Some Experiments Towards the Synthesis of Neoclovene

Loewenthal, H. J. E.

doi:10.1002/ijch.196600005

Cited by 6 publications

(2 citation statements)

References 7 publications

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“…Robinson annulations with five-and six-membered g-oxonitriles are remarkably regioselective 7 and considerably more efficient than annulations of the corresponding esters (Scheme 28). 134 of KCN to carvone affords the g-oxonitrile 136 as a single crystalline enantiomer, which reacts with methyl vinyl ketone to afford enone 137 without any epimerization at the nitrile stereocenter. 136 Presumably, methyl vinyl ketone approaches the intermediate enolate from the face opposite the nitrile group, which is likely in an axial orientation to avoid A 1,2 strain.…”

Section: Michael Additions Of G-oxonitrilesmentioning

confidence: 99%

Cyclic Oxonitriles: Synergistic Juxtaposition of Ketone and Nitrile Functionalities

Fleming¹,

Iyer²

2006

Synthesis

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Cyclic oxonitriles exhibit unusual regio-and chemoselectivities, reflecting the juxtaposition of electron-withdrawing ketone and nitrile functionalities. In this review, synthetic access to band g-oxonitriles is surveyed, as are the reactions of these two classes of oxonitriles. Collectively, the synopsis aims to highlight the synergistic properties of the nitrile and ketone groups by emphasizing synthetic applications which are otherwise difficult or impossible to perform.

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Section: Michael Additions Of G-oxonitrilesmentioning

confidence: 99%

Cyclic Oxonitriles: Synergistic Juxtaposition of Ketone and Nitrile Functionalities

Fleming¹,

Iyer²

2006

Synthesis

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“…100% sulfuric acid (vide infra). This product was shown to be 3,5,5-trimethyl-2-cyclopenten-1-one (8) by comparison with an authentic sample (lo), obtained as a 2:3 mixture with 3,4,4-trimethyl-2-cyclopenten-1-one (9). The individual structural assignments are based on an alternative, unambiguous synthesis of 9 (1 1) and are confirmed by comparison of the 'H nmr spectra of these compounds and 7 (Table 2).…”

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confidence: 98%

Keto ethers. IV. Products formed on reaction of dihydro-2,2,5,5-tetramethyl-3(2H)-furanone with strong acids

Yates¹,

Burke²

1987

Can. J. Chem.

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Can. J. Chem. 65, 1695Chem. 65, (1987. Reaction of tetrahydro-2,2,5,5-tetramethyl-3(2H)-furanone (1) with 96 or ca. 100% sulfuric acid or hot polyphosphoric acid followed by aqueous quenching gave the following products: 2-hydroxy-2,5-dimethyl-4-hexen-3-one (3), 2,4,4-trimethyl-2-cyclopenten-1-one (7), 3,5,5-trimethyl-2-cyclopenten-1-one (8), tetrahydro-3,4,5,5-tetramethylfuran-2,3-diol ( l l ) , 2,5-dihydro-3,5,5-trimethyl-2-methylenefuran (17) and its dimer 20, 2,5-dihydro-2,3,5,5-tetramethyl-2-furanol (IS), 4-hydroxy-2,4-dimethyl-2-pentenoic acid y-lactone (22), 2,3,5-trimethyl-2-cyclopenten-1-one (23), and tetramethylfuran (25). In 96% sulfuric acid the products arise by ring opening, ring opening followed by reclosure to carbocyclic products, methyl migration from C-2 to C-3 to give rearranged furan derivatives, and oxidation. Inca. 100% sulfuric acid or hot polyphosphoric acid further methyl migrations can occur to give 23 and 25.PETER YATES et PATRICK MICHAEL BURKE. Can. J. Chem. 65, 1695Chem. 65, (1987.La reaction de la tetrahydro tCtramCthyl-2,2,5,5 2H-furannone-3 (1) avec de I'acide sufurique a 96 ou t i environ 100% ou avec de l'acide polyphosphorique chaud, suivie par un piCgeage avec de l'eau, conduit aux produits suivants : l'hydroxy-2 dimethyl-2,5 hexkne-4 one-3 (3), la trimithyl-2,4,4 cyclopentkne-2 one-1 (7), la trimethyl-3,5,5 cyclopentkne-2 one-1 (8), le tetrahydro tCtramCthy1-3,4,5,5 furannediol-2,3 (11), le dihydro-2,5 trimethyl-3,5,5 mCthyl6ne-2 furanne (17) There have been many investigations of the reactions of organic compounds with strong acids (3, 4). Several of these have concerned substrates with saturated or unsaturated carbony1 functions. Less attention has been paid to carbonyl compounds containing other functional groups. We report on an investigation of the variety of reactions undergone by the keto ether 1 in strongly acidic media.3 We describe here the isolation and determination of the structures of the products formed in such reactions and plan, in a subsequent publication, to discuss the formation of these products in terms of the site(s) of protonation of 1 and the nature of the cationic intermediates.Compound 1 is readily available from the ynediol 2 (6). Reactions in strongly acidic media followed by aqueous quenching gave mixtures of products whose composition was dependent on both the nature of the medium and the time of reaction. These products were isolated by standard procedures and identified by their spectra (Tables 1 and 2) and by comparison in most cases with independently synthesized samples.Vapor phase chromatographic (vpc) analyses of product mixtures from 96% sulfuric acid showed that one compound was formed rapidly and that the amount of this product reached a maximum after 2 h and then fell to zero after several days. This compound was shown to be 3 by comparison with an authentic

