A short synthesis of (-)-chokol A

Ernst Urban; Guido Knühl; Günter Helmchen

doi:10.1016/0040-4020(95)00834-U

A short synthesis of (-)-chokol A

Ernst Urban
, Guido Knühl
, Günter Helmchen

Department of Pharmaceutical Sciences

Publications: Contribution to journal › Article › Peer Reviewed

Abstract

(-)-Chokol A (10) was prepared in six steps (22% overall yield) via conjugate addition of a higher order cyanocuprate to the chiral 2-oxo-cyclopentenecarboxylate 2n After deprotection by transesterification the enantiomerically pure β-ketoester 5 was obtained which was transformed by α-methylation and subsequent decarbethoxylation to the cyclopentanone derivative 8. Addition of methylcerium dichloride resulted in a mixture of 9a, 9b and 9c (78:16:6), from which the main diastereomer 9a was separated by MPLC. Finally desilylation of 9a achieved (-)-chokol A (10).

Original language	English
Pages (from-to)	13031-13038
Number of pages	8
Journal	Tetrahedron
Volume	51
Issue number	47
DOIs	https://doi.org/10.1016/0040-4020(95)00834-U
Publication status	Published - 20 Nov 1995

Funding

Acknowledgments: This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie. E. Urban thanks the Austrian Fonds zur Fdrderung der wissenschaftlichen Forschung for a scholarship (J0638-CHE).

Austrian Fields of Science 2012

301207 Pharmaceutical chemistry

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10.1016/0040-4020(95)00834-U

Cite this

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title = "A short synthesis of (-)-chokol A",

abstract = "(-)-Chokol A (10) was prepared in six steps (22\% overall yield) via conjugate addition of a higher order cyanocuprate to the chiral 2-oxo-cyclopentenecarboxylate 2n After deprotection by transesterification the enantiomerically pure β-ketoester 5 was obtained which was transformed by α-methylation and subsequent decarbethoxylation to the cyclopentanone derivative 8. Addition of methylcerium dichloride resulted in a mixture of 9a, 9b and 9c (78:16:6), from which the main diastereomer 9a was separated by MPLC. Finally desilylation of 9a achieved (-)-chokol A (10).",

author = "Ernst Urban and Guido Kn{\"u}hl and G{\"u}nter Helmchen",

note = "Funding Information: Acknowledgments: This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie. E. Urban thanks the Austrian Fonds zur Fdrderung der wissenschaftlichen Forschung for a scholarship (J0638-CHE).",

year = "1995",

month = nov,

day = "20",

doi = "10.1016/0040-4020(95)00834-U",

language = "English",

volume = "51",

pages = "13031--13038",

journal = "Tetrahedron",

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TY - JOUR

T1 - A short synthesis of (-)-chokol A

AU - Urban, Ernst

AU - Knühl, Guido

AU - Helmchen, Günter

N1 - Funding Information: Acknowledgments: This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie. E. Urban thanks the Austrian Fonds zur Fdrderung der wissenschaftlichen Forschung for a scholarship (J0638-CHE).

PY - 1995/11/20

Y1 - 1995/11/20

N2 - (-)-Chokol A (10) was prepared in six steps (22% overall yield) via conjugate addition of a higher order cyanocuprate to the chiral 2-oxo-cyclopentenecarboxylate 2n After deprotection by transesterification the enantiomerically pure β-ketoester 5 was obtained which was transformed by α-methylation and subsequent decarbethoxylation to the cyclopentanone derivative 8. Addition of methylcerium dichloride resulted in a mixture of 9a, 9b and 9c (78:16:6), from which the main diastereomer 9a was separated by MPLC. Finally desilylation of 9a achieved (-)-chokol A (10).

AB - (-)-Chokol A (10) was prepared in six steps (22% overall yield) via conjugate addition of a higher order cyanocuprate to the chiral 2-oxo-cyclopentenecarboxylate 2n After deprotection by transesterification the enantiomerically pure β-ketoester 5 was obtained which was transformed by α-methylation and subsequent decarbethoxylation to the cyclopentanone derivative 8. Addition of methylcerium dichloride resulted in a mixture of 9a, 9b and 9c (78:16:6), from which the main diastereomer 9a was separated by MPLC. Finally desilylation of 9a achieved (-)-chokol A (10).

UR - https://www.scopus.com/pages/publications/0028864553

U2 - 10.1016/0040-4020(95)00834-U

DO - 10.1016/0040-4020(95)00834-U

M3 - Article

AN - SCOPUS:0028864553

SN - 0040-4020

VL - 51

SP - 13031

EP - 13038

JO - Tetrahedron

JF - Tetrahedron

IS - 47

ER -

A short synthesis of (-)-chokol A

Abstract

Funding

Austrian Fields of Science 2012

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