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Orientador : Ruiess V. F. Bravo Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica Mestrado

Orientador : Ruiess Van Fossen de Bravo Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica Doutorado

Kohleria eriantha has rhizomes which are underground stems with buds enclosed by modified leaves, that store starch. The buds of this rhizome can develop in two morphological patterns: an aerial shoot (similar to the mother plant) or a rhizome, depending on the water level present in the substrate. Development of the shoot was inhibited by low water availability (1 mL) in the substrate. It was verified that ethylene and ABA were involved in controlling the development of the rhizome pattern under low water availability. Treatments with ethrel, PEG and ABA induced shoot development whereas treatments with AgNO3 or AVG inhibited shoot development. Increased ethylene and ABA were observed under conditions that inhibited shoot development. Moreover, it is suggested that ABA may induce the production of ethylene in the sections of the rhizome under low water availability. Kohleria eriantha possui rizomas subterrâneos, caule com gemas envoltas por folhas modificadas que armazenam amido. As gemas desse rizoma podem-se desenvolver em dois padrões morfológicos: o padrão parte aérea (semelhante à planta mãe) ou um rizoma dependendo do nível de água do substrato. O desenvolvimento do padrão parte aérea foi inibido pela baixa disponibilidade de água do substrato (1 mL). Verificou-se que o etileno e o ABA estavam envolvidos com o controle do desenvolvimento do padrão rizoma na ausência ou baixa disponibilidade hídrica. Tratamentos com ethrel, PEG e ABA induziram o desenvolvimento do padrão parte aérea, enquanto os tratamentos com AVG e AgNO3 inibiram o desenvolvimento do padrão parte aérea. Observaram-se aumento de etileno e ABA sob condições que inibiram o desenvolvimento da parte aérea. Sugere-se, também, que ABA pode induzir a produção de etileno em seções do rizoma na ausência ou em baixa disponibilidade hídrica.

The reactions of 4-(methylamino)-3-penten-2-one with diazoketones yielded the α-acylenaminoketones 1–3 in good yields. Preparation of the α-acylenaminoketone 4 was carried out by treatment of 4-(t-butyl-amino)-3-penten-2-one with benzoyl chloride being followed by reaction of transamination with methyl-amine. The reactions were carried out in five different solvents and were submitted to gas chromatogra-phy/mass spectrometry analysis, with the goal of obtaining substituted pyrazoles and determining which of the carbonyls would preferentially be attacked by the nucleophile. The reactions of compounds 1–4 with hydrazine reagents led to the formation of the pyrazoles 5–7a-q. Small amounts of 4-methylamino-2-pentenones 10a-q, amides 11a-q and pyrazoles 12a-q were also obtained in these reactions. The unexpected formation of pyrazoles 15d,h,q was detected when methanol and N,N-dimethylformamide were used as solvents in the reactions of α-acylenaminoketone 4 with hydrazine reagents.

In this work, the reactivity of cyclopropenones toward N-acylamidine derivatives was investigated. Diphenylcyclopropenone reacted with N-benzoylacetamidine and N-(methoxycarbonyl)benzamidine affording 1,2-dihydro-3H-pyrrol-3-ones in moderate yields. However, alkylphenylcyclopropenone did not react. The formation of the compounds is examined mechanistically within frontier molecular orbital considerations. A reatividade de ciclopropenonas frente a derivados de N-acilamidinas foi investigada. Difenilciclopropenona reagiu com N-benzoilacetamidina e com N-(metoxicarbonil)benzamidina formando 1,2-diidro-3H-pirrol-3-onas em rendimentos moderados, porém alquilfenilciclopropenonas não reagiram com os mesmos nucleófilos investigados. A teoria dos orbitais moleculares de fronteira foi empregada para racionalizar a formação dos produtos.

The reactions of triphenylphosphoranylidenesuccinic anhydride with amines, hydrazines and dipolar nitrogen nucleophiles were investigated, and a new method of synthesis of phosphonioum salts containing the fragment RNHC(C=O)CH2CH2PPh3 is described. As reações do anidrido trifenilfosforanilidenossuccínico frente a aminas, hidrazinas e nucleófilos nitrogenados dipolares foram investigadas, o que levou ao desenvolvimento de um novo método de síntese de sais de fosfônio contendo o fragmento RNHC(C=O)CH2CH2PPh3 .

