A new β-acyl vinyl anion equivalent. Synthesis of pyrenophorin

Bakuzis, Peter; BAKUZIS, M. L. F.; WEINGARTNER, T. F.

doi:10.1016/s0040-4039(01)94777-x

Cited by 67 publications

(15 citation statements)

References 22 publications

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“…Both signals confirm that the organic groups were covalently bonded onto the silica surface. The other two peaks are attributed to pure surface signals described as: i) Si(OSi) 4 , Q 4 at -104 ppm; ii) surface signal, Si(OSi) 3 OH, Q 3 at -96 ppm. 19,23 Important information about immobilization of pendant groups on the inorganic structure of the catalyst can be obtained through solid state 13 C NMR spectra, as presented in Figure 4.…”

Section: Synthesis and Characterization Of The Catalystmentioning

confidence: 99%

“…The relatively high acidity of the nitro group and its facile transformation into various functionalities have extended the importance of nitro compounds and these have proven to be valuable intermediates for the preparation of complex molecules [1][2][3][4][5] and to serve as precursors, extensively used in the agrochemical, pharmaceutical and dyestuff industries. 6 Thus, a great interest in these kinds of synthetic processes has been shown in recent years.…”

Section: Introductionmentioning

confidence: 99%

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Tetramethylguanidine covalently bonded onto silica gel as catalyst for the addition of nitromethane to cyclopentenone

Oliveira¹,

Torres²,

Silva³

et al. 2006

J. Braz. Chem. Soc.

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Um catalisador baseado em sílica quimicamente modificada com tetrametilguanidina (TMG) foi sintetizado pela co-condensação de tetraetilortossilicato (TEOS) com um novo agente sililante, preparado pela reação entre a molécula TMG e (3-cloropropil)trimetoxisilano. O direcionador n-dodecilamina foi utilizado para organizar a polimerização do catalisador inorgânico-orgânico. A termogravimetria mostrou que o número de sítios ativos do catalisador foi de 1,35 mmol g .A espectroscopia na região do infravermelho e de ressonância magnética nuclear no estado sólido para os núcleos 29 Si e 13 C confirmou a obtenção do produto desejado. Este material foi usado para catalisar a adição de nitrometano em ciclopentenona. 98% de conversão foi observada depois de 3 h de reação. O catalisador foi recuperado e reutilizado por mais catorze vezes, mantendo uma eficiência catalítica em torno de 98%.A catalyst based on silica chemically modified with tetramethylguanidine (TMG) was synthesized by the co-condensation of tetraethylorthosilicate (TEOS) with a new silylant agent derived from the reaction between the TMG molecule and (3-chloropropyl)trimethoxysilane. A neutral n-dodecylamine template was used to organize the polymerization of the inorganicorganic catalyst. Thermogravimetry showed that the number of active pendant groups in the catalyst was 1.35 mmol g -1 , with a surface area of 811 ± 75 m 2 g -1. Infrared spectroscopy and 13 C and 29 Si nuclear magnetic resonance data are in agreement with the proposed structure. This material has been used to catalyse the addition of nitromethane to cyclopentenone. The catalytic efficiency was followed and the nitromethylcyclopentanone conversion presented a yield of 98% at 3 h of reaction. The catalyst was recovered and reused 14 times, maintaining about 98% of its catalytic efficiency.

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Section: Synthesis and Characterization Of The Catalystmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tetramethylguanidine covalently bonded onto silica gel as catalyst for the addition of nitromethane to cyclopentenone

Oliveira¹,

Torres²,

Silva³

et al. 2006

J. Braz. Chem. Soc.

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“…After filtering through silicagel (2 g), the filtrate was washed thrice with 0.5 N HCI and once with sodium hydrogen carbonate solution; then was dried with MgSO, and the solvent was removed under reduced pressure to yield an oily residue (35). 59 (17). 55 (I@, 43 (21), 41 (14).…”

Section: -(4-tert-butyldimethylsiloxy-i-oxopent~l)-22-dimethyltetramentioning

confidence: 99%

A Short Synthesis of (R,R)‐(‐)‐Pyrenophorin from (S)‐Propylene Oxide and a 3‐Pentenoic Acid d⁵‐Reagent

Mali¹,

Pohmakotr²,

Weidmann³

et al. 1981

Liebigs Ann. Chem.

