JP2002308885A - Catechol metal compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catechol metal compound useful as a Lewis acid catalyst, etc., such as a catalyst for cleavage of ether bonds. SOLUTION: The compound or its salt is represented by formula (I) [wherein X<1> -X<4> are each a hydrogen atom, a halogen atom or the like, provided that at least one of X<1> to X<4> is a halogen atom; M is a boron atom, an aluminum atom, a titanium atom or the like; Y<1> and Y<2> are each a halogen atom, a (non) substituted aryl group or the like (provided that Y<1> and Y<2> are not simultaneously a halogen atom); and n is 0 or 1].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a novel catechol metal compound or a salt thereof.

[0002]

2. Description of the Related Art Catechol metal compounds useful in the field of organic synthesis reactions are known. For example, as catechol metal compounds useful for hydroboration, catecholborane, 4,5,6,7-tetrachloro-1,
3,2-benzodioxoborolanes are known. In addition, the following compounds are known as catechol metal compounds other than the above (where Hal represents a fluorine atom, a chlorine atom, or a bromine atom).

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[0003]

An object of the present invention is to provide a catechol metal compound useful in the field of organic synthesis reactions. In particular, it is an object of the present invention to provide a catechol metal compound useful as a Lewis acid catalyst such as a catalyst for an ether bond cleavage reaction. The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have succeeded in providing a compound represented by the following general formula (I), and have completed the present invention.

That is, the present invention provides the following general formula (I):

Embedded image ^{(Wherein, X 1, X 2, X} 3, and X ⁴ each independently represent a hydrogen atom, a halogen atom, a nitro group, a cyano group, a sulfonyl group, an alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted Represents a substituent selected from the group consisting of an arylalkyl group, provided that at least one of X ¹ , X ² , X ³ , and X ⁴ is selected from the group consisting of a halogen atom, a nitro group, a cyano group, and a sulfonyl group Substituents;
M represents an atom selected from the group consisting of a boron atom, an aluminum atom, a gallium atom, an indium atom, a titanium atom, and a zirconium atom; Y ¹ and Y ² each independently represent a halogen atom, a substituted or unsubstituted aryl group,
An alkoxy group, a substituted or unsubstituted aryloxy group, a mono- or dialkylamino group, an alkylthio group, and a substituent selected from the group consisting of substituted or unsubstituted arylthio groups, provided that Y ¹ and Y ² are simultaneously a halogen atom N represents 0 or 1) or a salt thereof. According to a preferred aspect of the present invention, there is provided the compound or a salt thereof, wherein M is a boron atom.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The terms used in the present specification have the following meanings. The alkyl moiety of the alkyl group or a substituent having an alkyl moiety (such as an arylalkyl group, an alkoxy group, a mono- or dialkylamino group, or an alkylthio group) may be linear, branched, cyclic, or a combination thereof. Whichever
The carbon number is 1 to 12, preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and particularly preferably about 1 to 4. Examples of the alkyl group include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a cyclopropyl group, a n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a cyclobutyl group,
Examples thereof include a cyclopropylmethyl group, an n-pentyl group, and an n-hexyl group, but are not limited thereto.

The halogen atom may be any of a fluorine, chlorine, bromine or iodine atom, but is preferably a fluorine, chlorine or bromine atom. When "substituted or unsubstituted" is used for the aryl moiety of an aryl group or a substituent having an aryl moiety (eg, an arylalkyl group), the aryl ring may have one or more substituents on the ring Means that. The position of the substituent present on the aryl ring is not particularly limited, and when two or more substituents are present,
They may be the same or different. Examples of the aryl moiety of the aryl group or a substituent having an aryl moiety (such as an arylalkyl group) include a phenyl group or a naphthyl group, and more preferably a phenyl group.

[0007] Examples of the substituted aryl group include an alkyl-substituted aryl group, more preferably an alkyl-substituted phenyl group. More specifically, examples of the substituted aryl group include a p-toluyl group, a p-ethylphenyl group, and a xylyl group. Examples of the arylalkyl group include a benzyl group, a phenethyl group, and a naphthylmethyl group, and a benzyl group is preferable.

