial libraries the most recommended strategy.

In the last decade we have seen improved a powerfull tool to medicinal chemistry: the Solid Phase Organic Synthesis (SPOS). This metodology can be used to synthesize a large library of compounds in a short time by combinatorial chemistry, where simple chemical substances can be combinated one to each other building a library of complex compounds. In this work we present the solid phase organic synthesis and their advantage upon the tradicional organic synthesis methodology, as well as the main polimers used in the SPOS technique.