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Mini-Violerythrine: Warum können C38-Carotinoide blau sein?

Kummer

Martin

1986

Angew. Chem.

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signifikant) groReren CI-0-Abstande im ClOC-Ion (146 und 145 pm) haben, spricht fur eine Assoziation von Kationen und Anionen. Aus dieser sicherlich nur schwachen Wechselwirkung resultiert allerdings keine Vorstufe fur symmetrische, p-oxoverbriickte Dimere, denn jedes Kation ist mit zwei Anionen (und umgekehrt) zu polymeren Verblnden verknupft. Abb. I. Stereographische Darstellung der Kristallstruktur von CI1O6. CII sowie 01 und 0 2 gehbren zu CIO:, CI2 und 0 3 -0 6 zu CIO?. Ausgewahlte Bindungslangen [pm] und -winkel ["I: CII-01 140.6(2), CII-02 141.0(2), CI2-I18.9(3), 0-CI2-0 IO8.0-110.8. 0 3 146.7(2), C12-04 143.0(2), (32-05 145.7(3), C12-06 141.7(3); 01-Cll-02 Da CI2O6 sublimierbar ist, ein Transport als Ionenpaar C10 C10 : aber unwahrscheinlich erscheint, ist fiir gasformiges C120, eine molekulare monomere oder dimere Struktur zu erwarten. Tatsachlich fanden wir, daB in der Gasphase ein gemischtes Anhydrid der Chlor-und Perchlorslure vorliegt['21. Eingegangen am 26. Juni 1986 [Z I8311 [I] a) M. Schmeisser, K. Briindle, Adu. Inorg. Chem. Radiochem. 5 (1963) 41; b) 0.

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Some Experiments Towards the Synthesis of Neoclovene

Abstract: The synthesis of compounds based on the 2,2,4, 7a‐tetramethylhydrindan system is described. Their stereochemistrry and the structures of intermediate compounds are elucidated on the basis of NMR and other spectroscopic data.

Cited by 6 publications

References 7 publications

Cyclic Oxonitriles: Synergistic Juxtaposition of Ketone and Nitrile Functionalities

Cyclic Oxonitriles: Synergistic Juxtaposition of Ketone and Nitrile Functionalities

Keto ethers. IV. Products formed on reaction of dihydro-2,2,5,5-tetramethyl-3(2H)-furanone with strong acids

Mini-Violerythrine: Warum können C38-Carotinoide blau sein?

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