Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Patent
1994-04-25
1995-06-20
Dees, Jose G.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
568312, 568343, C07F 1300, C07C 4500
Patent
active
054262011
DESCRIPTION:
BRIEF SUMMARY
This application is a request for U.S. examination filed under 35 USC 371 of International application No. PCT/FR92/000877 filed on Sep. 21, 1992.
The invention relates to a novel method of preparing manganous enolates and to its applications.
The utility of enolates in general is well recognized, particularly since the work by FLEMING et al. ("Synthesis" 1976, 736, and "Chem. Soc. Rev." 1981, 10, 83); these compounds are used especially as intermediates in different chemical reactions. They make it possible, for example, to obtain various esters, ketones or aldehydes which are useful in perfumery or as starting materials for the production of drugs or pesticides. Particularly valuable enolates, namely manganous enolates, form the subject of a French patent application published under no. 2 639 939. According to said document, manganous enolates are prepared by reacting mixed organomanganous compounds with ketones.
The advantages of Mn enolates include, for example, that of avoiding the polyalkylation or polyalkarylation of the ketone when these enolates are reacted with alkyl or alkaryl halides; by contrast, alkali metal and alkaline earth metal enolates, in particular lithium enolates, lead to a greater or lesser degree of polyalkylation or polyalkarylation. On the other hand, certain organomanganous compounds, particularly amides prepared by the method referred to above, give relatively inadequate yields in some of their applications, such as esterification or silylation reactions.
The present invention provides an improvement which, while retaining the advantage of avoiding polyalkylation or polyalkarylation, makes it possible substantially to increase the yield of reactions where organomanganous compounds were somewhat deficient.
The method according to the invention for the preparation of manganous enolates comprises treating an alkali metal or alkaline earth metal enolate with a manganous compound in a solvent for the Mn enolate to be prepared.
As alkali metal and alkaline earth metal enolates and their preparation are known, it is not necessary to describe them in detail here, suffice it to say that they are usually compounds of Na, K, Li, Ca or Mg, especially Li. Their preparation consists in reacting a corresponding organometallic compound with an organic compound carrying at least one carbonyl, particularly a ketone. The reaction is carried out in a solvent, generally at between -78.degree. C. and +100.degree. C., room temperature being suitable in many cases.
The reaction according to the invention, which constitutes a transmetalation, can be represented as follows: ##STR1## M' being a monovalent metal, M" being a divalent metal and it being possible for X and Y, which are identical or different, to be non-oxidizing anions or amino groups. MnX.sub.2 can be replaced with YMnX. Manganous halides, especially MnCl.sub.2, are suitable as MnX.sub.2.
Lithium enolates, where M' is Li, are particularly suitable.
In general, depending on the nature of the compounds involved, the temperature of the reaction medium is adjusted so as not to affect the stability of the reactants and so as to obtain the desired product in a reasonable period of time, for example in 0.3 to 3 hours. The preferred temperatures range between about -78.degree. and +100.degree. C. and in particular from 10.degree. C. to 50.degree. C.; one of the advantages of the method is that room temperature is suitable in many cases, it being possible for the reaction to be completed in about 0.5 to 2 hours at temperatures of 15.degree. to 30.degree. C.
The molar ratios of the reactants according to reaction (1) or (2) indicated above are usually stoichiometric, but it can be useful to employ an excess of manganous salt MnX.sub.2 of, for example, 0 to 100% relative to stoichiometry, i.e. 1 to 2 mol per mol of enolate, but a deficiency thereof for reaction (3).
The method of the invention can be carried out with various concentrations of the reactants in the solvent used; the preferred concentrations range between about 0.1 and 2 mol or, prefera
Cahiez Gerard
Clery Patrick
Laffitte Jean-Alex
Dees Jos,e G.
Nazario-Gonzalez Porfirio
Societe Nationale Elf Aquitaine
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