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STRATEGIES FOR THE SYNTHESIS OF LYSERGIC ACID. (+)-Lysergic acid [(+)-1] is a precursor of several substances with well-established pharmacological properties, including some drugs approved and commercialized around the world. Thus, the importance of (+)-1 as a synthetic target becomes undoubted and various strategies for the synthesis of its tetracyclic core have been reported in the literature. Therefore, in this review article we will address in chronological order the total and formal syntheses of lysergic acid (1), separating them into racemic and chiral/asymmetric syntheses. Until now, there are 24 syntheses described in the literature, namely, 11 total and 13 formal syntheses. Considering all the syntheses accomplished, 15 were planned to produce (±)-lysergic acid [(±)-1] and 9 presented routes to eventually provide (+)-lysergic acid [(+)-1]. A significant evolution regarding approaches and efficiency may be observed since the first synthesis of (±)-1 until the last asymmetric synthesis of (+)-1.

Aporphine compounds constitute a class of substances with important pharmacological properties, including anticancer, antiviral, anti-HIV, anti-inflammatory, and leishmanicidal activities. Consequently, several strategies to obtain the aporphine core have been reported. Herein this review, we provide an overview of two relevant approaches used to construct the C-ring in the synthetic routes developed. The first approach, which is based on a one-bond disconnection, allows C-ring formation using a 1-benzyl-1,2,3,4-tetrahydroisoquinoline intermediate (mainly) employing cyclization reactions catalyzed by metals or promoted by light. The second approach, which is derived from a two-bond disconnection, leads to C-ring formation via a sequence of reactions starting with [4+2] cycloadditions. Through these approaches, aporphinoids with a diverse range of substitution patterns and biological activities can be synthesized.

A class of aryne precursors, that is, 2-(trimethylsilyl)aryl 4-chlorobenzenesulfonates, has been developed through well-established synthetic routes, which allow the formation of arynes under relatively mild conditions. All the aryne precursors were obtained from phenols and 4-chlorobenzenesulfonyl chloride, an inexpensive and easy-to-handle reagent with relatively low toxicity, and subjected to nucleophilic addition reactions, providing addition products in yields of 24 to 92%, and to cycloaddition reactions, affording cycloadducts in yields up to 80%. This work provides interesting insights into the mechanisms of aryne generation. In addition, 2-(trimethylsilyl)phenyl 4-chlorobenzenesulfonate was successfully employed in the total synthesis of (±)-aporphine.

A biomimetic iodofunctionalization of aromatic and heteroaromatic compounds has been developed using NaI as a source of iodine and 30% H2O2 as a mild oxidant, as well as SeCl4 as a commercially available catalyst in water without a co-solvent. The method affords iodinated compounds in isolated yields of 37 to 99%. The catalytic system has potential for the bromination of aromatic substrates.

In the present work we developed a practical, faster, and more sustainable way to prepare conjugated materials, derived from poly-p-phenylenes (PPPs), using 10% palladium on carbon as catalyst and distilled water as solvent under microwave heating for 3 h. The oligomers were also prepared by the classical Suzuki reaction to enable a comparison of results. All materials were characterized by nuclear magnetic resonance (NMR), infrared (IR), absorption and emission analysis, gel permeation chromatography (GPC), and thermogravimetric analysis. The polymers prepared by the alternative method were obtained in higher yields than the polymers produced by the classical Suzuki reaction. In addition, characterization data showed no significant differences in terms of molecular structures and luminescent properties between the polymers synthesized through the different protocols. Therefore, the alternative method developed was considered appropriated for the synthesis of PPPs derivatives.

Convergent total synthesis of (±)-apomorphine hydrochloride was accomplished by an approach that employs in the key step a sequence of transformations involving a [4+2]-cycloaddition reaction followed by a hydrogen migration. Through this sequence of transformations, the desired aporphine core was obtained regioselectively in 75% isolated yield. Since only one regioisomer was produced in the key step of the synthesis, a polar [4+2]-cycloaddition mechanism was proposed. Furthermore, NMR experiments and theoretical calculations were carried out to elucidate the hydrogen migration mechanism. (±)-Apomorphine hydrochloride was achieved after 9 steps in an overall yield of 8% involving benzyne chemistry.

