Marie-Paule Heitz

Direct conversion of tetrahydropyranylated alcohols to the corresponding bromides

Various tetrahydro-2 pyranyl protected alcohols are converted into the corresponding bromides by PPh3 / CBr4, with inversion of configuration, and in high yield.

Stabilisation de molecules hyperactives par complexation: Le formyl-2 butadiene fer-tricarbonyle. Preparation, dedoublement et reactivite☆

Abstract The stable dieneiron tricarbonyl complex of the unstable 2-formylbutadiene was prepared from isoprene by two different ways and resolved via chiral semioxamazone formation. The complex reacts easily with Grignard or other carbanionic reagents leading to the corresponding alcohols from which the stable diene alcohols can now be obtained by decomplexation. The reaction of the aldehyde complex proceeds nearly diastereospecifically with organolithium compounds and cuprates, these reagents showing an inversed diastereoselection. This contrasts with the behaviour of magnesium and titanium derivatives which lead only to mixtures of those diastereoisomers. Wittig and Horner-Emmons olefinations were also studied in order to examine the diastereoselectivity of the subsequent diazoalkane cycloaddition and the possibility for synthesis of Ips-type insect pheromones via hydroboration.

Synthese stereo et enantioselective par l'intermediare de complexes du fer de derives chrysanthemiques dieniques et d'aldehydes hemicaroniques cis et trans.

Abstract A stereo and enantioselective synthesis of cis and trans hemicaronic aldehydes, starting from the optically active sorbic aldehyde-irontricarbonyl comples, is described.

Une methode simple de liberation des ligands organiques de leurs complexes de fer carbonyle.

Resume Disengagement of organic ligands from their Ironcarbonyl Complexes is easely achieved by oxidation with aqueous hydrogen peroxide under basic conditions.

Convenient preparation of bromoalkynes from primary alkynes and PPh3 / CBr4

Abstract 1-Bromo-1-alkynes are prepared in high yields under very mild conditions by treatment of primary alkynes with PPh3/CBr4.

Un equivalent synthetique chiral du prenal, le formyl-trimethylenemethane (fer) tricarbonyle. synthese du (r)-(-)-ipsdienol

Abstract Formyl-TMM (Iron)tricarbonyl 3 reacts with a high diastereoselectivity with organozinc derivatives to Iron stabilized TMM-alcohols. These are decomplexed, under partial hydrogenation, by photolysis in acetic acid to give allylic and homoallylic isoprenoic alcohols. Starting from the optically active complex (+)- 3 , this allows a rapid synthesis of (R)-(-)-Ipsdienol of high ee.

Syntheses of tetrahydropyrans by PPh3/CBr4 induced cyclization of acetals: Application to a synthesis of rose oxide

Abstract Substituted tetrahydropyrans are prepared in good yields by PPh3/CBr4 induced cyclization of acetals. The utility of this new procedure is illustrated by the synthesis of cis-2-(2-methyl-1 propenyl)- 4 methyltetrahydropyran (rose oxide).

Carbanions en α de sites coordonnés au fer-tricarbonyle. I: Carbanion dérivant du (butadiényl-2 fer-tricarbonyle)-2 dithiane-1,3

Abstract In contrast to complexed cations, little is known about carbanions which are adjacent to tricarbonyliron coordinated sites, especially in the case of acyclic ligands they seem difficult to synthesize. The present work devoted to such dithiane-stabilized carbanions has shown that this is true for the trimethylenemethane- and 1-butadienedithiane complexes. However, a reactive ambidentate carbanionic species was obtained by deprotonation of the dienetricarbonyliron complex of 2-(2-butadienyl)-1,3-dithiane. Another surprising result with the 2-(2-butadienyl)-1,3-dithiane complex anion was the observation of a sharp dichotomy in its reactions with alkyl halides on the one hand and aldehydes or water on the other. With the former electrophiles, 2-substituted 1,3-dithianediene complexes are obtained. The latter lead to sulphur disubstituted trimethylenemethane complexes, the electrophile being bonded to the carbon atom 4 of the starting diene unit. The corresponding uncomplexed carbanion shows analogous reactivity but with the carbonyl electrophiles bonded to the former 1 of the diene.

Methode electrochimique de liberation d'un ligand organique de son complexe de fer carbonyle

Summary Disengagement of organic ligands from their iron carbonyl complexes is performed by direct electrochemical oxidation or by mediated electron transfer with aromatic tertiary amines.

Complexation de la dehydro-β ionone par le fer carbonyle ; un complexe inhabituel de fer dicarbonyle.

Resume By complexation with Iron carbonyls, dehydro-B ionone yields three differents complexes, depending on the reaction conditions. The most stable of them is the unusual bis π-allylirondicarbonyl complex IV whose structure was determined by X ray diffraction