The influence of the ring size of thiolactams in the Eschenmoser coupling reaction in presence of DBU. Formation of bicyclic thiazolidinones or thioimines

Russowsky, Dennis; Neto, Brenno Amaro da Silveira

doi:10.1016/j.tetlet.2003.12.049

Cited by 32 publications

(11 citation statements)

References 18 publications

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“…It has been reported [26] that the coupling between piperidine-2-thione and 2-bromo-2-phenylmethylacetate afforded the β-enaminocarbonyl in around 60% yield by using Eschenmoser sulfide contraction reaction and in most cases the bicyclic thiazolidinone was produced (4%-41%). [26] However, the possibility of by-product formation is very likely, as described before by Eschenemoser et al, [27] Neto [5,28] and others. [29][30][31] Compounds [(substituted imino)-4,9-dioxonaphtho- [2,3-d]thiazol-3-yl] heteroylamides 3a -3f show a characteristic red colour in solution, attributed to the local Push-Pull systems of conjugated double bonds and lone pairs.…”

Section: N-substitutedmentioning

confidence: 89%

Facile Synthesis of Naphtho[2,3‐d]thiazoles, Naphtho[2,3‐e][1,3,4]thiadiazines and Bis(naphtho[2,3‐d]thiazolyl)copper(II) Derivatives from Heteroylthiosemicarbazides

et al. 2016

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Section: N-substitutedmentioning

confidence: 89%

Facile Synthesis of Naphtho[2,3‐d]thiazoles, Naphtho[2,3‐e][1,3,4]thiadiazines and Bis(naphtho[2,3‐d]thiazolyl)copper(II) Derivatives from Heteroylthiosemicarbazides

et al. 2016

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“…While our attempts to prepare quinolizidines have been less successful, we have synthesised two simple lupin alkaloids, lupinine 12 and epilupinine 13 , in racemic form. [ 15 ] Although it might seem that reactions of the enaminones 5 and 6 should be directly comparable, we [ 15 , 16 ] and others [ 17 , 18 ] have previously found unexpected differences in the preparation and reactions of cyclic enaminones of different ring sizes. In this article we report our progress in preparing 1,4-disubstituted quinolizidine analogues of amphibian alkaloids by an extension of our approach to the synthesis of 5,8-disubstituted indolizidine alkaloids.…”

Section: Introductionmentioning

confidence: 95%

Analogues of amphibian alkaloids: total synthesis of (5R,8S,8aS)-(−)-8-methyl-5-pentyloctahydroindolizine (8-epi-indolizidine 209B)and[(1S,4R,9aS)-(−)-4-pentyloctahydro-2H-quinolizin-1-yl]methanol

Michael¹,

Accone²,

Koning³

et al. 2008

Beilstein J. Org. Chem.

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“…Furthermore, it is surprising that for this important substrate, its physical-chemical properties have hitherto not been described. Based on our interest in the study of PNP enzymes 15 and in the chemistry of biologically active compounds, [16][17][18][19] we describe herein an adapted synthesis and full spectroscopic characterization of 1. An insight into the phosphorolysis mechanism is also discussed based on electrospray ionization (tandem) mass spectrometry analysis.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and enzymatic evaluation of the guanosine analogue 2-amino-6-mercapto-7-methylpurine ribonucleoside (MESG): insights into the phosphorolysis reaction mechanism based on the blueprint transition state: SN1 or S N2?