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Analysis of the known syntheses of pyrenophorin (1) (Scheme 1) reveals that they all rest upon the use of reagents with di-, d3-, or a'-reactivity umpolung for the establishment of at least one of the 1,4-distances of functional groups. A different approach, outlined in Scheme 2, has now been realized: the non-conjugated and the conjugated 7-hydroxyoctenoic acids 10 and 11, obtained from dienone dianion derivatives of type 3 and d,l-or (S)-methyloxirane, are converted to the macrodiolides 12 and 13, respectively. These are directly oxidized with introduction of an oxygen function at position 4, see 13 + 1 and 12 + 16 + 17 + 1. The overall transformation of the 7.6-unsaturated ketone 18 to pyrenophorin (1) in 27% yield takes six steps, partly without purification of intermediates. Eine kurze Synthese von (R,R)-( -)-Pyrenophorin aus (S)-Propylenoxid und einem3-Pentensaure-d5-Reagenz 1, 2, Eine Analyse der bisher bekannten Synthesen von Pyrenophorin (l), siehe Schema 1 , zeigt, daR wenigstens einer der 1,4-Abstande funktioneller Gruppen durch Verwendung eines umgepolten Reagenzes (d', d3,az) zustande kommt. Es wird ein neuer, in Schema 2 skizzierter Weg beschrieben: Aus Dienondianion-Derivaten vom Typ 3 und d,i-oder (S)-Methyloxiran entstehen die VorIaufer 10 und 11 der noch nicht vollstandig funktionalisierten Makrodiolide 12 bzw. 13; aus diesen erhalt man durch 1,4-Oxidation Pyrenophorin (l), siehe 13 + 1 und 12-16 + 17 --* 1. Die Reaktionsfolge vom y,S-ungesattigten Keton 18 zu Pyrenophorin (1) besteht aus sechs Schritten, die -Zuni Teil ohne Reinigung der Zwischenprodukte -in 27proz. Gesamtausbeute durchgefiihrt werden.The simple macrodiolides c~l l e t o d i o l~~~) , grahamimycin Al ' ), pyrenophorin lo), vermiculine "), elaiophylin 12), and pyrenophorol 13) have attracted synthetic chemists' attention and rigorous efforts have been made to discover new synthetic routes leading t o this group of compounds. Thus, we are aware of thirteeni4-22,43) and five'5,23-25*43) different syntheses of the symmetrical molecules pyrenophorin (1) and vermiculine (2), respectively.

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“…Treatment of the aldehyde 41 with nitroalkane 38 and diisopropylamine in dimethylformamide (23), at room temperature for 3 h, afforded the adduct 42, presumably as a mixture of diastereomers, in good yield.…”

Section: Ch2=ch2 + Ch3coci a Rachmentioning

confidence: 99%

“…Acetylation provided acetate 35. The structures of 34 and 35 were established by nmr only, but gave us confidence to proceed with a more elaborate nitroalkane 38, which was prepared by an adaptation of the sequence described by Bakuzis et al (23). The procedure consisted of treating acetyl chloride with ethylene and aluminum trichloride to give 1-chloro-3-butanone, and hence to the corresponding ketal38.…”

mentioning

confidence: 99%

Oxidation products of arachidonic acid. IV. Model studies on the attachaient of the C(13)—C(20) side-chain in the synthesis of tetrahydrofurans and pyrans 1,2, and 3

Just¹,

Crosilla²

1980

Can. J. Chem.

