Monique Rambaud

Monohalomethyllithium XCH2Li: stabilization of a potential synthetic reagent

Abstract The preparation of monohalomethyllithium XCH 2 Li is achieved by Bromine-lithium exchange from the corresponding Bromohalomethane in the presence of one equivalent of lithium bromide at −110° in THF-Ether-Pentane solutions. This reagent, on coupling with various carbonyl compounds leads to halohydrins, epoxides and α-halomethyl ketones with high yields.

A short large scale synthesis of (±) sarkomycin esters

Abstract : (k) Sarkomycin ethyl ester has been prepared in four steps from ethyl actylate. We have previously described the substitution of a-functionnal acrylic esters by Grignard reagents in the presence of a catalytic amount of copper (I) (1). This reaction can be applied to lithium enolates (ester or ketone). It gives then rise to new a-substituted functional actylates which are of great interest for the synthesis of biological active compounds (a-methylene &valerolactone, (+)-sarkomycin). CH,OAc flc”” =(COOEt FOOEt v 2.5% Cu(l), -7O”C, THF-Et20 - CH20Ac + COOEt Li-CH,-COOt-Bu THF-Et20, -80°C -CH2 Yield 83% COOEt ===c CH,-CH,-COO,-BU 1 Yield 66% A recent publication (2) on the synthesis of (+) sarkomycin including the same phosphonate 3 as a key intermediate prompts us to describe here our results. Many other preparations of (k) sarkomycm (or its esters) have been reported by mutli step syntheses (2, 3) with low overall yields. We report here a very short, large scale and improved synthesls of two (&) sarkomycin esters using low cost products and methodology. a-Methylene glutaric acid diester 1 can be included in a very short

Substitution nucleophile d'acetates de cyclenols allyliques fonctionnels par des organometalliques en presence de sels cuivreux. Application a une synthese rapide de la (±)Mitsugashiw alactone

Abstract Substitution of functional allylic cycloalkenol acetates by Grignard reagents (primary , secondary, tertiary-alkyl, vinyl, aryl) in the presence of a catalytic amount (2.5% equivalent) of cuprous iodide at low temperature, gives high yields of various functional α-substituted cycloalkenes . The reaction can be applied to lithium enolates of esters and need no catalyst, but may be performed with HMPA as cosolvent. It is illustrated by a short (6 steps) and efficient total selective synthesis of (±)-mitsugashiwalactone from 2,5-dimethoxy tetrahydrofuranne with 33% overall yield.

La reaction de wittig-horner en milieu heterogene VI1. Selectivite de la reaction sur des composes bifonctionnels

Abstract Heterogenous media of low basicity (K2CO3 or KHCO 3), liquid-liquid or solid-liquid allow the Wittig-Horner reaction of fragile and unprotected aldehydes (hydroxyaldehydes, nitroaldehyde and ketoaldehydes) with excellent yields. The reaction is applied to the synthesis of Royal Jelly acid and Queen Substance of Honey bee.

La reaction de Wittig-Horner en milieu heterogene IX. Bis aldolisation des phosphonates a partir des dialdehydes aliphatiques en milieu aqueux peu basique. Synthese de cyclenols fonctionnels.☆

Abstract Aqueous solutions of glutaraldehyde and succinaldehyde give respectively improved yields of 1-functional 6-cyclohexenols and 5-cyclopentenols, when subjected to WITTIG-HORNER reaction in water at room temperature, with potassium carbonate as a base.

Esters α-méthyléniques par substitution d'éthers et d'acétates dérivés de l'α-(hydroxyméthyl)acrylate d'éthyle

Abstract α-(Methylene)alkanoic esters are prepared in high yields by substitution of α-(acetoxymethyl)acrylates using Grignard reagents in the presence of a catalytic amount of copper(I) salt. This reaction can be applied to lithium enolates of esters and ketones and to give functional α-(methylene) alkanoic esters, products of great interest for the synthesis of active biological compounds (sarkomycin, α-(methylene) δ-valerolactone).

Wittig-Horner Reaction in Heterogenous Media VII. A New Strategy for the Total Syntheses of the Royal Jelly Acid and the Queen Substance of Honey-Bee

Abstract A new general scheme for the preparation of Royal Jelly acid and Queen Substance of Honey-bee, including, as the key steps, copper I catalyzed addition of functional (protected alcohol and ketone) Grignard reagents to acrolein diethylacetal, and the Wittig-Horner reaction of unprotected 8-hydroxyoctanal and 7-oxo-octanal with triethylphosphonoacetate in water, in the presence of potassium carbonate.

The Wittig-Horner Reaction in Heterogenous Media VIII1. Cyclisation During the Aldolisation Step from Aqueous Glutaraldehyde

Abstract The Wittig-Horner reaction can be performed in an aqueous medium using a 6 - 9M potassium carbonate solution as the basel1,2. This new technique provides good yields of various a-functional olefines from aldehydes. It allows the use of functional aldehydes without protection or aqueous stabilized solutions of unstable pure aldehydes without previous isolation (formaldehyde, crotonalde3 hyde2).

Esters α-méthyléniques et α-hydroxyméthylés par addition d'organolithiens ou magnésiens sur l'α-(hydroxyméthyl) acrylate d'éthyle et ses dérivés en présence de cuivre(I)

Resume α-(Methylene)- and α-(hydroxymethyl)-alkanoic esters are prepared by substitution of α-(acetoxymethyl) acrylate by Grignard reagents in the presence of a catalytic amount of copper(I) salt, or by addition of an excess (2.5 equivalents) of dialkylcopper magnesium halides to ethyl-α-(hydroxymethyl) acrylate in THF.

Une methode tres simple et reproductible de dosage des solutions etherees de LiAlH4

A new, simple method is described for the accurate titration (reproducibility ± 2%) of a solution of LiAlH4 in diethyl ether. It is based on the reaction of benzyl alcohol with the deep-violet complex formed between LiAlH4 and 1,10-phenanthroline in THF in the presence of magnesium salts.