The Absolute Configurations of Some Simple Norbornane Derivatives. A Test of the “Conformational Asymmetry” Model<sup>1a</sup>

Berson, Jerome A.; Walia, Jasjit S.; Remanick, Allen; Suzuki, Shigeto; Reynolds-Warnhoff, P.; Willner, David

doi:10.1021/ja01480a012

Cited by 113 publications

(49 citation statements)

References 3 publications

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“…rotations with those given in the literature (11). Under these One millimole of 1 and 6 mmol of c~clo~entadiene were stirred conditions 2a gave (IS, 2R, 4R) norbornan-2-carboxylic acid under nitrogen in 25 mL of the appropriate solvent and at the and 2b ( l~, 2~, 4s) norboman-2-c~boxylic acid, with optical temperature specified (Table 1).…”

Section: Wthout a Catalystmentioning

confidence: 95%

Natural amino acids as chiral auxiliaries in asymmetric Diels–Alder reactions

Bueno¹,

Cativiela²,

Mayoral³

et al. 1988

Can. J. Chem.

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M. ANDRBS. Can. J. Chem. 66, 2826Chem. 66, (1988. To test whether a-amino acids can be efficient chiral auxiliaries in asymmetric Diels-Alder reactions, the chiral dienophile N-acryloyl-L-phenylalanine methyl ester was made to react with cyclopentadiene. Diastereofacial selectivity is to a great extent dependent on the Lewis acid used to promote the reaction; whereas moderate excesses of the (1 R, 2R)-cycloadduct were achieved with AlC13, the reaction did not show diastereofacial selectivity when titanium catalysts were used. Moreover, with T~('PI-(I)4 a transesterification reaction, which leads to the isopropyl ester and competes with the Diels-Alder reaction, was observed. In spite of the structural similarity of this dienophile to the acrylate of (S)-ethyl lactate, it behaved very differently in the titanium-catalyzed reactions.MARIA P. BUENO, CARLOS CATIVIELA, JOSB A. MAYORAL, ALBERTO AVENOZA, PAULA CHARRO, MIGUEL A. ROY et Josg M. ANDRBS. Can. J. Chem. 66,2826Chem. 66, (1988.Afin de dCterminer si les acides a-aminCs peuvent Ctre des auxiliaires chiraux efficaces dans des reactions de Diels-Alder asymCtriques, on a fait rCagir le cyclopentadikne avec le diknophile chiral suivant : l'ester mCthylique de la N-acryloyl-Lphenylalanine. La sClectivitC diastCrCofaciale dCpend beaucoup de l'acide de Lewis utilisC pour promouvoir la rCaction; alors que le AlC13 nous permet d'obtenir de legers excks du cycloadduit-(lR, 2R), on n'a pas detect6 de sClectivitC diastCrCofaciale lorsqu'on a utilisC des catalyseurs de titane. De plus, avec le Ti(i-Pr0)4, on a observC une rCaction de transestCrification qui entre en competition avec la rCaction de Diels-Alder et qui conduit i la formation de l'ester isopropylique. D'un point de vue structural, ce diknophile ressemble beaucoup i l'acrylate du (S)-lactate d'Cthyle; malgrC ces ressemblances, les deux se comportent trks differemment au cours de reactions catalysees par le titane.[Traduit par la revue]High levels of diastereofacial selectivity have been achieved = 1 :6 (Scheme 1). The results of the reactions were determined in asymmetric Diels-Alder additions of prochiral 1,3-dienes to dienophiles with a removable, chiral-directing auxiliary (1). However, it is interesting to test whether chiral reagents, both enantiomers of which are inexpensive and easily available, can be efficient chiral auxiliaries in this kind of reaction. In this context, reactions of acrylates (2) and fumarates (3) of several derivatives of chiral hydroxy acids with cyclopentadiene are reported to proceed with good selectivity, mainly when TiC14 is used to promote the reaction. The results obtained are explained by the formation of a dienophile-TiC14 chelate complex, which amplifies diastereofacial discrimination (4). Also several Nacryloyl and N-crotonyl compounds, such as the N-acyloxazolidones (5) and the N-acylsultams (6) derived from camphor, have been used as chiral dienophiles.In spite of their availability, inexpensive natural a-amino acids, which have been used in a lot of asymmetric reactio...

