Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1996-05-15
1998-11-03
Robinson, Allen J.
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568880, 568881, C07C 2914
Patent
active
058311335
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/IB95/00836 filed Oct. 6, 1995.
TECHNICAL FIELD AND PRIOR ART
The reduction of carbonyl compounds such as aldehydes, ketones, esters or lactones is a choice reaction for the general preparation of alcohols. In this context, the reduction of the carbonyl function in the compounds having other unsaturated groups in the molecule, such as ethylenic or acetylenic carbon-carbon functions, presents some difficulties due to the generally poor selectivity of catalytic hydrogenation methods via hydrogen. The same applies to the reduction of carbonyl compounds having a defined spatial configuration. In fact, the use of ordinary catalysts such as copperchromites, which only operate at elevated temperatures and pressures, leads to the reduction of the other functionalities present and in many cases, to a modification of the stereochemistry.
In the case of the reduction of unsaturated carbonyl compounds, only lithium aluminium hydride has the property of reducing at once aldehydes, ketones and esters in smooth reaction conditions, while being inert towards unsaturated carbon-carbon bonds eventually present in the molecule. Sodium borohydride or NaAlH.sub.2 (OCH.sub.2 CH.sub.2 function reduction, are weakly reactive towards esters. All these reagents, the use of which requires stoechiometric amounts, show the major drawback of being sensitive to moisture and air; furthermore, these reagents are very costly and pollutant, leading to the necessity of developping more economical and easier to handle systems.
It is noteworthy that the polymethyl-hydroxysilane (PMHS), which is defined by the following general formula: reduction of aldehydes to alcohols when in the presence of tin based No. 3,061,424!.
Grady and Kuivila (J. Org. Chem. 1969, 34, 2014) and Lipowitz and Bowman (Aldrichim. Acta 1973, 6, 1 and J. Org. Chem. 1975, 33, 162) have shown that, for the reducing system PMHS, the tin catalysis could be applied to the reduction of aldehydes and ketones, but not to that of esters into alcohols.
U.S. Pat. No. 5,220,020 describes a method for the preparation of alcohols by reduction of carbonyl compounds by means of a system constituted by a silanic reducing agent and a metal catalyst of formula actinide, whereas (L') to (L.sup.v) represent hydrogen, an alkyl, an aryl, a silyl, a halogen, or a radical --OR, --SR or --N R(R'), wherein R and R' are hydrogen, an alkyl or an aryl. Such a system could be applied to the reduction of esters, lactones, amides and imides.
Among the preferred catalysts, the patent above-cited mentions titane (IV) isopropylate and ethylate, as well as trichlorotitane (IV) isopropylate.
More recently Barr, Berk and Buchwald (J. Org. Chem. 1994, 59, 4323) have shown that the complex Cp.sub.2 TiCl.sub.2 reduced by butyllithium or ethylmagnesium bromide could catalyse the reduction of esters to the corresponding alcohols with good yields, but this technique requires expensive catalytic reagents, which are difficult to use on a large scale in the context of an industrial preparation.
DESCRIPTION OF THE INVENTION
We have now discovered that it was possible to prepare alcohols in good yields and in an economical way, by reduction of carbonyl derivatives such as aldehydes, ketones, esters and lactones, by means of polymethylhydroxysiloxane hydride, in the presence of a catalyst which can be prepared in situ or separately, from a metallic salt or complex and a reducing agent.
The process of the invention presents the advantage of employing inexpensive reagents, the use of which requires no particular precautions regarding protection against moisture or air. We have also ascertained that the reducing system of the invention does not lead to agglomeration or caking of the reaction medium, as opposed to what we were able to observe with the prior art systems.
The object of the present invention is therefore a process for the preparation of alcohols by reduction of the carbonyl function in substrates belonging to the class of aldehydes, ketones, esters or lactones, which may or m
REFERENCES:
patent: 3061424 (1962-10-01), Nitzsche et al.
patent: 4868345 (1989-09-01), Drent
patent: 5196601 (1993-03-01), Kitsuki et al.
patent: 5220020 (1993-06-01), Buchwald et al.
patent: 5227538 (1993-07-01), Buchwald et al.
S. Nitzsche et al., "Reducktionen mit Methyl-wasserstoff-polysiloxanen", Angewandte Chemie, vol. 69 (1957), p. 69.
G.L. Grady et al., "A Simple Technique for Performing Reactions with Organotin Hydrides", J. Org. Chem., vol. 6, No. 6 (1969), pp. 2014-2016.
J. Lipowitz et al., "Use of Polymethylhydrosiloxane as a Selective, Neutral Reducing Agent for Aldehydes, Ketones, Olefins, and Aromatic Nitro Compounds", J. Org. Chem., vol. 38, No. 1 (1973), pp. 162-165.
K. Barr et al., "Titanocene-Catalyzed Reduction of Esters Using Polymethylhydrosiloxane as the Stoichiometric Reductant", J. Org. Chem., vol. 59, No. 15 (1994), pp. 4323-4326.
S. Matlin et al., "An Immobilized Organotin Catalyst for Reduction of Ketones and Aldehydes", J. Chem. Soc., Chem. Commun., No. 12 (1984), pp. 798-799.
J. Boyer et al., "Reduction Selective de Composes Carbonyles par Catalyse Heterogene a la Surface des Sels", Tetrahedron, vol. 37 (1981), pp. 2165-2171.
J. Lopowitz et al., "The Use of Polymethylhydrosiloxane (PMHS) as as Reducing Agent for Organic Compounds", Aldrichim. Acata, 6, 1 (1973), pp. 1-6.
Boyer et al. "Reduction Selective de Composes Carbonyles par Catalyse Heterogene a la Surface des Sels", Tetrahedron, vol. 37, pp. 2165-2171, 1981.
Badio Barbara
Firmenich SA
Robinson Allen J.
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