Francis Rouessac

Synthesis of Substituted Dicyanomethylendihydrofurans

Abstract A simple and efficient method for the preparation of the title compounds is described from α-ketols and malononitrile in the presence of sodium ethylate at room temperature. These compounds lead to unsaturated derivatives by condensation with aldehydes.

Un dienophile chiral tres reactif : le Z-(R)S p-tolylsulfinyl-3 propenoate de methyle

Abstract Methyl Z-(R)S 3-p-tolylsulfinyl propenoate reacts under mild conditions with cyclopentadiene. A high stereoselectivity and diastereospecificity were observed. The structure and absolute stereochemistry were established by N.M.R.

L'araliangine, nouveau lignane bisbenzocyclooctadienolactonique de Steganotaenia araliacea, Hochst.

Abstract Isolation of a new lignan from antileukemic fraction of Steganotaenia araliacea Hochst. and structure elucidation using 400 MHz PMR to observe benzylic coupling.

Acces aux (R)S acyl-1 vinyl p-tolylsulfoxydes a partir du (R)S dimethylamino-2 p-tolylsulfinyl-1 ethane. Leurs reactivites en tant que dienophile.

An efficient sequence is described whose key step involves an Hofmann elimination of (R)S 2-dimethylamino-1 p-tolylsulfinyl ethane to obtain chiral (R)S 1-acyl-vinyl p-tolylsulfoxides. Reactivity and stereoselectivity are discussed in the Diels-Alder reaction.

Neoisostegane, a new bisbenzocyclooctadienolactonic lignan fromSteganotaenia araliacea, hochst.Tetrahedron Lett., 24, 197, (1983).

The structure of neoisostegane, the first naturally-occurring stegane analogue to be described, was determined by analysis of spectral data, particularly by the application of1H -1H long range selective proton decoupling experiments at 400 Mhz.

Isolement du prestegane B à partir de Steganotaenia araliacea Hochst., premier lignane bis-(meta-hydroxy-benzyl)-butanolide d'origine végétale.―Isolement et synthèse en une étape du diméthylmatairésinol―

Abstract Prestegane B -the first higher plant occured dibenzyl butanolide lignan with two meta -phenols- and its dimethylether were isolated from S.araliacea and the structure determinations were performed with the aid of high resolution NMR and Mass fragmentation for the former, and with 2-D J resolved 1 H NMR studies and synthesis for the latter.

Cyclisation de composes ethyleniques par assistance d'ions seleniraniums

Resume Acid-catalyzed cyclization of ethylenic selenolactone 3 derived from homogeranic acid 1 affords one bicyclic lactone 5 . This intramolecular rearrangement is induced by a seleniranium ion.

A new synthetic route to optically active α-alkyl- 2- and 3-furylcarbinols by intramolecular diastereoselectivity

Abstract We report the results of intramolecular asymmetric alkylation of enantiomerically pure 2- and 3-furaldehydes containing a p-tolylsulfoxide group, thus providing an efficient method of obtaining optically active α-alkyl-2- and 3-furanmethanol of known configuration after cleavage of the sulfoxide group. In example, R and S α-phenyl-3-furanmethanol are described.

Synthesis of earthy-mouldy smelling compounds-I stereoselective synthesis of (±)-geosmin

Abstract The strongly earthy-smelling compound (±)-geosmin 1 is obtained stereospecifically in four steps and 42% overall yield from 1,4aβ-Dimethyl-4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one 2 . The key step involves a one-pot double-reduction of an epoxytosylate.

Synthèses de la (+)-marmine, des (+)-epoxy-6',7'- et (−)-epoxy-3',6'-auraptenes et des racémiques correspondants

Abstract The title compounds were prepared by short enantioselective syntheses from 7-geranytoxycoumarin. The key step to induce optical activity was a SHARPLESS epoxidation. Conditions of electrophilic cyclization were found to obtain good yields. This approach allowed also to obtain the glycol (+)-marmin.