Total syntheses of (+)-bernumidine and its unnatural enantiomer were accomplished through chemoenzymatic dynamic kinetic resolution and ruthenium(II)-catalyzed enantioselective hydrogenation, which provided (R)-salsolidine propyl carbamate and N-acetyl (S)-salsolidine in high yields and enantiomeric excesses, respectively. Both enantiomers of salsolidine were accessed and converted into (+)- and (−)-bernumidine via simple and efficient transformations.

Purpose Among alkaloids, abundant secondary metabolites in plants, aporphines constitute a class of compounds with interesting biological activities, including anticancer effects. The present study evaluated the anticancer activities of 14 substances, including four aporphine derivatives acquired through the biomonitoring of (±)-apomorphine hydrochloride total synthesis from 2-phenethylamine and 3,4-dimethoxybenzaldehyde against head and neck squamous cell carcinoma (HNSCC). Methods The cytotoxic effects of compounds against a panel of HNSCC cell lines were determined by PrestoBlue cell viability assay, while the genotoxicity of substances was evaluated by micronucleus test. Cell death was detected by flow cytometry (Annexin V/7AAD) and western blot analysis was used to detect the presence of cleaved Caspase-3 molecules. Results The aporphine and isoquinoline derivatives APO, C1, and A5 significantly reduced HNSCC cell viability and promoted DNA damages in these cells. Further, by activating the Caspase-3 pathway, these substances were able to induce apoptosis. Conclusion Our results revealed that APO, C1, and A5 exhibit cytotoxic effects in HNSCC cells. The mechanisms of action appear to be partly via the generation of DNA damages and apoptosis induction through Caspase-3 pathway activation. This study provides preclinical data that suggest a potential therapeutic role for APO, C1, and A5 against head and neck cancer cells.

A modular approach for the synthesis of functionalized silylbiaryl triflates has been developed. Iodinated silylaryl triflates were prepared via a gram-scale diiodination reaction, followed by a one-flask transformation, in 42–52% overall yield. The iodinated silylaryl triflates were subjected to a novel chemoselective Suzuki reaction with arylboronic acids, using PdCl2(PPh3)2 as catalyst and K2CO3 as base in THF/H2O (1:1) at 80 °C for 24 hours, which afforded silylbiaryl triflates in 47–81% yield.

Total syntheses of (S)- and (R)-nuciferine were accomplished through approach involving diastereoselective reaction between a chiral dihydroisoquinoline enamide and 2-(trimethylsilyl)phenyl trifluoromethanesulfonate promoted by CsF, affording a separable mixture of diastereoisomers, which provided (S)- and (R)-nuciferine via simple and efficient transformations.

Aim: Considering the epidemiology of leishmaniasis, the emergence of resistant parasites to the approved drugs, and severe clinical manifestations, the development of novel leishmanicidal molecules has become of considerable importance. Results: In this work, three commercially available and 19 synthesized quinoline derivatives were evaluated against promastigote and amastigote forms of Leishmania (Leishmania) amazonensis. In addition, structural parameters and molecular electrostatic potentials were obtained by theoretical calculations, allowing statistical (principal component analyses and hierarchical cluster analyses) and comparative (molecular electrostatic potentials vs leishmanicidal activities) studies, respectively. Conclusion: Principal component analyses and hierarchical cluster analyses suggested volume and polar surface area as possible structural descriptors for the leishmanicidal activity. Furthermore, a comparison between molecular electrostatic potentials and leishmanicidal activities afforded a reasonable structure–activity relationship.

Total synthesis of ( R )-aporphine has been accomplished by an approach that employs in the key step a sequence of transformations involving a [4+2] cycloaddition reaction followed by a hydrogen migration, leading to aporphine core in good yield, which was subjected to a 1D gradient NOE experiment, conformational analysis, and simple transformations, including a small scale resolution process, to afford enantiomerically enriched aporphine alkaloid.

This study investigated the synthesis and structural characterization of two new polymeric frameworks based on metalorgano-chalcogenide materials. X-ray analyses revealed the frameworks of prepared compounds 1 and 2 to be polymeric chains achieved through Se–Hg intermolecular interactions. A detailed Raman evaluation of the compounds was performed, showing their synthetic precursors to constitute a safe and reproducible model for the assignment of the main vibrational modes of the molecules investigated. Complete characterization of 1 and 2 also included elemental analysis, IR spectroscopy, UV–Vis absorption data, and EDX analysis.

