Alloaromandendranes, bicyclogermacrane and 2,3-secoalloaromandendranes in cultured cells of the liverwort, Heteroscyphus planus

Novel ent-alloaromandendranes, planotriol and its acetates, and four ent-2,3-secoalloaromandendranes including two novel compounds in nature and one novel ent-bicyclogermacrene were isolated from cultured cells of the liverwort, Heteroscyphus planus. The absolute configuration of planotriol and its acetates were determined by a single X-ray analysis and H-1 NMR spectroscopy after derivatization with an axially chiral agent, 2-(2'-methoxy-1'-naphthyl)-3,5-dichlorobenzoic acid (MNCB). Planotriol diacetate was chemically converted into the known ent-2,3-secoalloaromandendrane, (-)-hanegokedial, suggesting that the 2,3-dihydroxy-alloaromandranes might be immediate precursors for 2,3-secoalloaromandendranes, The absolute stereochemistry of the bicyclogermacrane and the 2,3-secoalloaromandendranes was also determined by H-1 NMR analysis of the MNCB esters and chemical correlation. Copyright (C) 1996 Elsevier Science Ltd