Low-energy collision-induc- ed dissociation (CID) and ion - mole- cule reactions with 2-methyl-1,3-dioxo- lane (MD) performed by pentaquadru- pole (QqQqQ) mass spectrometry were applied to locate the charge site in isomeric heteroaromatic cations. The 2-, 3-, and 4-pyridyl cations are indistin- guishable by CID. However, as suggest- ed by MS 3 experiments and ab initio calculations, the 2-pyridyl cation reacts extensively with MD by a transacetali- zation-like mechanism to afford a bicy- clic dihydrooxazolopyridyl cation. The 3- and 4-pyridyl cations, on the contrary, react predominantly with MD by proton transfer, as does the analogous phenyl cation. The 2-, 4-, and 5-pyrimidyl cati- ons display characteristic CID behavior. In addition, the 2-pyrimidyl cation re- acts extensively with MD by the trans- acetalization-like mechanism, whereas proton transfer occurs predominantly for the 4- and 5-pyrimidyl cations. The ions thought to be the 2- and 3-furanyl and 2- and 3-thiophenyl cations show in- distinguishable CID and ion - molecule behavior. This is most likely the result of their inherent instability in the gas phase and their spontaneous isomerization to the corresponding butynoyl and butyne- thioyl cations HCCHCH2CO a and HCCHCH2CS a . These isomeriza- tions, which are considerably exother- mic according to G2(MP2) ab initio calculations, are indicated by a series of experimental results. The ions dissociate upon CID by loss of CO or CS and undergo transacetalization with MD. Most informative is the participation of HCCHCH2CS a in a transacetaliza- tion/dissociation sequence with replace- ment of sulfur by oxygen, which is structurally diagnostic for thioacylium ions. It is therefore possible to locate the charge site of the 2-pyridyl and the three 2-, 4-, and 5-pyrimidyl cations and to identify the isomeric precursors from which they are derived. However, rapid isomerization to the common HCCH- CH2-CO(S) a ion eliminates character- istic chemical behavior that could result from different charge locations in the heteroaromatic 2- and 3-furanyl and 2- and 3-thiophenyl cations.

Enaminoketones and esters are gaining increased interest, particularly cyclic-β-enaminoesters, which are known as important intermediates for the synthesis of heterocycles and natural products, because the enantioselective preparation of highly functionalized compounds is of central importance in synthetic chemistry. Enaminones are versatile synthetic intermediates that combine the ambident nucleophilicity of enamines with the ambident eletrophilicity of enones. Enaminoketones and enaminonitriles have proven to be versatile building blocks for the synthesis of various heterocycles such as pyridine, pyrimidine and pyrrole derivatives. Enaminones systems have "enone" character, and may act as acceptors in both 1,2 and 1,4-additions. In this way the enaminone serves as a scaffold for annulation, and can gain access to systems such as pyrroles indolizidines, quinolizidines and perhydroindoles, all of which are common motifs in alkaloid structures. Enaminones are frequently employed as building blocks for the preparation of a variety of bicyclic compounds of biological interest and have been recently recognized as potential anticonvulsant compounds. Since a large number of developments in the use of enaminones in heterocyclic synthesis have occurred, a review of the recent developments in the synthetic approaches, covering the literature since 1995 until 2004, to these interesting molecules and their useful chemical transformations and biological activity can be considered of considerable value.

Reaction of 1-azirines 1a-d with diphenylketene afforded 1:1 adducts that were shown to be 5-pyrrolin-2-ones 3a-d . Some transformations of 3 are described.

By employing thiamine (vitamin B1) as the catalyst, a new “one-step” method for the synthesis of furil from furfuraldeyde has been developed. The method proved to be very promissing in preliminary studies thus indicating that several other diketones such as 2,2′ -pyridil-, 2,2′-thenil- and benzil-diketones can be obtained efficiently by the same approach. Additionally, it avoids the use of sodium cyanide, and shows much higher yields when compared to conventional methods.

