An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride

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Title:An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride
Creators:
Klinotová, Eva
Křeček, Václav
Klinot, Jiří
Buděšínský, Miloš
Podlaha, Jaroslav
Podlahová, Jana
Ječný, Jiří
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 56, 12, pp. 2917-2935

Abstract

3β-Acetoxy-21,22-dioxo-18α,19β<i>H</i>-ursan-28,20β-olide (<i>IIIa</i>) reacts with acetic anhydride in pyridine under very mild conditions affording β-lactone <i>IVa</i> and γ-lactones <i>Va</i> and <i>VIIa</i> as condensation products. On reaction with pyridine, lactones <i>Va</i> and <i>VIIa</i> undergo elimination of acetic acid to give unsaturated lactones <i>VIIIa</i> and <i>IXa</i>, respectively. Similarly, the condensation of 20β,28-epoxy-21,22-dioxo-18α,19β<i>H</i>-ursan-3β-yl acetate (<i>IIIb</i>) with acetic anhydride leads to β-lactone <i>IVb</i> and γ-lactone <i>Vb</i>; the latter on heating with pyridine affords unsaturated lactone <i>VIIIb</i> and 21-methylene-22-ketone <i>Xb</i>. The structure of the obtained compounds was derived using spectral methods, particularly <sup>1</sup>H and <sup>13</sup>C NMR spectroscopy; structure of lactone <i>IVa</i> was confirmed by X-ray diffraction.

Title:An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride
Creators:
Klinotová, Eva
Křeček, Václav
Klinot, Jiří
Buděšínský, Miloš
Podlaha, Jaroslav
Podlahová, Jana
Ječný, Jiří
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:56
Number:12
Page Range:pp. 2917-2935
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19912917UNSPECIFIED
ID Code:5198
Item Type:Article
Deposited On:22 Feb 2010 11:32
Last Modified:22 Feb 2010 10:33

Citation

Klinotová, Eva; Křeček, Václav; Klinot, Jiří; Buděšínský, Miloš; Podlaha, Jaroslav; Podlahová, Jana; Ječný, Jiří (1991) An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride. Collection of Czechoslovak Chemical Communications, 56 (12). pp. 2917-2935. ISSN 0010-0765

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