Marcel Fetizon

Ellagic compounds from Diplopanax stachyanthus

Abstract The stem bark of Diplopanax stachyanthus contains the phenolic lactones 3,3′,4′-tri-O-methylellagic acid, 3,3′,4′-tri-O-methylellagic acid 4-O-β- d -glucopyranoside and a new ellagic acid glycoside, 3,3′-di-O-methylellagic acid 4-O-β- d -xylopyranoside. The 13C NMR O-acetyl substituent effects were most useful for characterizing ellagic acid O-di- and trimethyl ethers. These effects are extended to some simple glycosyl derivatives where it is demonstrated not only that the anomeric configuration but also the exact site of the sugar substitution can be determined from such data.

Highly selective oxidations of diols by silver carbonate

The oxidation of α-, β-, and γ-di-secondary diols by silver carbonate on celite leads to hydroxy-ketones.

A new synthesis of lactones: application to (±)-mevalonolactone

Silver carbonate on celite converts primary 1,4-, 1,5-, and 1,6- diols into the corresponding lactones in high yield.

Chemistry of dihydro-1,4-dioxin III a new method for the preparation of α,α′-dihydroxy ketones from ketones and aldehydes

Title compounds, 7, were prepared from ketones and aldehydes via the intermediate 3 by methanolic peracid epoxidation followed by NaBH4 reduction and acidic hydrolysis. Application of this method to the preparation of the unnatural corticoid side chain was reported.

Synthetic studies on taxane diterpenes X-ray structure of a key intermediate

Abstract Michael condensation of the dienone (3) with the vinyllactone (19) leads to the compound (20). Attempts to construct the B ring of the taxane skeleton by direct cyclization of (20) are reported . The stereochemistry of (20) is established by X-ray structure determination.

An approach to the synthesis of optically active trichothecenes from tri-O-acetyl-D-glucal☆

Abstract A chiral synthesis of the B-C ring system of trichothecenes from tri-O-acetyl-D-glucal by using a photochemical cycloaddition of acetylene to the unsaturated ketone 7 , followed by acid-catalyzed rearrangement, is described.

1,4-dioxene in organic chemistry. Part VII regiospecific oxidative cleavage of 1,4-dioxenyl carbinols with pyridinium chlorochromate. A new method for the preparation of α-hydroxy acids and α-keto acids.☆

The allylic alcohols 1 obtained from lithiated 1,4-dioxene and ketones or aldehydes undergo regiospecifically oxidative cleavage with pyridinium chlorochromate at the dioxene double bond to give, after saponification, α-hydroxy acids. Extension of this reaction to α,β-unsaturated ketones 10 affords α-keto acids.

Synthetic Studies on Taxane Diterpenes. II1Preparation of a Key Intermediate: 7-exo-Benzoyloxy-9, 9-Dimethyl Bicyclo[3.3.1]nonan-2,4-Dione

Abstract The preparation of the title compound 1, a key intermediate in the Synthesis of taxane derivatives, from 9, 9-dimethyl bicyclo [3. 3. 1] nonan-3, 7-dione 3 is described.

Longitudinal relaxation times and structure elucidation—I : Fatty acids and esters

Abstract The 13C relaxation times of several fatty acids and esters were measured. The values obtained can be used for assigning the carbon resonances or for locating the double bond along an alkyl chain.

Une nouvelle voie d'acces aux derives du taxane

Resume The methylketal 9b, obtained in five steps from 2,6 - dimethylbenzoquinone, is transformed by photolysis into the highly functionalized taxane precursor 11d.