The structure of neoisostegane, l_, a new bisbenzocyclooctadiene lignan lactone was elucidated from its 'H and 13C NMR spectra and by chemical correlation with known steganes. In the course of isolating known steganes from Steganotaenia araliacea Hochst. (Apiaceae)]" for use in another study, neoisostegane, I, a new bisbenzocyclooctadiene lignan lactone, was is01ated.~ Unlike the homologous lignans previously isolated by Kupchan and coworkers,' neoisostegane, 1, bears no functionality at C-5. Thus, it is the first naturally occurring stegane to be reported.4 An ethanolic extract of 5. araliacea was prepared and fractionated according to previously established protocols.* Preparative thin-layer chromatography of a fraction derived from the chloroform partition layer yielded 1. as a crystalline solid, mp 107 -108" (EtOH). High resolution mass spectrometry established the molecular formula of 1. as C23H2607 (m/e 414.1702, calc'd. --414.1679), and the IR spectrum displayed a band at 1776 cm-', indicating the presence of a lac- tone. The 90 MHz 'HNMR spectrum (CDC13)5 showed 3 one-proton singlets at 66.72, 6.69, and 6.52, 3 three-proton singlets at 63.96, 3.89, and 3.86, and 1 six-proton singlet at 63.94. These data suggested that 1 was a bisbenzocyclooctadiene lignan lactone bearing five methoxyl groups rather than the more usual three methoxyl groups and one methylenedioxy moiety. CH30 CH30 CH30 0CH3 1 _ CH30 OCH3
2SG7