Marion M. Horn

5,6-dihydro-α-pyrones and two bicyclic tetrahydro-α-pyrone derivatives from Cryptocarya latifolia

Abstract Two new 6-substituted-5,6-dihydro-α-pyrones have been isolated from the bark Cryptocarya latifolia. In addition two new, closely related dioxabicyclo [3,3,1]nonan-2-one derivatives, have been obtained in lower concentration from the same plant source.

Pyrano-isoflavones with erectile-dysfunction activity from Eriosema kraussianum

Five pyrano-isoflavones have been isolated from the rootstock of Eriosema kraussianum N. E. Br (Papilionaceae). Spectral data and single crystal X-ray analyses were used for structural elucidation. The most active of the compounds had an activity of 75% of that found in Viagra in the erectile dysfunction test on rabbit penile smooth muscle.

α-pyrones and their derivatives from two Cryptocarya species

From Cryptocarya myrtifolia, cryptocaryalactone and its deacetyl derivative have been isolated for only the second time, together with the novel 7-styryl-2,6-dioxabicyclo [3,3,1]nonan-3-one. This cyclic compound could also be obtained by simple transformation of deacetylcryptocaryalactone. Cryptocarya myrtifolia also yielded the known cryptofolione and an oxidation product in trace quantities.

Stereostructure and anti-inflammatory activity of three diastereomers of ocobullenone from Ocotea bullata

A novel diastereomer of ocobullenone. designated as sibyllenone, was isolated from the stem bark of mature Ocotea bullata in the course of a search for anti-inflammatory compounds from this plant. The stereostructure was established by X-ray crystallography and corroborated by NOESY analysis. Ocobullenone, obtained previously, was re-isolated and crystallised successfully for X-ray analysis, thus making possible an accurate spatial comparison of ocobullenone, iso-ocobullenone and the new stereoisomer. Tested pharmacologically for cyclooxygenase-1 and 2, and 5-lipoxygenase inhibition, sibyllenone was the only compound from O. bullata which showed good inhibitory activity towards 5-lipoxygenase.

Transformation of naturally-occurring 1,9-trans-9,5-cis sweroside to all trans sweroside during acetylation of sweroside aglycone

From the rootstock of Scabiosa columbria L. loganin and sweroside were isolated. Sweroside showed moderate antibacterial activity. Pure sweroside was converted to the sweroside aglycone 1-acetoxy derivative (DABCO/Ac2O) after hydrolysis of the glucose unit. X-ray crystallography of the monoacetate showed unambiguously that it had been transformed to a new seco-iridoid having the novel trans diaxial configuration for the protons on C-1, C-9 and C-5. The mechanism for the rearrangement is discussed.

Reaction of 2-Formyl Imidazole with Intermediates From the Baylis-Hillman Reaction

Abstract The reaction of formyl imidazole (in the presence and absence of DABCO, and with either THF or methanol as solvent) with α-hydroxylaryl derivatives of methyl acrylate affords novel synthetic intermediates. By controlling the reaction conditions, either allylic substitution products (THF, DABCO) or rearrangement (MeOH, no DABCO) products result.

Iso-ocobullenone and a neolignan ketone from ocotea bullata bark

Abstract A new neolignan, which differs from ocobullenone at a single chiral centre, and a neolignan ketone, possibly a precursor of the ocobullenones, have been isolated from the stem bark of Ocotea bullata .

Absolute configuration of α-pyrones from Cryptocarya latifolia and Syncolostemon densiflorus

The stereochemical structures of two α-pyrones previously isolated from Cryptocarya latifolia have been shown to be 6R-[2R,4S,6S-(triacetoxy)-heptyl]-5,6-dihydro-2H-pyran-2-one and 6R-[2S,4S-(diacetoxy)-pentyl]-5,6-dihydro-2H-pyran-2-one. Syndenolide from Syncolostemon densiflorus is 6R-[5S-(acetoxy)-1R,2R,3S-(trihydroxy)-heptyl]-5,6-dihydro-2H-pyran-2-one.

Absolute configurations of all four stereoisomers of cryptocaryalactone and deacetyl cryptocaryalactone

Using information available in the literature and correlating this with physical data obtained for cryptocaryalactone stereoisomers isolated from C. myrtifolia and C. wyliei, it has been possible to assign the absolute configurations of the four stereoisomers of the title compound and its deacetyl analogue.

Stereostructure, conformation and reactivity of P- and a-gardiol from Burchellia bubalina

Abstract From the leaves of Burchellia bubalina (Rubiaceae) pure P- and a-gardiol have been isolated, the latter in crystalline form for the first time. X-ray analysis of P-gardiol establishes its relative configuration. Treatment of the tosyl derivative of P-gardiol with base affords a crystalline elimination product amenable to X-ray analysis. Evidence is presented for the partial conversion of a-gardiol to the epimeric P-gardiol at room temperature. Molecular dynamic studies at 1000 K on the two gardiols provide useful conformational information. In the case of P-gardiol, the analysis shows interesting correlations between conformations adopted at 1000 K and those present in the crystalline state at room temperature.