The low energy collisional dissociation and ion/molecule chemistry of the heterocumulene cations OCN+CO 1 and OCCN+O 2 have been investigated by pentaquadrupole mass spectrometry, and G2(MP2) ab initio calculations applied to interrogate their relative stabilities and dissociation thresholds, as well as those of six other conceivable C2NO2+ isomers 3–8. The calculations show that the acyclic 1 (zero) and 2 (72.4 kcal mol–1) are the most stable isomers, whereas both the location of the positive charge mainly at the CO-carbon and the short CO bond lengths characterize their acylium ion structures. Two cyclic isomers, i.e. 7 (131.3 kcal mol–1) and 8 (140.0) kcal mol–1, were also found to be stable, but placed at energy levels considerably higher than 1. Exactly as predicted from G2(MP2) energy dissociation thresholds, low-energy collisions cause dissociation of 1 exclusively by CO loss to yield NCO+ of m/z 42. A more diverse dissociation chemistry is predicted and exhibited by 2, which dissociates mainly by loss of an oxygen atom (C2NO+ of m/z 54), CO (CNO+ of m/z 42) and C2O (NO+ of m/z 30). Both ions are unreactive towards polar [4+2+] cycloaddition with isoprene. However, they undergo ketalization with 2-methoxyethanol, and transacetalization with two cyclic neutral acetals, i.e. 2-methyl-1,3-dioxolane and 1,3-dioxane, and these structurally diagnostic ion/molecule reactions confirm experimentally the acylium ion structures of 1 and 2. Cyclic ‘ionic ketals’, i.e. 1,3-dioxonium ions, are formed in these reactions, as evidenced by their MS3 spectra, which show extensive dissociation to re-form the reactant ions. Whereas 1 readily forms a stable and covalently bound adduct with pyridine, 2 reacts mainly by net CN+ and OCN+ transfer via—most likely—the unstable (Py–2)+ adduct.

Reduction of oximes 4, obtained from 1,5 di-hydro-2H-pyrrol-2-ones 3, with Raney nickel “generated in situ” afforded pyrrolo [3,2b] pyrrolone derivatives 6 and 7 and, in some cases, amines 5. The reduction of 4 with W7 Raney nickel afforded only amines 5. Mechanistic aspects of these reductions were investigated The formation of 6 and 7 is attributed to the deactivation of the catalyst by sodium hydroxide.

The results of semiempirical molecular orbital calculations performed on several cyclopropenones employing the MNDO, AM1, and PM3 molecular models are presented. The AM1 method, which best reproduces structural properties, is used to calculate electronic parameters for a series of cyclopropenones. The use of these parameters for the evaluation of reactivity is discussed.

The mild base-promoted reaction of methyl 2-phenyl-1-azirine-3-acetate (1) with aldehydes and acetone provides a new and simple route to the 3-oxazolines 5, which are formed in good yields by the electrophilic trapping of an imino anion produced by C-N bond cleavage in the 1-azirine enolate intermediate 6. Chloranil oxidation of 5 containing an aromatic substituent at C-2 affords oxazoles 7, while reaction of 5 containing an aliphatic group at C-2 produces 5-methylene-3-oxazolines 8 and 5-spiro-2-oxazolines 9 in addition to 7.

A high-transmission Extrel pentaquadrupole mass spectrometer was interfaced to an IBM-compatible microcomputer, and a variety of object-oriented programs in the Microsoft Windows operating system were developed to operate and to increase the versatility of the instrument. A selective prescan procedure and the complete control of all three mass-scanning quadrupoles made possible very fast acquisition of several types of three- and four-dimensional MS2 and MS3 spectra, while the high transmission of the quadrupoles conferred excellent signal-to-noise levels to both MS2 and MS3 spectra. By performing an unrestricted third-order (MS3) experiment through scanning of the three mass-analyzer quadrupoles, an entire MS3 data domain was acquired, and the results were collected in the first 4D MS3 mass spectrum. Data projection and data extraction procedures were applied to the 4D spectrum, each of which yielded spectra that provide very specific analytical information. The applicabilities of this and several other ...