Total syntheses of lysicamine, (±)-nuciferine, (±)-nornuciferine, (±)-zanthoxyphylline iodide, (±)-O-methylisothebaine, and (±)-trimethoxynoraporphine were accomplished by an approach that involves the formation of aporphine cores through reactions between an isoquinoline derivative and silylaryl triflates promoted by CsF. Unprecedented formations of aporphine cores proceeded in good yields presumably through [4 + 2] cycloaddition reactions followed by hydrogen migrations.

In the present paper the synthesis and optical characterization of iodinated acetophenone, 4-hydroxy-3-iodoacetophenone and 4-hydroxy-3,5-diiodoacetophenone obtained from 4-hydroxyacetophenone, were carried out. The optical features of iodinated molecules were determined by performing the UV-Vis absorption, fluorescence and thermal lens spectroscopies. The results showed that the optical properties of the 4-hydroxyacetophenone is altered when the iodine atom is inserted, as substituent, in the aromatic ring. Although it was determined that the optical feature was changed when one iodine atom was inserted in the aromatic ring (4-hydroxy-3-iodoacetophenone), the results revealed that emission behavior was strongly altered when two iodine atoms (4-hydroxy-3,5-diiodoacetophenone) were acting as substituents: the fluorescence quantum efficiency increases approximately 60%.

Nowadays, dengue fever, a mosquito-borne tropical disease, has become widely distributed in Brazil. In order to prevent such disease, the population of Aedes aegypti mosquito has to be controlled. Then, the aim of this study is to assess the toxicological effects of phenolic compounds against dengue mosquitos. Hence, the larvicidal activity and toxicity of phenolic compounds against Ae. aegypti larvae and A. salina, are evaluated, respectively. The phenolic compounds 2,6-diiodophenol and 4-chloro-2,6-diiodophenol have different toxicity and larvicidal activity. The compound 4-chloro-2,6-diiodophenol shows the highest toxicity for larvae of Ae. aegypti, exhibiting higher toxicity than 2,6-diiodophenol. Although less toxic than Temephos®(organophosphate), the phenolic compounds evaluated by this research, are proved to be effective against Ae. aegypti larvae. This study demonstrates the importance of controlling the dengue mosquito, considering toxicological aspects of phenolic compounds to prevent environmental impacts.

An electrophilic iodocyclization reaction involving alkynylated 2-iodoanisoles and molecular iodine in the presence of sodium bicarbonate was developed and diiodo-functionalized benzo[b]furans were obtained in yields from 45 to 99%.

3-(Thiophen-2-yl)-4,5-dihydro-1H-pyrazole-1-carboximidamides were efficiently prepared through a cyclocondensation of thiophenylchalcones with aminoguanidine hydrochloride under ultrasonic conditions in the presence of KOH and ethanol as a green solvent in short reaction times (15-35 min) and good yields (62-95%). All compounds produced were evaluated against the human Jurkat and RS4;11 acute lymphoblastic leukemia cell lines of T- and B-cell origin, respectively, and the K562 myelogenous leukemia cell line. Six compounds presented half maximal inhibitory concentration (IC50) values around 15 µmol L-1 and five compounds presented IC50 values around 40 µmol L-1 for at least one of the three cell lines analyzed. One compound was not significantly cytotoxic, presenting IC50 value > 100 µmol L-1.

Enzymatic kinetic resolution of organofluorine rac -alcohols by CALB yielded (−)-( R )-2,2,2-trifluoro-1-phenylethanol ( 2a ), (−)-( R )-1-(3-bromophenyl)-2,2,2-trifluoroethanol ( 2b ), (−)-( R )-1-(4-bromophenyl)-2,2,2-trifluoroethanol ( 2c ), (−)-( S )-1-(2,4,5-trifluorophenyl)ethanol ( 2d ), (+)-( S )-2,2,2-trifluoro-1-phenylethyl acetate ( 3a ), (+)-( S )-1-(3-bromophenyl)-2,2,2-trifluoroethyl acetate ( 3b ), (+)- (S )-1-(4-bromophenyl)-2,2,2-trifluoroethyl acetate ( 3c ) and (+)-( R )-1-(2,4,5-trifluorophenyl)ethyl acetate ( 3d ) in high enantiomeric excess (up to >99% ee ). The reactions were conducted under conventional conditions (orbital shaking) and microwave irradiation in toluene and vinyl acetate as acylating agent. The CALB showed excellent selectivities and good yields in the transesterification of fluorinated aromatic compounds.

