EUDESMANE SESQUITERPENES FROM EUPATORIUM QUADRANGULARE
The aerial part of Eupatorium quadrangulare afforded in addition to known compounds, a possible biosynthetic intermediate quadrangulin A, of the eudesmanolides found in this species. Key Word Index - Eupatorium quadrangulare; Compositae; sesquiterpene lactones; eudesmanolides.
Gonzalez, Antonio G.,Barrera, Jaime Bermejo,Hernandez, Angel C. Janes,Rosas, Francisco Estevez,Dominguez, Xorge A.
Antimony Trichloride Catalysed Reactions on Cyclocostunolides
γ-Hydroxy esters (III and IV) derived from α- and β-cyclocostunolides (I) and (II), respectively undergo intramolecular transesterification on reaction with antimony trichloride in methanol.In the case of II this reaction is attended with a double bond shift.Unlike I, II undergoes an addition to the C4-exocyclic olefin.
Kalsi, P. S.,Khurana, Sarita
p. 1145 - 1146
(2007/10/02)
Antimony Trichloride Catalysed Reactions on Terpenoids
Unlike homoallylic alcohols which undergo addition to the olefin, allylic alcohols undergo substitution reaction in antimony trichloride catalysed reaction.This reaction involves a carbonium ion mechanism.However, there is a high degree of selectivity in the formation of the reaction products which have some differences in their stabilities.In case of lactones, products arising from alkyl oxygen and acyl oxygen cleavages are formed depending on the stability of the ions obtained by these cleavages.
Kalsi, P. S.,Dhillon, R. S.,Kaur, Satinder,Gupta, Rachna
p. 986 - 988
(2007/10/02)
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