Neto¹,

Lapis²,

Netz³

et al. 2010

J. Braz. Chem. Soc.

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A modificação experimental para a síntese do MESG (2-amino-6-mercapto-7-metilpurina ribonucleosídeo) 1 foi realizada com sucesso e sua caracterização total apresentada. ESI(+)-MSMS em alta resolução foram realizados indicando que a clivagem nucleosídica como principal e um possível mecanismo S N 1. Cálculos ab initio baseados em estados de transição blueprint corroboram com a proposta de um mecanismo S N 1 e descartam a possibilidade de um mecanismo S N 2. Ensaios com a enzima purina nucleosídica fosforilase (PNP, tanto humana como de M. tuberculosis) indicam a eficiência do substrato na reação de fosforilação do MESG e permitem a determinação de fosfato inorgânico em tempo real em ensaios biológicos.A modified experimental procedure for the synthesis of MESG (2-amino-6-mercapto-7-methylpurine ribonucleoside) 1 has been successfully performed and its full characterization is presented. High resolution ESI(+)-MSMS indicates both the nucleoside bond cleavage as the main fragmentation in the gas phase and a possible S N 1 mechanism. Ab initio transition state calculations based on the blue print transition state support this mechanistic rationale and discard an alternative S N 2 mechanism. Assays using purine nucleoside phosphorylase (PNP) enzyme (human and M. tuberculosis sources) indicate its efficiency in the phosphorolysis of MESG and allow the quantitative determination of inorganic phosphate in real time assay. Keywords: MESG, PNP enzyme, ESI, tuberculosisIntroduction 2-Amino-6-mercapto-7-methylpurine ribonucleoside 1 (MESG) is a very important substrate for the continuous spectrophotometric assay of inorganic phosphate and for measuring phosphate release kinetics in biological systems.1 In addition, 1 has been employed in the discovery of purine nucleoside phosphorylase (PNP) enzyme inhibitors.2 It has been established that this molecule is an important substrate for PNP and the kinetics of its phosphorolysis (or hydrolysis) can be conveniently followed spectrophotometrically in the range of 355-360 nm (Scheme 1).3 The PNP-catalyzed phosphorolysis of the guanosine analogue MESG (l max = 330 nm at pH 7.6) releases the free base 2-amino-6-mercapto-7-methylpurine 2 (l max = 360 nm at pH 7.6). 1 has also been used to monitor the activities of several ATPases. 4PNP is an enzyme of great importance and plays a role in clinical medicine, 5 especially because this enzyme is associated with profound immunodeficiency in T-cell function. 6,7 Further interest in this enzyme has significantly increased since the discovery that the congenital absence of its activity causes T-cell impairment in human beings, though keeping normal levels of B-cells. 8 Human PNPSynthesis and Enzymatic Evaluation of the Guanosine Analogue 2-Amino-6-mercapto-7-methylpurine J. Braz. Chem. Soc. 152 is therefore a target for the development of drugs to treat immunological disorders, such as rheumatoid arthritis, psoriasis, inflammatory bowel disorders and multiple sclerosis, and T-cell proliferative disorders, such as organ transplant rejecti...

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The influence of the ring size of thiolactams in the Eschenmoser coupling reaction in presence of DBU. Formation of bicyclic thiazolidinones or thioimines

Cited by 32 publications

References 18 publications

Facile Synthesis of Naphtho[2,3‐d]thiazoles, Naphtho[2,3‐e][1,3,4]thiadiazines and Bis(naphtho[2,3‐d]thiazolyl)copper(II) Derivatives from Heteroylthiosemicarbazides

Facile Synthesis of Naphtho[2,3‐d]thiazoles, Naphtho[2,3‐e][1,3,4]thiadiazines and Bis(naphtho[2,3‐d]thiazolyl)copper(II) Derivatives from Heteroylthiosemicarbazides

Analogues of amphibian alkaloids: total synthesis of (5R,8S,8aS)-(−)-8-methyl-5-pentyloctahydroindolizine (8-epi-indolizidine 209B)and[(1S,4R,9aS)-(−)-4-pentyloctahydro-2H-quinolizin-1-yl]methanol

Synthesis and enzymatic evaluation of the guanosine analogue 2-amino-6-mercapto-7-methylpurine ribonucleoside (MESG): insights into the phosphorolysis reaction mechanism based on the blueprint transition state: SN1 or S N2?

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