On the Titrimetric Determination of the Configuration of Bridged Diels-Alder Adducts<sup>1a</sup>

Stockmann, Hans

doi:10.1021/jo01065a084

Cited by 38 publications

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“…As has been pointed out by Martin and Hill in their review of the stereochemistry of the ,The system which we have adopted to define stereochemistry in 2 is that originally used by Stockman (17), in which the relationship of the ring-juncture substituents to the two bridged rings are denoted, reading from left to right. We have used this system also to define the stereochemistry of 3 (and the triadducts l l ) , where the ring-juncture substituents are hydrogen atoms.…”

Section: Introductionmentioning

confidence: 99%

Influence of Lewis Acids on the Diels–Alder Reaction. V. The Reaction of Furan with Dimethyl Acetylenedicarboxylate

Mcculloch¹,

Smith²,

McInnes³

1973

Can. J. Chem.

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The Diels-Alder addition of furan to dimethyl acetylenedicarboxylate (DMAD) affords a monoadduct 1. The position and steric course of further addition of furan to the latter are temperature dependent. At temperatures of 50" or below addition occurs mainly at the activated double bond to give et~do-endo 4 and endo-exo 5 diadducts. At 100" addition occurs at the less substituted double bond of the monoadduct to give analogous etrdo-endo 7 and endo-exo 9 diadducts; further addition of furan to the latter at 100' affords four triadducts 12-15. The configurations of all these products were determined by p.m.r. and assignments confirmed by simulation of the spectra.AICI, causes enormous rate enhancement of the Diels-Alder additions of furan to DMAD and to the activated double bond of the monoadduct. In the presence of the Lewis acid the predominant diadduct formed is the endo-exo isomer 5.L'addition du type Diels-Alder du furanne sur I'acCtylenedicarboxylate de dimithyle (DMAD) conduit au produit de monoaddition 1. La positio~l et le mecanisme sterique d'additions supplCmentaires du furanne sur le produit 1 dependent de la temperature. A 50 "C ou en-dessous I'addition se produit principalement sur la double liaison activee pour donner des produits de double addition endo-endo 4 et endo-exo 5. A 100 "C, I'addition se produit sur la double liaison la moins substituie du produit de monoaddition pour donner les produits de double addition analogues et~do-endo 7 et endo-exo 9; des additions supplCmentaires du furanne sur ces derniers produits a 100 "C conduisent a quatre produits de triple addition 12-15. Les configurations de tous ces produits ont CtC dCterminCes par r.m.n. e t les attributions ont CtC confirmkes par simulation des spectres.Le AICI, entraine une augmentation enorme de la vitesse d'addition du type Diels-Alder du furanne sur le DMAD et sur la double liaison activke du oroduit de monoaddition. En oresence de I'acide deLewis. Ie produit majeur de double addition form6 est l'isomkre etldo-e.ro 5.

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Section: Introductionmentioning

confidence: 99%

Influence of Lewis Acids on the Diels–Alder Reaction. V. The Reaction of Furan with Dimethyl Acetylenedicarboxylate

Mcculloch¹,

Smith²,

McInnes³

1973

Can. J. Chem.

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“…Several chemical methods have been employed to establish the configuration of Diels-Alder adducts (4). Lactonization (5), iodolactonization ( G ) , and titrimetric analysis (4) have been used for this purpose with carboxylic acid derivatives of bicyclo[2.2.l]hept-2-ene. The first two suffer the disadvantage that rearrangements do occur under the reaction conditions.…”

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confidence: 99%

The Establishment of Configuration in Diels–alder Adducts by N.M.R. Spectroscopy

Fraser¹

1962

Can. J. Chem.