In this review article we have gathered relatively recent publications involving modern methodologies for iodi- nation reactions of aromatic and heteroaromatic compounds using pure water or mixtures containing water as environ- mentally friendly media.

The reaction of aromatic and heteroaromatic compounds with molecular iodine in the presence of aqueous hydrogen peroxide using water without any co-solvent at 50 °C for 24 h produced versatile iodinated organic molecules with potential application in organic synthesis and medicine in very good yields. In addition, a mechanistic investigation for the iodination process was carried out by mass spectrometry.

In this work, the formation and characterisation of two new isostructural metal–organochalcogen clusters from simple starting materials was investigated. A sonochemical synthesis was performed in a one-pot procedure without the isolation of synthetic intermediates. This methodology offers a new approach to prepare cluster compounds, and this experiment led to the formation of [(PhTe)12Hg8(S)X2(Py)2]·Py (X = Br, I; Py = Pyridine) in good yield. The X-ray analyses reveal that the framework of the clusters contains a similar [Hg8(μ4-S)Te12] core as the central unit. The sulphur atom present in the core of both structures has a tetrahedral coordination geometry achieved by four S–Hg(II) bonds. The complete characterisation of the synthesised materials also includes elemental analyses, IR spectroscopy and UV–Vis absorption data.

Nine marine fungi (Aspergillus sclerotiorum CBMAI 849, Aspergillus sydowii Ce19, Beauveria felina CBMAI 738, Mucor racemosus CBMAI 847, Penicillium citrinum CBMAI 1186, Penicillium miczynskii Ce16, P. miczynskii Gc5, Penicillium oxalicum CBMAI 1185, and Trichoderma sp. Gc1) catalyzed the asymmetric bioconversion of iodoacetophenones 1-3 to corresponding iodophenylethanols 6-8. All the marine fungi produced exclusively (S)-ortho-iodophenylethanol 6 and (S)-meta-iodophenylethanol 7 in accordance to the Prelog rule. B. felina CBMAI 738, P. miczynskii Gc5, P. oxalicum CBMAI 1185, and Trichoderma sp. Gc1 produced (R)-para-iodophenylethanol 8 as product anti-Prelog. The bioconversion of para-iodoacetophenone 3 with whole cells of P. oxalicum CBMAI 1185 showed competitive reduction-oxidation reactions.

The reaction between 2,6-dihalophenols and 2-(trimethylsilyl)aryl triflates in the presence of CsF using acetonitrile as solvent at room temperature led to the formation of functionalized diaryl ethers in very good yields.

In this work we have investigated the reaction for the obtention of an uncommon complex salt of the organotellurium bromide class. The reaction was carried out without the isolation of the synthetic intermediates in one-pot procedure. The complex salt obtained presents the tellurium atoms with mixed oxidation states (TeII and TeIV). The cationic unit [5-Br-2-CH3O–C6H3Te(ETU)]+ presents the TeII atom with a “T” shape coordination geometry, and the anionic unit [4-CH3O–C6H4TeBr4]− presents the TeIV atom with an octahedral coordination geometry considering the Te···Br interaction of 3.600(6) A from the dimeric arrangement presented in the solid state. Intermolecular (Te···Br) secondary bonds, built up the crystalline/molecular structure. Solution NMR data are presented and discussed in the light of the X-ray structure.

A simple and selective reaction for the preparation of iodinated phenols was developed and phenol derivatives containing electron withdrawing groups were iodinated in very good yields under relatively mild conditions. Uma reação simples e seletiva para a preparação de fenóis iodados foi desenvolvida e derivados fenólicos contendo substituintes eletroretiradores foram iodados em rendimentos muito bons sob condições relativamente brandas.

