J.-C. Jacquesy

Ester- and ether bond cleavage in immature kerogens

Abstract Quaternary ammonium salt Aliquat 336 and 18-Crown-6 enhance hydrolysis of Timahdit-M kerogen when used as a phase transfer catalyst. The yield of hydrolysis products was higher with Aliquat than with 18-Crown-6, but the identified products were found in lower concentration, the difference being soluble heavy parts from kerogen which cannot be analyzed directly. Both reactions afforded series of aliphatic mono- and dicarboxylic acids, alkylsuccinic acids and alkanols, but differences in distributions were observed. The range of monocarboxylic acids was shorter with Aliquat than with 18-C-6, C14C18 compared to C12C32, but palmitic and stearic acids were dominant in the two cases. C10 and C12 alkyl succinic acids were identified in Aliquat products. Aromatic acids were the major hydrolysis products (59%) with crown ether; only one aromatic acid was found with Aliquat. Hydrocarbons and tertiary amines were obtained from both reactions, they were obviously present in the kerogen as trapped molecules. Many tertiary amines arising from the decomposition of the reagent were obtained with Aliquat. The results give evidence of an important reticulation involving ester groups in the Timahdit-M kerogen. Series of n-, iso- and anteisoalkanes were obtained through HI/LAD treatment of Irati and Aleksinac kerogens, originating probably from glycerol-ether lipids. C27C34 α,β-hopanes were also found to be linked to kerogen (Irati) by ether bonds. Reaction with CF3CO2H (Irati) afforded seven series of branched alkenes, indicating that branched saturated alkyl chains were bound to aromatic moieties of kerogen by ether groups. Acetates of cholesterol and 24-ethylcholesterol were identified in the BF3-Et2O/Ac2O products. Esters of fatty acids (max C16, C18) were also identified. Only alkanes were produced on AII3 reaction. Each reaction afforded the same series of n-alkanes. This would reflect modifications in the kerogen matrix during these various treatments, resulting in the release of tightly trapped molecules.

Polar lipid fraction in soil: a kerogen-like matter

Lipid extracts from two acidic hydromorphic soils contained simple lipids and a slightly soluble fraction (named polar fraction or complex lipids). Ether- and ester-bond cleavage and KMnO4 oxidation of the polar fraction was followed by GC-MS analyses of the released compounds. In contrast to n-alkanols and α,ω-diacids, normal monoacids were found to be the same as in simple lipids. It is concluded that the polar fraction of the soil corresponds to highly aliphatic macromolecules with a polyethylene-like structure, in which some simple lipids may be incorporated to form a protokerogen.

Enantiodivergent synthesis of (+) and (−) altholactone from D-glucose. Preparation and cytotoxic activity of analogs

Total synthesis of (+)altholactone (goniothalenol), an antitumor pyrone isolated from an unnamed polyalthea species and from goniothalamus giganteus, has been completed in 11 steps from D-glucose using the easily available aldehyde 7. Starting from the same compound or from the related benzoate 24 an enantiodivergent synthesis of (−)1 has also been completed using as the key step an efficient arylation in anhydrous HF. Under these conditions, epimerization at C-8 occurs partially to give the new 8-epi (+)1 or its enantiomer. Most of these pyrones show interesting cytotoxicity in vitro against L1210 leukemia.

A new chiral route toward terpenoids. Annulation of carvone to trans- and cis-fused bicyclic synthons

Abstract Starting from carvone, 1 two consecutive alkylations at C-6 followed by an acid-catalyzed cyclization give new bicyclic ketones which are potentially useful chirons for synthesis of terpenes such as drimanes, labdanes and triterpenes. The stereoselectivity of the second alkylation step which determines the stereochemistry of the ring junction has been studied and the results explained by the model of Tomioka. Several types of products may be formed depending on the acid used and a rearrangement has been observed in one case.

Total synthesis of (+) altholactone (goniothalenol) from D-glucose

Abstract The first total synthesis of the antitumor (+) altholactone is described from D-Glucose.

A general route to 11-deoxyanthracyclines

Abstract Diels-Alder type cycloaddition of unsaturated ketene acetal 5 with various naphtoquinones affords a short and regiospecific access to tetracyclic ketones, key intermediates for the further synthesis of 11-deoxyanthracyclines.

Nucleophilic para-fluorination of 4-alkylphenols by hypervalent iodine reagent and pyridinium polyhydrogen fluoride (PPHF) : a novel route to 4-fluorocyclohexa-2,5-dienones

Abstract Ipso-fluorination of 4-alkylphenols with C 6 H 5 -I(OCOCF 3 ) 2 -pyridinium polyhydrogen fluoride (PPHF) yields 4—fluorocyclohexa-2,5-dienones.

Solubilization of Timahdit (Morocco) oil shale kerogen catalysed by 18-crown-6

Abstract 85% of Timahdit oil shale kerogen (intermediate type I-type II) can be solubilize using potassium hydroxide 18-Crown-6 complex. The kerogen is almost unreactive (

Synthesis of hydroindolenones and hydroquinolenones by hypervalent iodine oxidation of mono or bicyclic phenols

Abstract Methoxy or fluoro hydroindolenones and hydroquinolenones can be obtained by oxidation of the corresponding 4-substituted open-chain phenolds with C 6 H 5 I(OCOCF 3 ) 2 with methanol or pyridinium polyhydrogen fluoride followed by an intramolecular conjugate addition. The corresponding cyclo 2,5-hexadienones can be obtained directly by a similar oxidation of the bicyclic phenols.

Nitronate anions as precursors of hydroxynitrilium ion equivalents in electrophilic aromatic substitution - a novel route to oximes

Abstract Nitronate salts RCHNO 2 Na react with aromatics ArH in acidic conditions to yield the corresponding oximes ArCRNOH via protonated nitronic acids.