Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-12-11
2002-07-16
Shaver, Paul F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S881000, C556S413000, C546S014000, C546S290000, C546S297000, C546S298000, C548S110000, C548S225000, C548S325100, C548S340100, C548S406000, C564S355000, C564S363000, C564S415000, C564S489000
Reexamination Certificate
active
06420613
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method of preparing reduced products of unsaturated organic compounds using a trichlorosilane. More specifically, the invention relates to a method of preparing reduced products by efficiently reducing unsaturated organic compounds in the presence of a particular ligand compound and, particularly, in the presence of an N-formylated product of an amine together with a trichlorosilane.
The invention further relates to a reducing agent comprising a particular silicon complex capable of efficiently reducing unsaturated organic compounds and, more particularly, to a reducing agent comprising a mononuclear or a binuclear silicon complex in which the coordination number of a silicon atom is 5 or 6.
BACKGROUND ART
The reducing reaction enables a hydrogen atom to react with an unsaturated bond only, and is a very important elementary reaction for synthesizing position-specific or stereospecific organic compounds.
In particular, secondary alcohol compounds such as 1-phenyl-1-ethanol, 2-butanol and 2-octanol are industrially important as intermediate products for dyes, perfumes and agricultural chemicals. A method of preparing the secondary alcohol compounds can be, represented by the one for reducing the ketone compounds with a reducing agent, and there have heretofore been developed many reducing agents and reducing reactions.
On the other hand, the trichlorosilane which is a very important compound as a starting material for industrially preparing highly pure polycrystalline silicon not only exhibits a reducing property but is also cheaply available and is easy to handle. In recent years, therefore, the trichlorosilane has ever been frequently used for the organic synthesis.
Under such circumstances, there has been known a method of reducing the ketone compounds to the secondary alcohol compounds by using the trichlorosilane in the presence of a dimethylformamide [Chemistry Letters, pp. 407-408, 1996].
According to the above method, however, a high yield is exhibited for the aralkyl ketone compounds but the yield is as low as 54% for the aryl ketone compounds. Therefore, the above reducing method cannot be said to be generally applicable. The reduction is not quite effected for the aliphatic ketone compounds.
It is therefore desired to develop a method of reducing unsaturated organic compounds and, particularly, reducing ketone compounds that are general applicabile by using a trichlorosilane that is cheaply available and is easy to handle.
DISCLOSURE OF THE INVENTION
In view of the above-mentioned circumstances, the present inventors have conducted a keen study and have discovered the fact that the unsaturated organic compounds are efficiently reduced when the reaction for reducing the unsaturated organic compounds is conducted by using a trichlorosilane in the presence of a particular ligand compound and, particularly, in the presence of an N-formylated product of a secondary amine having not less than 3 carbon atoms and, more particularly, in the presence of a formylated product of a cyclic amine such as pyrrolidine derivative or an N-formylated product of a secondary amine in which a carbon atom at the &bgr;-position of a nitrogen atom forms an oxo group.
That is, it is an object of the present invention to provide a method of preparing reduced products by efficiently reducing unsaturated organic compounds by using, as a reducing agent, a trichlorosilane that is industrially cheaply available and is easy to handle.
The invention further has an object of providing a reducing agent capable of efficiently reducing unsaturated organic compounds by using a trichlorosilane which is industrially cheaply available and is easy to handle.
According to the present invention, there is provided a method of preparing a reduced product of an unsaturated organic compound by mixing the unsaturated organic compound and a trichlorosilane together to reduce the unsaturated organic compound in the presence of a ligand compound which, when mixed together with the trichlorosilane, gives a signal at −15 to −120 ppm as measured by
29
Si-NMR at 74.9 MHz. Here, the ligand compound stands or a compound capable of being coordinated on the trichlorosilane.
In the above-mentioned method of preparation, it is desired that:
1. The ligand compound is the one capable of giving a signal at −15 to −120 ppm as measured by
29
Si-NMR at 74.9 MHz in a solution obtained by adding, into a solution of 0.2 mols of the trichlorosilane/liter, the ligand compound in an equimolar amount to the trichlorosilane and, particularly, an N-formylated product of a secondary amine having not less than 3 carbon atoms (and, particularly, a cyclic amine having not less than 3 carbon atoms or a secondary amine in which a carbon atom at the &bgr;-position of a nitrogen atom forms an oxo group); and
2. The unsaturated organic compound is at least the one selected from the group consisting of a ketone compound, an aldehyde compound and an imine compound.
According to the present invention, there is further provided a reducing agent comprising:
(a) a mononuclear silicon complex in which a silicon atom has a coordination number of 5, and among the five ligands coordinated on the silicon atom in the silicon complex, four ligands include a hydrogen atom and three chlorine atoms, and the remaining one ligand acts upon a trichlorosilane to form a stable silicon complex having five coordinations and/or,
(b) a binuclear silicon complex in which each silicon atom has a coordination number of 6, and among the six ligands coordinated on each silicon atom in the silicon complex, five ligands include a hydrogen atom and four chlorine atoms, and the remaining one ligand acts upon the trichlorosilane to form a stable silicon complex having five coordinations.
In the above reducing agent, it is desired that the ligand compound capable of forming a stable silicon complex having five coordinations upon acting on the trichlorosilane is:
1. The one capable of forming a silicon complex having five coordinations that can be detected when a solution is measured by
29
Si-NMR at 74.9 MHz, the solution being obtained by having the ligand compound acted on the trichlorosilane in an equimolar amount thereto in a solution of 0.2 mols of the trichlorosilane/liter;
2. The one that gives a signal at −25 to −120 ppm when a solution is measured by
29
Si-NMR at 74.9 MHz, the solution being obtained by adding, to a solution of 0.2 mols of the trichlorosilane/liter, the ligand compound in an equimolar amount to the trichlorosilane; and
3. An N-formylated product of a secondary amine having not less than 3 carbon atoms (and, particularly, an N-formylated product of a cyclic amine having not less than 3 carbon atoms or an N-formylated product of a secondary amine in which a carbon atom at the &bgr;-position of a nitrogen atom forms an oxo group).
The present inventors have studied the reduction reaction conducted in the presence of a trichlorosilane having a weak reducing power and various compounds by giving attention to the fact that even the same trichlorosilane exhibits different reducing power depending upon the kind of the compound that is also made present.
As a result, the inventors have discovered the fact that the reaction for reducing the unsaturated organic compound efficiently proceeds when a particular ligand compound is made present and, particularly, when an N-formylated product of the secondary amine having not less than 3 carbon atoms is made present together with the trichlorosilane.
The mechanism for efficiently conducting the reducing reaction has not yet be en clarified: in detail, but it is presumed that the trichlorosilane having a weak reducing power is transformed into active seeds of different activities depending upon the kind of the compound that is made present in the reaction system.
Here, the N-formylated product of the secondary amine having not less than 3 carbon atoms can be represented by, for example, the following general formula (I),
wherein R
Iwasaki Fumiaki
Matsumura Yoshihiro
Onomura Osamu
Tanaka Kenji
Shaver Paul F.
Sherman & Shalloway
Tokuyama Corporation
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