The [3+2] cycloaddition of a variety of diazo compounds with o-(trimethylsilyl)aryl triflates in the presence of CsF or TBAF at room temperature provides a very direct, efficient approach to a wide range of potentially biologically and pharmaceutically interesting substituted indazoles in good to excellent yields under mild reaction conditions. Simple diazomethane derivatives afford N-unsubstituted indazoles or 1-arylated indazoles, depending upon the stoichiometry of the reagents and the reaction conditions, while dicarbonyl-containing diazo compounds undergo carbonyl migration to afford 1-acyl or 1-alkoxycarbonyl indazoles selectively.

Mannich base derivatives 1–3 were biotransformed through tandem enzymatic reactions by using several microorganisms isolated from Brazilian biomes. The hydrochlorides 1 and 3 produced propiophenone 1a, α,β-unsatured ketone 2c and alcohol (S)-1b (yield 40%, e.e. 81%, Aspergillus terreus). The hydrochloride 2 underwent the Baeyer–Villiger oxidation producing exclusively para-methoxy-phenol by A. terreus and A. niger. The propiophenone 1a was reduced to their corresponding enantiomerically enriched phenylpropanol (S)-1b (yield 65%, e.e. 81%, A. terreus). The para-methoxy-propiophenone 2a afforded Baeyer–Villiger reaction hydrolyzed product, the para-methoxy-phenol (yield 80%, A. terreus). The racemic phenylpropanols 1b,2b were resolved by lipase-catalyzed kinetic resolution (Novozym 435) affording (S)-alcohols 1b,2b and (R)-acetates 1d,2d in high enantiomeric excesses (up to 99%) and good yields (40–45%). We screened new microorganisms in biotransformation of Mannich bases, propiophenones and applied enzymatic resolution of phenylpropanols by Candida antarctica lipase.

A facile, one-pot, ultrasound-promoted synthesis of N-substituted 5-(3,3,3-trifluoro-2-oxopropylidene)pyrrolidin-2-ones from methyl 7,7,7-trifluoro-4-methoxy-6-oxohept-4-enoate and a wide range of primary alkyl(aryl)amines using ethanol as a green solvent and employing triethylamine as a base is described.

Z-Vinylic tellurides react with metal acetylides under nickel complexes catalysis to give Z-enynes and Z-enediynes in good yields.

The pathways for the oxidation of tartaric acid and citric acid by vanadium(V) in perchloric acid medium have been studied at 303 K by following the formation of vanadium(IV) spectrophotometrically at 760 nm. The oxidation reaction displays fractional order dependence with respect to both the α-hydroxy acids concentrations as well as fractional (tartaric acid) and first order (citric acid) dependencies with respect to the perchloric acid concentration. It does not matter at all whether the ionic strength was varied or was maintained constant. The reaction rate remains essentially constant with increasing ionic strength in the tartaric acid oxidation, but decreases slightly in the citric acid case. A decrease of the dielectric constant of the reaction medium results in a rate decrease in the tartaric acid oxidation and in a rate enhancement in the citric acid reaction. The activation parameters were obtained from studies of the reactions at different temperatures (293 to 313 K). Based on the experimentally determined rate laws oxidation mechanisms and theoretical rate laws were proposed.

A series of twelve novel 2-(pyrazol-1-yl)pyrimidine derivatives was easily obtained under ultrasonic conditions by the cyclocondensation reaction of 1-carboxamidino-pyrazoles with 4-methoxyvinyl-trifluoromethyl ketones using ethanol as an environment-friendly solvent in the presence of potassium hydroxide. Comparison of the ultrasound-promoted reaction with classical methodology shows that the former is faster and gives better yield. The products were isolated in excellent purity grades without purification by chromatography or recrystalization.

A facile, one-pot, ultrasound-promoted synthesis of N-substituted 5-(3,3,3-trifluoro-2-oxopropylidene)pyrrolidin-2-ones from methyl 7,7,7-trifluoro-4-methoxy-6-oxohept-4-enoate and a wide range of primary alkyl(aryl)amines using ethanol as a green solvent and employing triethylamine as a base is described.

A rapid and efficient ultrasound-promoted protocol for iodination of aromatic and heteroaromatic compounds, using molecular iodine in the presence of aqueous hydrogen peroxide in water without any cosolvent, has produced versatile iodinated organic molecules with potential application in organic synthesis and medicine in short reaction times and good to excellent yields.