This paper describes the use of a moving median filter in chemical applications. A probabilistic approach shows the performance in elimination of outliers. The principal advantage over linear filters is the elimination of outliers without significant deformation of the analytical signal. A decrease in level of the normal random noise is also observed. However, the attenuation is lower that obtained by using the moving average with the same smoothing interval size and it is dependent of derivative of the signal. A characteristic of this method is that the peaks are not broadened, however their tops can be cut off.

The synthetic usefulness of a new method of 1,2,3-triazole synthesis has been demonstrated. By employing cyclic enamino esters 3 and enamino ketones 4 in reactions with 5,7-dinitro-3-diazo-1,3-dihydro-2H-indol-2-one (1), bicyclic triazoles 5 and 6 have been prepared in good to excellent yields.

A new and efficient method of 1,2,3-triazole synthesis is described in which these heterocyclics are formed through a novel nitrogen transfer from diazocarbonyl compounds to enaminones. Thus, the reaction of 3-diazo-1,3-dihydro-2H-indol-2-one derivatives 1 (X = NR3) and 3-diazobenzo[6]thiophen-2(3H)-one 5 (X = S) with enaminones 2 and 7 leads to the formation of mainly 1,2,3-triazoles 4 and pyrazoloquinazolinones 3. Both the phenyl substituants (Y and Z in 1) and the nature of the X group affects the reaction rate and product distribution. Rate increases with an increase in the electron-withdrawing ability of the substituants Y and Z. The dinitro derivative 1g is shown to be the most efficient in promoting 1,2,3-triazole 4 formation while pyrazoloquinazolinones 3 are often competitively formed when other derivatives of 1 are employed. © 1993 American Chemical Society.

Methylphenylcyclopropenone ( 1 ) reacts with pyrazole and 3,5-dimethylpyrazole to afford ketones ( 2 ) resulting from initial nucleophilic attack at methyl-C, in agreement with an AM1 calculation performed on 1 . Intermediacy of dipolar species 3 accounts for products and allows incorporation of other nucleophiles (2-aminothiazoole, 2-amino-4-methylpyridine, and o-phenylenediamine).

A previous report involving 1 H nmr spectra of some 1-phenyl and 1-benzoyl 3(2-pyridyl)thioureas was reinvestigated and found to be incorrect. Analysis of the data permits the designation of preferred conformations for these systems

Methylphenylcyclopropenone ( 1 ) reacts with pyrazole and 3,5-dimethylpyrazole to afford ketones ( 2 ) resulting from initial nucleophilic attack at methyl-C, in agreement with an AM1 calculation performed on 1 . Intermediacy of dipolar species 3 accounts for products and allows incorporation of other nucleophiles (2-aminothiazoole, 2-amino-4-methylpyridine, and o-phenylenediamine).

The regiochemistry of the previously reported dimer of methyhlphenylcyclopropenone is corrected through analysis of the long-range 1 H, 13 C correlated (COLOC) 2D nmr spectrum

A new and efficient method of 1,2,3-triazole synthesis is described in which these heterocyclics are formed through a novel nitrogen transfer from diazocarbonyl compounds to enaminones. Thus, the reaction of 3-diazo-1,3-dihydro-2H-indol-2-one derivatives 1 (X = NR3) and 3-diazobenzo[6]thiophen-2(3H)-one 5 (X = S) with enaminones 2 and 7 leads to the formation of mainly 1,2,3-triazoles 4 and pyrazoloquinazolinones 3. Both the phenyl substituants (Y and Z in 1) and the nature of the X group affects the reaction rate and product distribution. Rate increases with an increase in the electron-withdrawing ability of the substituants Y and Z. The dinitro derivative 1g is shown to be the most efficient in promoting 1,2,3-triazole 4 formation while pyrazoloquinazolinones 3 are often competitively formed when other derivatives of 1 are employed. © 1993 American Chemical Society.

The synthetic usefulness of a new method of 1,2,3-triazole synthesis has been demonstrated. By employing cyclic enamino esters 3 and enamino ketones 4 in reactions with 5,7-dinitro-3-diazo-1,3-dihydro-2H-indol-2-one (1), bicyclic triazoles 5 and 6 have been prepared in good to excellent yields.

