Zur stereochemie der Reformatzky-reaktion in der norbornanon- und norbornenon-reihe

Lauria, F.; Vecchietti, Vittorio; Logemann, W.; Tosolini, Giampaolo; Dradi, E.

doi:10.1016/s0040-4020(01)82932-x

Cited by 7 publications

(4 citation statements)

References 6 publications

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“…The exo selectivities are increased by more than 10% for both diesters 4a and 4b . Interestingly, the extent of the enhancement is comparable to that observed in the addition of ethyl bromoacetate to 2-norbornenone (90% exo) versus 2-norbornanone (100% exo) in the Reformatsky reaction, even though in our selective monohydrolysis, the nucleophile, OH − , is far smaller than ethyl bromoacetate and thus may appear less influenced by the steric environment, especially in this remote position. It is also noteworthy that sodium borohydride reduction of the carbonyl of 2-norbornenone and 2-norbornanone showed slightly enhanced exo-selectivity in the reduction of 2-norbornenone (95% exo) than of 2-norbornanone (86% exo).…”

Section: Resultssupporting

confidence: 75%

Remote Exo/Endo Selectivity in Selective Monohydrolysis of Dialkyl Bicyclo[2.2.1]heptane-2,3-dicarboxylate Derivatives

et al. 2010

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High exo-facial selectivity was observed in the selective monohydrolysis of a series of near-symmetric diesters that possess an exo-ester group and an endo-ester group attached on a norbornane or norbornene skeleton. The selectivities were found to be clear-cut, although the reaction center in these reactions is one covalent bond distant from the norbornane or norbornene ring, where the difference of the environment between the exo face and endo face is therefore expected to be negligible. The effect of the co-solvent we studied earlier for the selective monohydrolysis reaction was also confirmed and contributed to improvement of the yields of the half-esters.

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Section: Resultssupporting

confidence: 75%

Remote Exo/Endo Selectivity in Selective Monohydrolysis of Dialkyl Bicyclo[2.2.1]heptane-2,3-dicarboxylate Derivatives

et al. 2010

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“…(E)-arzd (Z)-(norborn-2-ylidene (8 and 9), and the ethyl esters of the latter ( I 0 and I I ) with concentrated sulfuric ctcid. Formation of 6 Individual 5% solutions of 7 and mixtures of 8 and 9 and of 10 and 11 (3,4) in concentrated sulfuric acid were stirred without external heating for 5, ]Oh, and 6 h, respectively. The reaction mixtures were quenched with large amounts of ice-water and extracted several times with dichloromethane.…”

Section: Exo-2-hydro-rynorbomle-i -Acetic Acid Lactorze (4) ( ( 2 ) Fmentioning

confidence: 99%

“…3 We have subsequently found that with 48% hydrobromic acid at room temperature 1 gives solely the lactone of exo-2-hydroxynorbornane-1 -acetic acid '~a u r i a et al (4) report that a single diastereomer is formed; however, their product may have undergone fractionation during purification since they hydrolyzed the crude ester, crystallized the resulting acid, and then re-esterified. 3~1 1 compounds prepared in our present and previous studies in this area are racemic, but are structurally represented as single enantiomers.…”

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confidence: 99%

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Rearrangements in the acid-catalyzed formation of lactones from 2-hydroxynorbornane-2-acetic acid derivatives and related compounds

Yates¹,

Kaldas²

1992

Can. J. Chem.

