New diterpenoids from Pterodon emarginatus vog.

Abstract

Eight new diterpenoids isolated from Pterodon emarginatus Vog. have been assigned the following structures and stereochemistry: 6α,7β-diacetoxyvouacapane (1),7β-acetoxyvouacapane(3),6α,7β-dihydroxyvouacapan-17β-oic acid (11), methyl 6α,7β-dihydroxyvouacapan-17β-oate (12), methyl 7β-acetoxy-6α-hydroxyvouacapan-17β-oate (14), 6α-acetoxyvouacapano-17β,7β-lactone (16), vouacapane-6α,7β,14β-triol (25), and 6α,7β-diacetoxy-vouacap-14(17)-ene (24). Compound (24) was hydrogenated (Pd–C) to 6α,7β-diacetoxy-14-epi-vouacapane (20). The same 14-epi-diacetate (20) was obtained by reduction with lithium aluminium hydride of the 17-tosylate (18) derived from vouacapane-6α-7β17-triol (17). 7β-Acetoxyvouacapane (3) has been converted into the parent furohydrocarbon [vouacapane (6)] by Wolff–Kishner reduction of the derived vouacapan-7-one (5). N.m.r. and mass spectra of several compounds are described.