Stereoselective synthesis of spiro and condensed pyrazolines of steroidal α,β-unsaturated ketones and nitrilimines by 1,3-dipolar cycloaddition

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Abstract

Effective syntheses of endo- and exocyclic α,β-unsaturated ketones as C{double bond, long}C dipolarophiles were carried out in the 13α-estrone series. The 1,3-dipolar cycloadditions of 15,16α,β-unsaturated ketones of 13α-estrone 3-methyl and 3-benzyl ether with nitrilimines stereoselectively furnished two regioisomers of new condensed pyrazolines in a ratio of 2:1. The main product was the isomer obtained by the attack of the N-terminus of the 1,3-dipole on the carbon atom β to the carbonyl group of the dipolarophile. The nitrilimine cycloadditions to the 16-methylene-17-ketones of 13α-estrone 3-methyl and 3-benzyl ether stereo- and regioselectively furnished spiropyrazolines. The attack of the N-terminus of the dipole occurred on the α-carbon of the α,β-unsaturated ketones. The reactions were performed under both homogeneous and heterogeneous conditions. Silver acetate as a base proved more effective than its triethylamine counterpart. Changes in regio- and stereoselectivities were not observed on variation of the conditions of the cycloaddition reactions. The structures of the new products were determined by NMR (one- and two-dimensional) and MALDI TOF MS techniques, with C70 fullerenes as matrix in the latter case.

Original languageEnglish
Pages (from-to)520-525
Number of pages6
JournalSteroids
Volume74
Issue number6
DOIs
Publication statusPublished - Jun 2009

Fingerprint

Cycloaddition
Cycloaddition Reaction
Ketones
Estrone
Ether
Carbon
Stereoselectivity
Regioselectivity
Matrix-Assisted Laser Desorption-Ionization Mass Spectrometry
Isomers
Nuclear magnetic resonance
Atoms

Keywords

  • C fullerenes
  • Cycloadditions
  • MALDI
  • Nitrilimines
  • Pyrazolines

ASJC Scopus subject areas

  • Biochemistry
  • Clinical Biochemistry
  • Endocrinology
  • Molecular Biology
  • Organic Chemistry
  • Pharmacology

Cite this

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title = "Stereoselective synthesis of spiro and condensed pyrazolines of steroidal α,β-unsaturated ketones and nitrilimines by 1,3-dipolar cycloaddition",
abstract = "Effective syntheses of endo- and exocyclic α,β-unsaturated ketones as C{double bond, long}C dipolarophiles were carried out in the 13α-estrone series. The 1,3-dipolar cycloadditions of 15,16α,β-unsaturated ketones of 13α-estrone 3-methyl and 3-benzyl ether with nitrilimines stereoselectively furnished two regioisomers of new condensed pyrazolines in a ratio of 2:1. The main product was the isomer obtained by the attack of the N-terminus of the 1,3-dipole on the carbon atom β to the carbonyl group of the dipolarophile. The nitrilimine cycloadditions to the 16-methylene-17-ketones of 13α-estrone 3-methyl and 3-benzyl ether stereo- and regioselectively furnished spiropyrazolines. The attack of the N-terminus of the dipole occurred on the α-carbon of the α,β-unsaturated ketones. The reactions were performed under both homogeneous and heterogeneous conditions. Silver acetate as a base proved more effective than its triethylamine counterpart. Changes in regio- and stereoselectivities were not observed on variation of the conditions of the cycloaddition reactions. The structures of the new products were determined by NMR (one- and two-dimensional) and MALDI TOF MS techniques, with C70 fullerenes as matrix in the latter case.",
keywords = "C fullerenes, Cycloadditions, MALDI, Nitrilimines, Pyrazolines",
author = "E. Merny{\'a}k and Eszter Kozma and A. Het{\'e}nyi and L. M{\'a}rk and G. Schneider and J. W{\"o}lfling",
year = "2009",
month = "6",
doi = "10.1016/j.steroids.2009.02.001",
language = "English",
volume = "74",
pages = "520--525",
journal = "Steroids",
issn = "0039-128X",
publisher = "Elsevier Inc.",
number = "6",

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TY - JOUR

T1 - Stereoselective synthesis of spiro and condensed pyrazolines of steroidal α,β-unsaturated ketones and nitrilimines by 1,3-dipolar cycloaddition

AU - Mernyák, E.

AU - Kozma, Eszter

AU - Hetényi, A.

AU - Márk, L.

AU - Schneider, G.

AU - Wölfling, J.

PY - 2009/6

Y1 - 2009/6

N2 - Effective syntheses of endo- and exocyclic α,β-unsaturated ketones as C{double bond, long}C dipolarophiles were carried out in the 13α-estrone series. The 1,3-dipolar cycloadditions of 15,16α,β-unsaturated ketones of 13α-estrone 3-methyl and 3-benzyl ether with nitrilimines stereoselectively furnished two regioisomers of new condensed pyrazolines in a ratio of 2:1. The main product was the isomer obtained by the attack of the N-terminus of the 1,3-dipole on the carbon atom β to the carbonyl group of the dipolarophile. The nitrilimine cycloadditions to the 16-methylene-17-ketones of 13α-estrone 3-methyl and 3-benzyl ether stereo- and regioselectively furnished spiropyrazolines. The attack of the N-terminus of the dipole occurred on the α-carbon of the α,β-unsaturated ketones. The reactions were performed under both homogeneous and heterogeneous conditions. Silver acetate as a base proved more effective than its triethylamine counterpart. Changes in regio- and stereoselectivities were not observed on variation of the conditions of the cycloaddition reactions. The structures of the new products were determined by NMR (one- and two-dimensional) and MALDI TOF MS techniques, with C70 fullerenes as matrix in the latter case.

AB - Effective syntheses of endo- and exocyclic α,β-unsaturated ketones as C{double bond, long}C dipolarophiles were carried out in the 13α-estrone series. The 1,3-dipolar cycloadditions of 15,16α,β-unsaturated ketones of 13α-estrone 3-methyl and 3-benzyl ether with nitrilimines stereoselectively furnished two regioisomers of new condensed pyrazolines in a ratio of 2:1. The main product was the isomer obtained by the attack of the N-terminus of the 1,3-dipole on the carbon atom β to the carbonyl group of the dipolarophile. The nitrilimine cycloadditions to the 16-methylene-17-ketones of 13α-estrone 3-methyl and 3-benzyl ether stereo- and regioselectively furnished spiropyrazolines. The attack of the N-terminus of the dipole occurred on the α-carbon of the α,β-unsaturated ketones. The reactions were performed under both homogeneous and heterogeneous conditions. Silver acetate as a base proved more effective than its triethylamine counterpart. Changes in regio- and stereoselectivities were not observed on variation of the conditions of the cycloaddition reactions. The structures of the new products were determined by NMR (one- and two-dimensional) and MALDI TOF MS techniques, with C70 fullerenes as matrix in the latter case.

KW - C fullerenes

KW - Cycloadditions

KW - MALDI

KW - Nitrilimines

KW - Pyrazolines

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U2 - 10.1016/j.steroids.2009.02.001

DO - 10.1016/j.steroids.2009.02.001

M3 - Article

C2 - 19428440

AN - SCOPUS:62349093297

VL - 74

SP - 520

EP - 525

JO - Steroids

JF - Steroids

SN - 0039-128X

IS - 6

ER -