Karl H. Pegel

Cucurbitane triterpenoids from the leaves of Momordica foetida

The chloroform extract of the leaves of Momordica foetida has yielded 3β, 7β, 23ξ-trihydroxycucurbita-5,24-dien-19-al, 3β, 7β; 25-trihydroxycucurbita-5,23-dien-19-al and 3β,7β-dihydroxy-25-methoxycucurbita-5,23-dien-19-al and the novel compounds 5β,19-epoxy-25-methoxycucurbita-6,23-diene-3β,19-diol, 5β,19-epoxycucurbita-6,23-diene-3β,19,25-triol, 5β,19-epoxy-19-methoxycucurbita-6,23-diene-3β,25-diol, 5β,19-epoxy-19,25-dimethoxycucurbita-6,23-dien-3β-ol and 5β,19-epoxy-25-methoxy-cucurbita-6,23-dien-3β-ol.

Constituents of Bridelia micrantha

Abstract The compounds friedelin, taraxerone, epifriedelinol, taraxerol, gallic acid and ellagic acid have been isolated from Bridelia micrantha. The presence of leucodelphinidin and caffeic acid was also indicated.

Diterpenes from the timber of 20 Erythroxylum species

Abstract Timber extracts of 20 species of Erythroxylum have been examined, yielding 31 known compounds and 12 new compounds which have been identified. Erythroxylum brevipes , E. cuneifolium , E. minutifolium , E. neocalidonicum , E. myrsinites and E . sp. nov. Guaricipo. did not appear to contain diterpenes, but only long-chain aliphatic material, which was not investigated. A preliminary investigation was made of E. ecarinatum (similar to E. pictum ), E. ellipticum , (similar to E. australe ), and E. rufum (unidentified diterpenes) but was not extended, due to shortage of material.

Constituents of Syzygium cordatum

Abstract Friedelin, epi-friedelinol, β-sitosterol, arjunolic acid, gallic acid, ellagic acid (hexahydroxydiphenic acid), glucose and a gallic acid-ellagic acid complex were isolated from wood and bark of Syzygium cordatum. Leucodelphinidin and leucocyanidin were detected in bark and leaf.

The characterisation of mollic acid 3β-D-xyloside and its genuine aglycone mollic acid, two novel 1α-hydroxycycloartenoids from combretum molle

The characterisation of a further novel 1α-hydroxycycloartane glycoside, mollic acid 3-β-D-xyloside, and of its genuine aglycone mollic acid is reported. Three new hydrolysis artifacts of the aglycone have been prepared and 13C .n.m.r. spectral data for these compounds are tabulated.

Diterpenes from the timber of Erythroxylum pictum

Abstract Extracts of timber of Erythroxylum pictum yielded sitosterol and 29 diterpenes, of which 15 are new. These include a small group of 4,5- seco -ro

Jessic acid and related acid triterpenoids from Combretum elaeagnoides

Abstract A novel triterpenoid acid, jessic acid, was extracted from the leaves of Combretum elaeagnoides, where it was found together with its methyl ester and its α- L -arabinopyranoside, all three compounds occurring in significantly large amounts. Jessic acid is 1α,3β-dihydroxy-23-oxo-24-methylenecycloartan-30-oic acid.

Diterpenes from the timber of Erythroxylum australe

Abstract Extracts of timber of Erythroxylum australe yielded 21 identified diterpenes, of which 10 are new.

Terpenoid ring a α-ketol sulphonate ester solvolysis: conversion of ent-3β-hydroxybeyer-15-en-2,12-dione to the isomeric ent-1α-hydroxybeyer-15-en-2,12-dione

Abstract Acetolysis of tetracyclic diterpenoid 3-equatorial, 3-axial or 1-axial sulphonate-2-ketones results in attack at the 1-axial position. Jones oxidation of the derived 1-hydroxy-2-ketone results in an unexpected ring contraction-decarboxylation giving a 2-nor-1-ketone.