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Photochemical Asymmetric Synthesis. Irradiation of Ring and Open‐chain Derivatives of L‐Erythritol 1,4‐Dicinnamate
Year:
1976
Source of publication :
Israel Journal of Chemistry
Authors :
Rejtö, Miriam
;
.
Volume :
15
Co-Authors:
Green, B.S., Departments of Structural Chemistry and Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
Hagler, A.T., Departments of Structural Chemistry and Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
Rabinsohn, Y., Departments of Structural Chemistry and Chemical Physics, Weizmann Institute of Science, Rehovot, Israel, Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, Israel
Rejtõ, M., Departments of Structural Chemistry and Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
Facilitators :
From page:
124
To page:
130
(
Total pages:
7
)
Abstract:
The two analogs, (−)‐2,3‐di‐O‐methyl‐L‐erythritol 1,4‐di‐trans‐cinnamate, 1, and (−)‐2,3‐O‐isopropylidene‐L‐erythritol 1,4‐di‐trans‐cinnamate, 2, were irradiated in benzene solution. Intramolecular 2 + 2 photocycloaddition occurs in both derivatives and the stereochemistry of the cyclobutane products, after removal of the L‐erythritol, was established in both cases as β (symmetry m)‐ and δ (symmetry 2)‐truxinate. While the asymmetric induction was 85% in the synthesis of (+)‐dimethyl δ‐truxinate from the open‐chain dimethoxy derivative 1, the more rigid isopropylidene ring derivative led to an asymmetric induction of only 6% and afforded the opposite enantioner, (−)‐dimethyl δ‐truxinate, in excess. Computer simulation of the diastereomeric ground state conformations which are believed to lead to the observed products from 1 was carried out to enable better understanding of the factors which determine the asymmetric synthesis. The simulations afford geometries and relative energies of the product precursor conformations. The results are in qualitative agreement with the experimental observations in predicting an excess of one of the two possible δ‐diastereomers. Since the geometry is also obtained by the simulation, it allows one to predict the absolute configuration of the predominant chiral product. Copyright © 1976 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
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DOI :
10.1002/ijch.197600025
Article number:
Affiliations:
Database:
Scopus
Publication Type:
article
;
.
Language:
English
Editors' remarks:
ID:
31430
Last updated date:
02/03/2022 17:27
Creation date:
17/04/2018 01:02
Scientific Publication
Photochemical Asymmetric Synthesis. Irradiation of Ring and Open‐chain Derivatives of L‐Erythritol 1,4‐Dicinnamate
15
Green, B.S., Departments of Structural Chemistry and Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
Hagler, A.T., Departments of Structural Chemistry and Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
Rabinsohn, Y., Departments of Structural Chemistry and Chemical Physics, Weizmann Institute of Science, Rehovot, Israel, Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, Israel
Rejtõ, M., Departments of Structural Chemistry and Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
Photochemical Asymmetric Synthesis. Irradiation of Ring and Open‐chain Derivatives of L‐Erythritol 1,4‐Dicinnamate
The two analogs, (−)‐2,3‐di‐O‐methyl‐L‐erythritol 1,4‐di‐trans‐cinnamate, 1, and (−)‐2,3‐O‐isopropylidene‐L‐erythritol 1,4‐di‐trans‐cinnamate, 2, were irradiated in benzene solution. Intramolecular 2 + 2 photocycloaddition occurs in both derivatives and the stereochemistry of the cyclobutane products, after removal of the L‐erythritol, was established in both cases as β (symmetry m)‐ and δ (symmetry 2)‐truxinate. While the asymmetric induction was 85% in the synthesis of (+)‐dimethyl δ‐truxinate from the open‐chain dimethoxy derivative 1, the more rigid isopropylidene ring derivative led to an asymmetric induction of only 6% and afforded the opposite enantioner, (−)‐dimethyl δ‐truxinate, in excess. Computer simulation of the diastereomeric ground state conformations which are believed to lead to the observed products from 1 was carried out to enable better understanding of the factors which determine the asymmetric synthesis. The simulations afford geometries and relative energies of the product precursor conformations. The results are in qualitative agreement with the experimental observations in predicting an excess of one of the two possible δ‐diastereomers. Since the geometry is also obtained by the simulation, it allows one to predict the absolute configuration of the predominant chiral product. Copyright © 1976 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
Scientific Publication
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