Structures and Partial Syntheses of Machicendiol, Machicerionol and Machicenin-Three New Nor-Lignans from Machilus glaucescens : Preferred Conformation of the Side Chain of Machicendiol

Department of Chemistry, University College of Science, Calcutta 700 009

Three new nor-lignans, designated ( —) machicendiol, machicenonol and machicenin have been isolated from the leaves of Machilus glaucescens Wight (fam. Lauraceae). Their structures have been determined as 2-(3, 4-methylenedioxy-phenyl)-5-(1, 3-dihydro­xypropyl)-7-metboxybenzofuran ( I ), 2-(3, 4-methylenedioxy-phenyl)-5-(1-keto-3-hydroxy­propyl)-7-methozybenzofuran (II) and 2-(3,4-dimethoxyphenyI)-5-(3-palmityloxypropyl)-7- methozybenzofuran (III) respectively, largely based on their UV, PMR and mass spectral features. The structures have been confirmed by the unambiguous partial syntheses of (I) and (II) from egonol (IV) and that of (III) from homoegonol (V). Sesamin (VI), pinoresinol dimethyl ether (VII), (IV)„ (V) and β-sitosterol have also been isolated from this plant material. The preferred conformation of the 1, 3-dihydroxypropyl side chain of machicendiol has been suggested from the study of its 270 MHz PMR spectrum in CDCI₈.