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PETER YATES and MAGDY KALDAS. Can. J. Chem. 70, 2491Chem. 70, (1992. A mixture of the epimeric ethyl 2-hydroxynorbornane-2-acetates (1) on treatment with concentrated sulfuric acid is converted in tum to the lactones of exo-2-hydroxynorbomane-1-acetic acid (4), endo-6-hydroxynorbomane-endo-2-acetic acid (5), and exo-3-hydroxynorbornane-exo-2-acetic acid (6). With trifluoroacetic acid or 50% sulfuric acid, 1 gives 4, but this does not react further. In concentrated sulfuric acid the parent acids of 1 (7) and (E)-and (Z)-(norborn-2-y1idene)acetic acids (8 and 9) and their ethyl esters (10 and 11) give 6 as the infinity product. A mixture of 5-norbornene-endo-and exo-2-acetic acid (30 and 31) on treatment with 50% sulfuric acid gives 4, 5 , 6, and exo-2-hydroxynorbornane-syn-7-acetic acid lactone (33). Routes are proposed for the formation of the lactones that involve protonation and carbocation formation followed by rearrangement via Wagner-Meerwein, endo-6,2-hydride, and exo-3,2-hydride shifts in decreasing order of preference. It is postulated that the usual inhibition of the rearrangement of tertiary to secondary norbornyl carbocations is not operative when the third substituent is a carboxymethyl group or its derivatives because of the electron-withdrawing properties of such groups relative to simple alkyl groups. A preliminary study has shown that exo-5-acetyloxy-endo-2-hydroxynorbomane-exo-2-acetic acid (35) with 50% sulfuric acid gives four products that are considered to be the y-lactones of endo-5-acetyloxy-and endo-5-hydroxynorbornane-l-acetic acid (38 and 39) and exo-2-acetyloxy-1-hydroxy-and 1,2-dihydroxynorbornane-syn-7-acetic acid (40 and 41). Protonation of either the hydroxyl or acetyloxyl group is postulated, giving two carbocations that undergo rearrangements as in the case of 1, together with 3,2-hydroxyl shifts. The structures of the lactones are assigned on the basis of spectroscopy, reactivity, and analogy. The reactions of the lactones, which lead to a variety of hydroxy-and oxonorbomaneacetic acids, illustrate their synthetic potential.PETER YATES et MAGDY KALDAS. Can. J. Chem. 70, 2491Chem. 70, (1992. Un melange d'epimkres de 2-hydoxynorbornane-2-acetates d'ethyle ( I ) trait6 par de l'acide sulfurique concentre conduit aux lactones des acides exo-2-hydroxynorbornane-1-acetique (4), endo-6-hydroxynorbornane-endo-2-acetique (5) et exo-3-hydroxynorbornane-exo-2-acetique (6). Par traitement avec de l'acide trifluorbacetique ou de l'acide sulfurique a 50%, le compose 1 conduit au composC 4, mais la rCaction ne va pas plus loin. En milieu acide sulfurique concentre, les acides parents du composC 1, soit les composCs (7), les acides (E)-et (Z)-(norborn-2-ylidkne) acCtiques (8 et 9) ainsi que leurs esters Cthyliques (10 et 11) ne conduisent qu'au composC 6 comme produit obtenu aprks un temps infini. Un mClange des acides 5-norbomkne-endo-et exo-2-acCtique (30 et 31) trait6 par de l'acide sulfurique ti 50% permet d'obtenir les composCs 4, 5, 6 ainsi que la lactone de l'acide exo-2-hydroxynorbo...

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The R eformatsky Reaction

Rathke

2011

Organic Reactions

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The Reformatsky reaction is the reaction of a carbonyl compound, usually an aldehyde or a ketone, with an alpha‐haloester in the presence of zinc metal to furnish, after hydrolysis, a β‐hydoxyester. Subsequent dehydration of the hydroxyester is commonly carried out to form an alpha, β‐unsaturated ester. This chapter summarizes some of the more important advances in the understanding and use of the Reformatsky reaction since the original chapter was published in volume 1 of this series.

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Zur stereochemie der Reformatzky-reaktion in der norbornanon- und norbornenon-reihe

Cited by 7 publications

References 6 publications

Remote Exo/Endo Selectivity in Selective Monohydrolysis of Dialkyl Bicyclo[2.2.1]heptane-2,3-dicarboxylate Derivatives

Remote Exo/Endo Selectivity in Selective Monohydrolysis of Dialkyl Bicyclo[2.2.1]heptane-2,3-dicarboxylate Derivatives

Rearrangements in the acid-catalyzed formation of lactones from 2-hydroxynorbornane-2-acetic acid derivatives and related compounds

The R eformatsky Reaction

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