Pietro Venturella

New diterpenes from Sideritis sicula

Abstract Two new diterpenes have been isolated from Sideritis sicula : sideripol, ent -18-acetoxy-7α-hydroxykaur-15-ene and epoxysideritriol, ent -15β,16β-epoxykauran-7α,17,18-triol. The previously known diterpene eubol, ent -7α-acetoxykaur-16-en-15β,18 diol has also been obtained from the same source.

Eubotriol and eubol, new diterpenes fromSideritis euboea

2 new diterpenes Eubotriol (ent-kaur-16-ene-7α, 15β, 18triol) (I), and eubol (ent-kaur-16-ene-7α-acetoxy-15β, 18 diol) (II) have been isolated from Sideritis euboea Helder.

Coumarins from Seseli bocconi

Abstract A new khellactone, bocconin, in addition to known compounds, have been isolated from Seseli bocconi subsp. bocconi and subsp. praecox Gamisans . Their structures were elucidated on the basis of spectral analyses and hydrolytic studies.

Siderone, a diterpene from Sideritis syriaca

Abstract Siderone, a new keto-diterpene, has been isolated from the petrol extract of the inflorescence of Sideritis syriaca . Its structure and stereochemis

Ucriol, an epoxy-diterpene from Sideritis syriaca

Abstract The isolation of a new epoxy-diterpene from the inflorescence of Sideritis syriaca (S. sicula Ucria) is described. Its structure and stereochemistry were established by spectroscopy and partial synthesis.

Phytochemical Investigation of the Labiate Dorystoechas hastata

Abstract Carnosol (11,12-dihydroxyabieta-8,11,13-trien-20-oic acid 20,7-lactone), and rosmanol (7α, 11, 12-trihydroxy-abieta-8, 11, 13-trien-20 oic acid-20, 6-lactone), two abietane diterpenes previously isolated from Rosmarinus officinalis, have been isolated from leaves of Dorystoechas hastata. Luteolin, luteolin-7-glucoside, 6-methoxyluteolin-7-glucoside, caffeic acid and chlorogenic acid have also obtained from the same source. The co-occurrence of carnosol, rosmanol and 6-methoxyluteolin-7-glucoside support the close relationship of these two genera.

A diterpene, distanol, from Sideritis distans

Abstract A new diterpene, distanol, has been isolated from the petrol extract of the aerial part of Sideritis distans Wild. Its structure stereochemistry has been assigned by spectroscopic methods.

Carbon-13 Nuclear Magnetic Resonance Spectra of 2-Arylidene-3(2H)-benzofuranones

Etude de la structure des arylidene-2(2H) benzofuranones-3 substitues a partir des spectres RMN de 13 C, et discussion sur les effets substituants

Partial synthesis of ent-kaur-16-ene-15β,18-diol and ent-kaur-16-ene-7α,15β,18-triol

Treatment of ent-15β,16β-epoxykauran-18-ol (V) with boron trifluoride–ether complex in dimethyl sulphoxide or direct photo-oxygenation of ent-kaur-15-en-18-ol (IV) gave the expected ent-kaur-16-ene-15β,18-diol (I). This product is suggested to be identical with natural candidiol. Treatment of ent-15β,16β-epoxykaurane-7α,18-diol (VIII)(natural sideroxol) with boron trifluoride–ether complex in dimethyl sulphoxide or photo-oxygenation of ent-kaur-15-ene-7α,18-diol (II)(natural sideridiol) gave ent-kaur-16-ene-7α,15β,18-triol (VII).

Further reactions of sideridiol [(–)-kaur-15-ene-7β,19-diol]

The secondary hydroxy-group of sideridiol [(–)-kaur-15-ene-7β,19-diol](I) has been confirmed as being in the 7- rather than the 12-position. Bromination of methyl (–)-7-oxokauran-19-oate (IXb) gives methyl (–)-6β-bromo-7-oxokauran-19-oate (Xb); treatment of the latter with base gives (–)-7-oxokaur-5-en-19,6-olide (XII) mainly. Better yields of lactone (XII) are obtained by heating a solution of bromo-ester (Xb) in dimethyl sulphoxide under reflux. The n.m.r., o.r.d., and c.d. data for the bromo-ester (Xb) are discussed.