Stereochemistry of a Spherand-Type Calixarene

K. Agbaria; S.E. Biali; V. Bohmer; J. Brenn; S. Cohen; M. Frings; F. Grynszpan; J.M. Harrowfield; Alexandre Sobolev; I. Thondorf

doi:10.1021/jo0016576

Stereochemistry of a Spherand-Type Calixarene

K. Agbaria, S.E. Biali, V. Bohmer, J. Brenn, S. Cohen, M. Frings, F. Grynszpan, J.M. Harrowfield, Alexandre Sobolev, I. Thondorf

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Abstract

The stereochemistry of the spherand-type calixarene 2a is analyzed in terms of the configuration of the three 2,2 ' -dihydroxybiphenyl subunits (R or S) and the disposition of the methylene groups (crown or twist). X-ray crystallography indicates that the neutral as and its mono- or dianion (in form of the salts 2a(-).C5H5NH+ and 2a(2-). 2Et(3)NH(+)) exist essentially in the same conformation (RRS/SSR-twist). This asymmetric RRS/SSR-twist form is the lowest energy conformer according to molecular mechanics calculations. Low-temperature H-1 NMR data indicate the presence of a major conformer of C-1 symmetry, in agreement with a RRS/SSR-twist form. The lowest energy topomerization pathway mutually exchanges two pairs of methylene protons and is ascribed to an enantiomerization process involving rotation around an Ar-Ar bond.

Original language	English
Pages (from-to)	2900-2906
Journal	Journal of Organic Chemistry
Volume	66
DOIs	https://doi.org/10.1021/jo0016576
Publication status	Published - 2001

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@article{5f98484e4f72431bb61f46d76be18b9c,

title = "Stereochemistry of a Spherand-Type Calixarene",

abstract = "The stereochemistry of the spherand-type calixarene 2a is analyzed in terms of the configuration of the three 2,2 ' -dihydroxybiphenyl subunits (R or S) and the disposition of the methylene groups (crown or twist). X-ray crystallography indicates that the neutral as and its mono- or dianion (in form of the salts 2a(-).C5H5NH+ and 2a(2-). 2Et(3)NH(+)) exist essentially in the same conformation (RRS/SSR-twist). This asymmetric RRS/SSR-twist form is the lowest energy conformer according to molecular mechanics calculations. Low-temperature H-1 NMR data indicate the presence of a major conformer of C-1 symmetry, in agreement with a RRS/SSR-twist form. The lowest energy topomerization pathway mutually exchanges two pairs of methylene protons and is ascribed to an enantiomerization process involving rotation around an Ar-Ar bond.",

author = "K. Agbaria and S.E. Biali and V. Bohmer and J. Brenn and S. Cohen and M. Frings and F. Grynszpan and J.M. Harrowfield and Alexandre Sobolev and I. Thondorf",

year = "2001",

doi = "10.1021/jo0016576",

language = "English",

volume = "66",

pages = "2900--2906",

journal = "Journal of Organic Chemistry",

issn = "0022-3263",

publisher = "American Chemical Society",

}

TY - JOUR

T1 - Stereochemistry of a Spherand-Type Calixarene

AU - Agbaria, K.

AU - Biali, S.E.

AU - Bohmer, V.

AU - Brenn, J.

AU - Cohen, S.

AU - Frings, M.

AU - Grynszpan, F.

AU - Harrowfield, J.M.

AU - Sobolev, Alexandre

AU - Thondorf, I.

PY - 2001

Y1 - 2001

N2 - The stereochemistry of the spherand-type calixarene 2a is analyzed in terms of the configuration of the three 2,2 ' -dihydroxybiphenyl subunits (R or S) and the disposition of the methylene groups (crown or twist). X-ray crystallography indicates that the neutral as and its mono- or dianion (in form of the salts 2a(-).C5H5NH+ and 2a(2-). 2Et(3)NH(+)) exist essentially in the same conformation (RRS/SSR-twist). This asymmetric RRS/SSR-twist form is the lowest energy conformer according to molecular mechanics calculations. Low-temperature H-1 NMR data indicate the presence of a major conformer of C-1 symmetry, in agreement with a RRS/SSR-twist form. The lowest energy topomerization pathway mutually exchanges two pairs of methylene protons and is ascribed to an enantiomerization process involving rotation around an Ar-Ar bond.

AB - The stereochemistry of the spherand-type calixarene 2a is analyzed in terms of the configuration of the three 2,2 ' -dihydroxybiphenyl subunits (R or S) and the disposition of the methylene groups (crown or twist). X-ray crystallography indicates that the neutral as and its mono- or dianion (in form of the salts 2a(-).C5H5NH+ and 2a(2-). 2Et(3)NH(+)) exist essentially in the same conformation (RRS/SSR-twist). This asymmetric RRS/SSR-twist form is the lowest energy conformer according to molecular mechanics calculations. Low-temperature H-1 NMR data indicate the presence of a major conformer of C-1 symmetry, in agreement with a RRS/SSR-twist form. The lowest energy topomerization pathway mutually exchanges two pairs of methylene protons and is ascribed to an enantiomerization process involving rotation around an Ar-Ar bond.

U2 - 10.1021/jo0016576

DO - 10.1021/jo0016576

M3 - Article

SN - 0022-3263

VL - 66

SP - 2900

EP - 2906

JO - Journal of Organic Chemistry

JF - Journal of Organic Chemistry

ER -

Stereochemistry of a Spherand-Type Calixarene

Abstract

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