The citric acid oxidation by vanadium(V) in sulfuric acid medium at 303 K is reported. The reaction rate was determined spectrophotometrically by monitoring the formation of vanadium(IV) at 760 nm. The oxidation showed a first-order dependence with respect to vanadium(V) concentration and fractional order with respect to citric acid concentrations, with no control and with constant ionic strength. The reaction is also first order with respect to sulfuric acid concentration with no control and of fractional order at constant ionic strength. The reaction rate is enhanced by an increase of ionic strength and increased by a decrease of the dielectric constant. The activation parameters were calculated based on the rate constants determined in the 293 to 313 K interval. The proposed oxidation mechanisms and the derived rate laws are consistent with the experimental rate laws. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 566–572, 2000

The ring opening reaction of N-tosyl aziridines with dilithium arylthienylcyanocuprates generated from arylbutyltellurides produced phenethylamine derivatives in good to excellent yields.

A rapid and efficient ultrasound-promoted protocol for iodination of aromatic and heteroaromatic compounds, using molecular iodine in the presence of aqueous hydrogen peroxide in water without any cosolvent, has produced versatile iodinated organic molecules with potential application in organic synthesis and medicine in short reaction times and good to excellent yields.

The coupling reaction between 2,6-diiodoanisoles and terminal alkynes using Pd(PPh3)2Cl2 and CuI as catalysts and diisopropylamine as base in toluene at room temperature for 12 h produced selectively alkynylated 2-iodoanisoles, in good to excellent yields (52-95%), which are useful building blocks with potential application in the synthesis of functionalized benzo[b]furans. A reação de acoplamento entre 2,6-diiodoanisóis e alcinos terminais usando Pd(PPh3)2Cl2 e CuI como catalisadores e diisopropilamina como base em tolueno a temperatura ambiente por 12 h produziu seletivamente 2-iodoanisóis aquinilados, em rendimentos de bons a excelentes (52-95%), os quais são blocos de construção úteis com potencial aplicação na síntese de benzo[b]furanos funcionalizados.

Due to the great importance of benzyne as a highly reactive intermediate in organic chemistry, with applications in total syntheses 1 and in preparations of functional materials, 2 we intend to accomplish the convergent total synthesis of the aporphine alkaloid PO-3 (1), a natural dye of green color, 3 employing as key reaction a [4+2] cycloaddition between 1-methylene-1,2,3,4-tetrahydroisoquinoline (3) and the benzyne derivative 7, formed from 2-(trimethylsilyl)aryl triflate (8), under mild reaction conditions.

Benzyne can be considered a highly reactive intermediate with application in reactions of insertion into sigma bonds and also in cycloaddition reactions, which have been broadly employed in total syntheses of bioactive natural products1 and in preparations of functional materials.2 Accordingly, we intend to accomplish the total synthesis of aporphine alkaloid named lysicamine (1),3 a compound with antileishmanial activity,4 employing strategy which has as key step the [4+2] cycloaddition reaction between 1-methylene-1,2,3,4tetrahydroisoquinoline (3) and benzyne (7), generated from 2-(trimethylsilyl)phenyl triflate (8), under mild reaction conditions.

Owing to the considerable importance of benzyne as highly reactive intermediate in organic chemistry, with applications in total syntheses 1 and in preparations of functional materials, 2 we intend to synthesize the 3-hydroxy-2-(trimethylsilyl)phenyl trifluoromethanesulfonate (6), envisioning the employment of such aryne precursor in reactions of insertion into sigma bonds, in cycloaddition reactions and in the total synthesis of bioactive natural products.

th Brazilian Meeting on Organic Synthesis – 14 th BMOS – September 01-05, 2011-Brasilia, Brazil Ultrasound-promoted iodination of aromatic compounds in the presence of iodine and hydrogen peroxide in water. Irlon M. Ferreira, Rafael D. C. Gallo, Gleison A. Casagrande, Lucas Pizzuti* and Cristiano Raminelli* Faculdade de Ciencias Exatas e Tecnologia, Universidade Federal da Grande Dourados, Dourados, MS, Brazil *e-mail addresses: lucaspizzuti@ufgd.edu.br or raminelli@ufgd.edu.br