M. Vanmeerssche

Chemical Studies of Marine-invertebrates .43. Novel Sesquiterpenes From Clavularia-inflata and Clavularia-koellikeri (coelenterata, Octocorallia, Stolonifera)

Abstract Two novel sesquiterpenes, 12-acetoxycyclosinularane ( 1 ) and 12-acetoxysinularene( 2 ),have been isolated from Clavularia inftata . Their structures have been determined by X-ray diffraction analysis and chemical correlation respectively. Moreover, the new aromadendrane sesquiterpene(1R * , 1aS * , 4R * , 7R * , 7aS * , 7bS * , 5Z)-4,4a,7-trihydroxyaromadendr-5-en-8-oic acid methyl ester ( 19 ) has been isolated from the related species C. koellikeri . Its structure has been established by X-ray diffraction analysis. These compounds are the first sesquiterpenes isolated from Octocorallia of the order Stolonifera.

A Novel Type of Bis-quinolizidine Alkaloid From the Sponge Petrosia-seriata

Abstract The structure of petrosin, the major alkaloid isolated from the sponge Petrosia seriata , has been determined by X-ray diffraction analysis. Petrosin is the first member of a new class of bis-quinolizidine alkaloids containing a C-16 macrocycle.

Crystal and Molecular-structure of 1-aza-5-stanna-5-chlorotricyclo[3.3.3.01,5]undecane, a 2,8,9-tricarbastannatrane

Abstract 1-Aza-5-stanna-5-chlorotricyclo[3.3.3.0]undecane crystallizes in the space group P 6 3 . The unit cell, with a 8.435(3), c 9.243(2) A, V 569.5(3) A 3 , contains two molecules. The structure was refined to a final R value of 0.057. The molecules CISn(CH 2 CH 2 CH 2 ) 3 N belong to the point group 3, and the Sn, Cl and N atoms lie on the crystallographic 3-axis. The tin atom has a trigonal bipyramidal environment with the nitrogen and chlorine atoms in apical positions. The tin-nitrogen intramolecular interaction is 2.372(29) A.

Secotrinervitane, a Novel Bicyclic Diterpene Skeleton From a Termite Soldier

Abstract The structure of 3α-acetoxy-15β-hydroxy-7,16-secotrinervita-7,11-diene, a diterpene possessing a novel bicyclic cembrane-derived carbon skeleton, has been determined by X-ray diffraction analysis.

Vicinal Alkylation of Olefins, Regioselective and Stereoselective Addition of [cm + Cn] Units To Cyclopentadiene

Adducts of alkyl(phenylthio)ketenes to cyclopentadiene are cleaved with KOH-t-BuOK with retention of configuration at three centers. This observation broadens the synthetic potential of the method of vicinal alkylation of olefins. This method has been used for the vicinal addition of [Cm + Cn] units to cyclopentadiene.

Sedum alkaloids II: sedacryptine, a new minor base from sedum acre. ☆

Abstract The structure of sedacryptine 1 , a new minor alkaloid isolated from Sedum acre , has been established by single-crystal X-ray crystallography.

Two quassinoids and two coumarinolignoids from Hannoa klaineana roots

Abstract Two new quassinoids (klaineanolides A and B) were isolated from the root bark of Hannoa klaineana and their structures elucidated by X-ray diffraction and spectroscopic methods. Two coumarinolignoids (cleomiscosins A and B) were also identified.

Icacenone, a furanoditerpene with a pimarane skeleton from Icacina mannii

Abstract Icacenone was isolated from the roots of Icacina mannii . This new diterpene has a furane ring fused to a pimarane skeleton. Its structure was established by X-ray diffraction analysis. Its spectroscopic properties are also discussed.

The Formation of 8,14-seco-steroid Systems - 3-beta,5,17-beta-trihydroxy-8,14-seco-5-alpha-androstan-8-one and its 3,17-diacetate Ester

Abstract When subjected to thermolysis under acidic conditions, the steroidal 5α,8α-peroxide 1 afforded, in addition to the 5,l0;8,9-diseco derivative 2, a monofragmentation compound, i.e. the 8,14-seco-steroid 3, the structure of which was determined by X-ray analysis of its hydrolysis product 4.

Sur une voie d'accès originale au système pyridopyrimidopyrimidinique

Resume N,N-dimethyl amino uracile when reacting with N-dimethyl phosgeniminium chloride leads to a stable amide chloride which undergoes an heterocyclization reaction with pyridine to give a pyridopyrimidopyrimidine in a good yield.