The reactions of carbethoxycarbene (:CH2-CO2Et, 2) with several acyclic enaminones (RCOCH=CR1NHR2, 3) lead to the unexpected formation of 2-Me, 3-CO2Et, 4-H, 5-R1-pyrroles 4. Structural variations of the enaminones show that the structural fragments C(3)-CO2Et and C(2)-Me are provided by 2 and that the fragment C(5)-R1NHR2 originates from the enaminones 3, while the RCO group from 3 is eliminated during the course of reaction. Reactions with cyclic and nitrogen-hindered enaminones do not lead to pyrrole formation but occur by simple insertion of 2 to the Cα-H bond.

The mild base-promoted reaction of methyl 2-phenyl-1-azirine-3-acetate (1) with aldehydes and acetone provides a new and simple route to the 3-oxazolines 5, which are formed in good yields by the electrophilic trapping of an imino anion produced by C-N bond cleavage in the 1-azirine enolate intermediate 6. Chloranil oxidation of 5 containing an aromatic substituent at C-2 affords oxazoles 7, while reaction of 5 containing an aliphatic group at C-2 produces 5-methylene-3-oxazolines 8 and 5-spiro-2-oxazolines 9 in addition to 7.

By employing thiamine (vitamin B1) as the catalyst, a new “one-step” method for the synthesis of furil from furfuraldeyde has been developed. The method proved to be very promissing in preliminary studies thus indicating that several other diketones such as 2,2′ -pyridil-, 2,2′-thenil- and benzil-diketones can be obtained efficiently by the same approach. Additionally, it avoids the use of sodium cyanide, and shows much higher yields when compared to conventional methods.

Reduction of oximes 4, obtained from 1,5 di-hydro-2H-pyrrol-2-ones 3, with Raney nickel “generated in situ” afforded pyrrolo [3,2b] pyrrolone derivatives 6 and 7 and, in some cases, amines 5. The reduction of 4 with W7 Raney nickel afforded only amines 5. Mechanistic aspects of these reductions were investigated The formation of 6 and 7 is attributed to the deactivation of the catalyst by sodium hydroxide.

Reaction of 1-azirines 1a-d with diphenylketene afforded 1:1 adducts that were shown to be 5-pyrrolin-2-ones 3a-d . Some transformations of 3 are described.

New pyrrolizidine derivatives 6 and 7 were prepared from the 1, 5-dihydro-2H-pyrrol-2-one 3a via an acidic intramolecular aldol condensation in 16% and 42% yields, respectively. Compound 6 was obtained by dehydration of 7 with p-toluenessulfonic acid in 67% yield.

2-Formyl-2H-azirine-N-arylimines 1a-c react with diphenylketene 2 to afford 2H-2-azirinyl-2-azetidi-nones 3a-c and N-aryldiphenylacetamides 4a-c by reaction at the exo-imine group. Derivatives containing the bulkier methyl group at the 2-position, 1d-f, produce only 4a-c.

The reactions of 4-(methylamino)-3-penten-2-one with diazoketones yielded the α-acylenaminoketones 1–3 in good yields. Preparation of the α-acylenaminoketone 4 was carried out by treatment of 4-(t-butyl-amino)-3-penten-2-one with benzoyl chloride being followed by reaction of transamination with methyl-amine. The reactions were carried out in five different solvents and were submitted to gas chromatogra-phy/mass spectrometry analysis, with the goal of obtaining substituted pyrazoles and determining which of the carbonyls would preferentially be attacked by the nucleophile. The reactions of compounds 1–4 with hydrazine reagents led to the formation of the pyrazoles 5–7a-q. Small amounts of 4-methylamino-2-pentenones 10a-q, amides 11a-q and pyrazoles 12a-q were also obtained in these reactions. The unexpected formation of pyrazoles 15d,h,q was detected when methanol and N,N-dimethylformamide were used as solvents in the reactions of α-acylenaminoketone 4 with hydrazine reagents.