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It has been shown that the ~nag~letically anisotropic double bond in bicyclic Diels-Alder adducts exerts a paramagnetic effect on protons in an ezo config~~ratio~l and a diamagnetic effect on protons in an endo configuration. Thus the configuration of a proton or protonbearing substituent can be ascertained by observing the change in its chemical shift when the double bond is removed by hydrogenation. However, caution nus st be used in applying the method to compounds in which the double bond bears a magnetically anisotropic substituent.The Diels-Alder reaction between cyclic dienes and derivatives of ethylene inay produce either of two diastereomeric adducts, the endo or the exo isomer. In nlost instances the endo isomer predominates in accordance with Alder's rule (I). However, exceptions to this rule have been observed (2, 3) so that each new adduct synthesized requires proof of its stereochemistry. Several chemical methods have been employed to establish the configuration of Diels-Alder adducts (4). Lactonization (5), iodolactonization ( G ) , and titrimetric analysis (4) have been used for this purpose with carboxylic acid derivatives of bicyclo[2.2.l]hept-2-ene. The first two suffer the disadvantage that rearrangements do occur under the reaction conditions. Classical degradative procedures (7) are often unambiguous but exceedingly arduous.The use of physical methods obviates both of these difficulties. Alder and co-workers (3) have employed infrared spectroscopy to assign configurations to the two 5-cyanobicyclo[2.2.2]oct-2-enes forined from cyclohexadiene and acrylonitrile. Nuclear nlagnetic resonance has already proved itself capable of differentiating between diastereoisomers in cyclol~exanes (8) and cyclopentanes (9) and between geonletrical isomers ill inany olefin derivatives (10, 11). I t therefore seeined worth while to investigate the ability of n.nl.r. to be used in assigning structures t o diastereomeric Diels-Alder adducts.I t has already been found that in the cai11phane-2,3-diols (12), in a and a' chlorocainphor (13), and in 3,8-c~~clocampl1or (14) the inagnitude of the coupling of a n exo proton with the adjacent bridgehead proton is larger (4-5 cycles/sec) than when the proton is endo (0-1 cycles/sec). Thus when such a proton is well separated fro111 the rest of the absorption pattern, the size of its spin-spin interaction with the bridgehead proton will establish the configuration of the compound. A inore general method would be possible if the chemical shift of a proton could be correlated with its endo or exo position. T o explore this possibility we have exanlined the spectra of five derivatives of bic~~clo[2.2.l]hept-2-ene whose configurations had been previously established (22).These are the two diastereoineric adducts of a-methacrylic acid and c>-clopentadiene, the two adducts of trans-crotonic acid and cyclope~itadiene, and the eso aclduct of methyl methacrylate and cyclopentadiene. After reilloval of the double bond by hydrogenation, the spectra of the five dihydrocoinpou...

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“…7 Subsequently, Stockman claimed, based upon iodometric titration, that the product was a mixture of the exo-exo-1 and exo-endo-6 isomers, with the latter composing 91% of the mixture, in disagreement with the previous findings. 8 Scheme 1 The 2 × [4+2] cycloaddition of acetylene dicarboxylic acid and furan with possible stereoisomers 1, 6, and 7…”

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Solid-State Structure of Some Substituted Hexahydro-1,4:5,8-diepoxynaphthalenes

Masters¹,

Nieger

Bräse³

2011

Synlett

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On the Titrimetric Determination of the Configuration of Bridged Diels-Alder Adducts^1a

Cited by 38 publications

References 0 publications

Influence of Lewis Acids on the Diels–Alder Reaction. V. The Reaction of Furan with Dimethyl Acetylenedicarboxylate

Influence of Lewis Acids on the Diels–Alder Reaction. V. The Reaction of Furan with Dimethyl Acetylenedicarboxylate

The Establishment of Configuration in Diels–alder Adducts by N.M.R. Spectroscopy

Solid-State Structure of Some Substituted Hexahydro-1,4:5,8-diepoxynaphthalenes

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On the Titrimetric Determination of the Configuration of Bridged Diels-Alder Adducts1a

Cited by 38 publications

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Influence of Lewis Acids on the Diels–Alder Reaction. V. The Reaction of Furan with Dimethyl Acetylenedicarboxylate

Influence of Lewis Acids on the Diels–Alder Reaction. V. The Reaction of Furan with Dimethyl Acetylenedicarboxylate

The Establishment of Configuration in Diels–alder Adducts by N.M.R. Spectroscopy

Solid-State Structure of Some Substituted Hexahydro-1,4:5,8-diepoxy­naphthalenes

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On the Titrimetric Determination of the Configuration of Bridged Diels-Alder Adducts^1a

Solid-State Structure of Some Substituted Hexahydro-1,4:5,8-diepoxynaphthalenes