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GEORGE JUST and DANILO CROSILLA. Can. J. Chem. 58, 2349Chem. 58, (1980 The synthesis of methyl 15-hydroxy-8(R)-methoxy-11(R)-p-nitrobenzoyloxy-9(S),12(R)-oxy-eicosa-13-ynoate, an arachidonic acid metabolite derivative, is described. As well, methods for the attachment of the C ( 1 3 j C ( 2 0 ) prostaglandin side-chain to furanosides were studied and the results are described. The reduction of the C-15 keto group on a model compound was performed and was found to have the same behavior as in the prostaglandins.A partial structure proof of Pace-Asciak's compound, 9,12-oxy-8,11,15-trihydroxy-13-enoic acid is given.GEORGE JUST et DANILO CROSILLA. Can. J. Chem. 58,2349Chem. 58, (1980. On decrit la synthkse de I'hydroxy-15 methoxy-8(R) p-nitrobenzoyloxy-ll(R) oxy-9(S), 12(R) eicosyne-13 oate de mtthyle, un derive metabolique de I'acide arachidonique. On a egalement etudie les methodes de fixation des carbones en position 13 i 20 de la chaine laterale de la prostaglandine aux furannosides et on decrit les resultats. On a realist la reduction du groupe cetonique en position 15 sur un compose type et on a trouve qu'il se comporte comme celui des prostaglandines. On donne une preuve partielle de structure du compose de Pace-Asciak, I'acide oxy-9,12 trihydroxy-8,11,15 kne-13 oique.[Traduit par le journal]In connection with the synthesis of oxidation products of arachidonic acid of type 1, 2, and 3, isolated by Pace-Asciak and Wolfe (1) and Axelrod and co-workers (2), we had to work out procedures for attaching the C(13)-C (20) side-chain to furanose derivatives (for rationale of the choice of stereochemistry of the model compounds, see refs. 1,3). In this paper, we wish to describe some model studies on this attachment and the synthesis of a derivative of type 1 having an acetylenic bond at A13, which strongly supports the structure assigned to 1.As a model, we used 1,2-0-isopropylidene-3,5,6-tri-0-methyl-a-D-glucofuranose (5); which is easily obtained by methylation (4) of the commercially available glucofuranose 4. Hydrolysis of 5 with hydrochloric acid, followed by acetylation with p-nitrobenzoyl chloride in pyridine (5) gave 7 as a mixture of anomers. Treatment with hydrogen bromide in benzene at 0°C (6) transformed 7 to bromides 8, which, when submitted to the action of mercuric cyanide in nitromethane (6), gave the Pcyanide 9 as one isomer only, as established by nmr which showed the C(l) hydrogen as a broad singlet (J,,, 2 0-1) indicating a HI,,-dihedral angle of approximately 90°C. Alkaline hydrolysis gave the cyano alcohol

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A new β-acyl vinyl anion equivalent. Synthesis of pyrenophorin

Cited by 67 publications

References 22 publications

Tetramethylguanidine covalently bonded onto silica gel as catalyst for the addition of nitromethane to cyclopentenone

Tetramethylguanidine covalently bonded onto silica gel as catalyst for the addition of nitromethane to cyclopentenone

A Short Synthesis of (R,R)‐(‐)‐Pyrenophorin from (S)‐Propylene Oxide and a 3‐Pentenoic Acid d⁵‐Reagent

Oxidation products of arachidonic acid. IV. Model studies on the attachaient of the C(13)—C(20) side-chain in the synthesis of tetrahydrofurans and pyrans 1,2, and 3

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A new β-acyl vinyl anion equivalent. Synthesis of pyrenophorin

Cited by 67 publications

References 22 publications

Tetramethylguanidine covalently bonded onto silica gel as catalyst for the addition of nitromethane to cyclopentenone

Tetramethylguanidine covalently bonded onto silica gel as catalyst for the addition of nitromethane to cyclopentenone

A Short Synthesis of (R,R)‐(‐)‐Pyrenophorin from (S)‐Propylene Oxide and a 3‐Pentenoic Acid d5‐Reagent

Oxidation products of arachidonic acid. IV. Model studies on the attachaient of the C(13)—C(20) side-chain in the synthesis of tetrahydrofurans and pyrans 1,2, and 3

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A Short Synthesis of (R,R)‐(‐)‐Pyrenophorin from (S)‐Propylene Oxide and a 3‐Pentenoic Acid d⁵‐Reagent