cis- and trans-Piperlyenes<sup>1,2</sup>

Frank, Robert; Emmick, R. D.; Johnson, Rayner S.

doi:10.1021/ja01202a020

Cited by 50 publications

(14 citation statements)

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“…Our approach to (−)- 3 is shown in Scheme . The known racemic anhydride 5 is readily available from the Diels−Alder reaction of piperylene with maleic anhydride, followed by hydrogenation and equilibration in the presence of a tertiary amine . The corresponding racemic diester 6 was then subjected to hydrolysis with pig liver esterase (PLE), in the hope of achieving a kinetic resolution.…”

Section: Resultsmentioning

confidence: 99%

Enantioselective Synthesis of (−)-Pumiliotoxin C from a Chiral Amino Ester and an Acetylenic Sulfone that Acts as an Alkene Dipole Equivalent

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Nakajima

1998

J. Org. Chem.

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A new synthesis of the naturally occurring (−)-enantiomer of the dendrobatid alkaloid pumiliotoxin C (1) was achieved by the conjugate addition of methyl (−)-cis-2-amino-trans-6-methylcyclohexanecarboxylate (3) to 1-(p-toluenesulfonyl)-1-pentyne (4), followed by intramolecular acylation to afford (4aS,5R,8aR)-4a,5,6,7,8,8a-hexahydro-5-methyl-2-propyl-3-(p-toluenesulfonyl)-4-quinolinone (2). The acetylenic sulfone thus acts as the synthetic equivalent of an alkene dipole species. The required enantiopure amino ester 3 was obtained by an approach based on pig liver esterase (PLE)-mediated hydrolysis. Thus, the (−)- and (+)-enantiomers of racemic dimethyl trans-3-methylcyclohexane-cis,cis-1,2-dicarboxylate (6) afforded the corresponding half-esters 7 and 8, respectively, when treated with PLE. The desired half-ester 7 was recovered intact after selective conversion of the free carboxylic acid group of the byproduct 8 into its benzyl ester. Half-ester 7 was converted into enantiopure (−)-6 with diazomethane, followed by regioselective saponification and Curtius rearrangement to afford the required enantiopure key intermediate 3. Finally, hydrogenation of the enol triflate of enaminone 2, followed by reductive desulfonylation, afforded the product (−)-1.

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Section: Resultsmentioning

confidence: 99%

Enantioselective Synthesis of (−)-Pumiliotoxin C from a Chiral Amino Ester and an Acetylenic Sulfone that Acts as an Alkene Dipole Equivalent

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Nakajima

1998

J. Org. Chem.

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“…22,23 Como o aquecimento da piperileno sulfona (1) só produz o isômero trans, o método é satisfatoriamente empregado para este fim, fazendo uso de um inibidor radicalar como a hidroquinona, β-naftilamina, entre outros, para evitar a polimerização do piperileno, e de excesso de SO 2 em relação ao piperileno. 24 Em 2011, 25 o procedimento sintético da piperileno sulfona (1) foi otimizado e foi observado que, de acordo com a velocidade da agitação e a proporção dos reagentes, o rendimento variou de 45 a 83 %. A remoção do catalisador foi feita por extração líquido/líquido entre solução aquosa saturada de NaCl/diclorometano, um aspecto negativo do procedimento devido ao uso de solvente clorado.…”

Section: Síntese Da Piperileno Sulfonaunclassified

Piperylene Sulfone: A Smart Solvent

Rezende¹,

Silva²,

Rocha³

et al. 2014

Revista Virtual De Química

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The replacement of traditional solvents, used in chemical processes, is a real need due to environmental issues. Supercritical fluids, ionic liquids, liquefied gases, solvents and perfluorinated substances capable of undergoing structural change under controlled conditions of temperature and pressure are among the most common substitutes. Piperylene sulfone features as a polar aprotic solvent and has physicochemical properties similar to dimethylsulfoxide, and can be classified in the last group of solvents. Above 100 ºC piperylene sulfone decomposes into trans-1,3pentadiene and sulfur dioxide, which at 25 ºC produce piperylene sulfone again. This article reviews the general aspects and applications of this smart solvent.

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“…As starting material for the synthesis of 10 we used the methyl-tetrahydrophthalic anhydride 11 10) , prepared from 1,3-pentadiene and maleic anhydride. In our hands the best method for aromatization to 12 proved to be addition of Br 2 with subsequent elimination of HBr according to Newman 1 !)…”

Section: ) 3-dihydro-2-methyl-4-(4-nitrobenzoyloxymethyl)-lhisoindolmentioning

confidence: 99%

Electron Impact Induced Loss of C‐5/C‐8 Substituents of 1,2,3,4‐Tetrahydroisoquinolines, V: Synthesis and Mass Spectrometric Fragmentation of Dihydroisoindole Derivatives

Knefeli

Mayer

Wiegrebe

1989

Archiv der Pharmazie

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C-8-substituted N-methyl-l,2,3,4-tetrahydroisoquinoline radical cations lose the complete substituent in a one step reaction giving rise to an unexpected ion at m/z 146, which is probably identical with the dihydroisoindolylmethyl-cation A. The dihydroisoindoles 1, 10, and 16 were prepared as potentially alternative precursors of ion A. However, the ion at m/z 146 in their EI mass spectra is of very low intensity, so CID-experiments for structural comparison could not be performed. The electron impact induced fragmentations of 1,10, and 16 are discussed. Collision Induced Dissociation -Mass Analyzed Ion Kinetic Energy Spectroscopy . Elektronenstoß-induzierter

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cis- and trans-Piperlyenes^1,2

Cited by 50 publications

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Enantioselective Synthesis of (−)-Pumiliotoxin C from a Chiral Amino Ester and an Acetylenic Sulfone that Acts as an Alkene Dipole Equivalent

Enantioselective Synthesis of (−)-Pumiliotoxin C from a Chiral Amino Ester and an Acetylenic Sulfone that Acts as an Alkene Dipole Equivalent

Piperylene Sulfone: A Smart Solvent

Electron Impact Induced Loss of C‐5/C‐8 Substituents of 1,2,3,4‐Tetrahydroisoquinolines, V: Synthesis and Mass Spectrometric Fragmentation of Dihydroisoindole Derivatives

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cis- and trans-Piperlyenes1,2

Cited by 50 publications

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Enantioselective Synthesis of (−)-Pumiliotoxin C from a Chiral Amino Ester and an Acetylenic Sulfone that Acts as an Alkene Dipole Equivalent

Enantioselective Synthesis of (−)-Pumiliotoxin C from a Chiral Amino Ester and an Acetylenic Sulfone that Acts as an Alkene Dipole Equivalent

Piperylene Sulfone: A Smart Solvent

Electron Impact Induced Loss of C‐5/C‐8 Substituents of 1,2,3,4‐Tetrahydroisoquinolines, V: Synthesis and Mass Spectrometric Fragmentation of Dihydroisoindole Derivatives

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cis- and trans-Piperlyenes^1,2