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Section: Wthout a Catalystmentioning

confidence: 95%

Natural amino acids as chiral auxiliaries in asymmetric Diels–Alder reactions

Bueno¹,

Cativiela²,

Mayoral³

et al. 1988

Can. J. Chem.

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“…Lithium aluminium hydride reduction of the mixture gave the corresponding mixture of carbinols (33). 49 'lbsylation, followed by further reduction with lithium aluminium hydride gave the hydrocarbon camphenilene ( 34) • 4 9 EfxJxida tion with per lauric acid gave only the exo-ep::>xide 35 1 Spectral datcl and elanentc'lry analysis for previously unknown alcohol 49 were in agreanent with the proposed structure (cf. EXPERIMENTAL).…”

mentioning

confidence: 85%

Base-catalyzed protium–deuterium exchange in bicyclo[2.2.1]heptanones

Taillefer¹

1970

Can. J. Chem.

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The rates of NaOD-catalyzed protium–deuterium exo exchange in fenchan-2,5-dione (2) and 1-methyl-5-oxo-camphene (3) are 200 and 7, respectively, relative to epiisofenchone (1). The endo exchange rates in 2 and 3 are 1840 and 4, respectively, relative to 1. These data give information about the relative importances of conjugative, conformational, inductive, strain, and steric effects which may arise when a carbonyl group or a double bond is situated 1,3 to an enolizable center in the 2.2.1 system.

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“…To a t-butyl methyl ether (50 mL) solution of racemic (±)-endo-2-norborneol (44.6 mmol) and vinyl acetate (10 mL), porcine pancreatic lipase (30 g [34][35][36][37][38] ) was obtained from basic hydrolysis (0.1 M KOH) of (R)-endo-norbornyl butyrate in ethanol (95%) in 99% yield. The enantiomeric excess (e.e.)…”

Section: (S)-(-)-endo-and (R)-(+)-endo-2-norborneol (Scheme 2)mentioning

confidence: 99%

“…Duplicate sets of data were collected for each inhibitor concentration. [34][35][36][37][38] and the 19 F-NMR spectra of their Mosher's ester derivatives [39][40][41] (Table 1 and Scheme 3).…”

mentioning

confidence: 99%

Stereoselective inhibition of butyrylcholinesterase by enantiomers ofexo- andendo-2-norbornyl-N-n-butylcarbamates

Chiou

Huang

Yeh

et al. 2009

Journal of Enzyme Inhibition and Medicinal Chemistry

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The Absolute Configurations of Some Simple Norbornane Derivatives. A Test of the “Conformational Asymmetry” Model^1a

Cited by 113 publications

References 3 publications

Natural amino acids as chiral auxiliaries in asymmetric Diels–Alder reactions

Natural amino acids as chiral auxiliaries in asymmetric Diels–Alder reactions

Base-catalyzed protium–deuterium exchange in bicyclo[2.2.1]heptanones

Stereoselective inhibition of butyrylcholinesterase by enantiomers ofexo- andendo-2-norbornyl-N-n-butylcarbamates

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The Absolute Configurations of Some Simple Norbornane Derivatives. A Test of the “Conformational Asymmetry” Model1a

Cited by 113 publications

References 3 publications

Natural amino acids as chiral auxiliaries in asymmetric Diels–Alder reactions

Natural amino acids as chiral auxiliaries in asymmetric Diels–Alder reactions

Base-catalyzed protium–deuterium exchange in bicyclo[2.2.1]heptanones

Stereoselective inhibition of butyrylcholinesterase by enantiomers ofexo- andendo-2-norbornyl-N-n-butylcarbamates

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The Absolute Configurations of Some Simple Norbornane Derivatives. A Test of the “Conformational Asymmetry” Model^1a