Studies in natural products,Pt.1 & 2

Abstract

Part I: Investigations on the Essential Oil of Ageratum conyzoides After briefly surveying the earlier work carried out on the essential oil of Ageratum conyzoides, the present investigation on this oil has been described. Two components-a liquid and a solid-were isolated from the essential oil of Indian origin. The liquid component was identified as 7 methoxy 2,2 dimethylchromene, a compound previously known only as a synthetic product. Using modern physical tools such as ultraviolet, infrared, and nuclear magnetic resonance spectroscopy, along with mass spectrometry, the solid component has been shown to be: 6,7,6 ,7 tetramethoxy 2,2,2 ,2 tetramethyl 3 (4 ) dehydro 3 ,4 bichroman, a compound hitherto unknown. Two alternative routes for the synthesis of this solid have been suggested.

Part II: Synthesis of the Gross Structure of Acorenone After a comprehensive review of the chemistry of sesquiterpenes having an acoranane skeleton, the present work involving the synthesis of acorenone has been described. 5 Isopropyl 5 (p methoxyphenyl) 2 pentanone, prepared by two different routes starting from anisole, was converted into 1 isopropyl 4 methylspiro[4.5]dec 6 en 8 one. From this, 1 isopropyl 4,8 dimethylspiro[4.5]decan 7 one (the gross structure of dihydroacorenone) was obtained via a four step procedure. The infrared spectrum of this compound was found to be almost identical with that of dihydroacorenone prepared earlier by Sorm through hydrogenation of naturally occurring acorenone. Finally, 1 isopropyl 4,8 dimethylspiro[4.5]dec 8 en 7 one (the gross structure of acorenone) was synthesized from 1 isopropyl 4,8 dimethylspiro[4.5]decan 7 one by a bromination–dehydrobromination sequence.