M is an atom selected from the group consisting of a boron atom, an aluminum atom, a gallium atom, an indium atom, a titanium atom, and a zirconium atom, preferably a boron atom or an aluminum atom, particularly preferably a boron atom. . n represents 0 or 1 depending on the valence of the metal represented by M. X ¹ , X ² , X ³ or X ⁴ is preferably an electron-withdrawing group, and as the electron-withdrawing group, for example, a chlorine atom or a bromine atom can be mentioned as preferable examples. ^{X 1, X 2, X 3} , or it is particularly preferred that at least one of X ⁴ is an electron withdrawing group.

The alkoxy group represented by Y ¹ or Y ² includes
Examples include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group and the like, and examples of the aryloxy group include a phenoxy group. Examples of the mono or dialkylamino group represented by Y ¹ or Y ² include a monomethylamino group, a dimethylamino group, a monoethylamino group, an ethylmethylamino group, a mono-n-propylamino group, and the like. When they have groups, they may be the same or different. The Y ¹ or Y ² is an alkylthio group indicated and the like can be illustrated a methylthio group, an ethylthio group, arylthio group and the like phenylthio group. As Y ¹ or Y ² , a methoxy group, an ethoxy group, an n-propoxy group, an n-
An alkoxy group such as a butoxy group, an aryloxy group such as a phenoxy group, or an arylalkyl group such as a benzyl group is preferable, and an alkoxy group is particularly preferable.

Specific examples of the compound represented by the above general formula (I) include, for example, 3,4,5,6-tetrachlorocatecholbutoxyborane, 3,4,5-trichlorocatecholbutoxyborane, 3,4 3,6-dichlorocatecholbutoxyborane, 3,4-dichlorocatecholbutoxyborane, 3,5-dichlorocatecholbutoxyborane, 3,6-dichlorocatecholbutoxyborane, 3-
Chlorocatechol butoxyborane, 4-chlorocatechol butoxyborane, and the chlorine atom (2
A compound in which, if it has more than one chlorine atom, a part or all of them are replaced by a fluorine atom or a bromine atom, and a compound in which the butoxy group of the above compound is replaced by an alkoxy group, an alkylamino group, or an alkylthio group ;

3,4,5,6-tetracyanocatechol borane, 3,4,5-tricyanocatechol borane,
On the boron atom of 3,4,6-tricyanocatechol borane, 3,4-dicyanocatechol borane, 3,5-dicyanocatechol borane, 3,6-dicyanocatechol borane, 3-cyanocatechol borane, 4-cyanocatechol borane A compound wherein the hydrogen atom of is replaced by an alkoxy group, an alkylamino group, or an alkylthio group;

3,4,5,6-tetranitrocatechol borane, 3,4,5-trinitrocatechol borane,
On the boron atom of 3,4,6-trinitrocatechol borane, 3,4-dinitrocatechol borane, 3,5-dinitrocatechol borane, 3,6-dinitrocatechol borane, 3-nitrocatechol borane, 4-nitrocatechol borane Compounds in which the hydrogen atom is replaced with an alkoxy group, an alkylamino group, or an alkylthio group; and compounds in which the boron atom of all of the above compounds is replaced with an aluminum atom, a gallium atom, an indium atom, a titanium atom, or a zirconium atom. Can be mentioned.

Of these, an alkoxy derivative of tetrachlorocatechol borane or an alkoxy derivative of tetrabromocatechol borane is preferred. However, the compound represented by the general formula (I) is not limited to the compounds exemplified above.

The compound represented by the above general formula (I) can be produced, for example, by reacting catechol with a corresponding alkoxy compound or alkylthio compound. Specific examples thereof are specifically shown in Examples of the present specification, and those skilled in the art can refer to the methods described in the Examples,
By appropriately selecting starting compounds, reaction reagents, reaction conditions, and the like, any of the compounds included in the above general formula (I) can be produced.

The compound represented by the above general formula (I) may have one or more asymmetric carbons depending on the kind of the substituent, and may have stereoisomers such as optically active isomers and diastereoisomers. May be present. The scope of the present invention includes the stereoisomers in pure form as well as any mixture of the stereoisomers, and any substance such as a racemate. Further, the compound represented by the general formula (I) may form a salt, and the compound represented by the general formula (I) or a salt thereof may form a hydrate or a solvate. However, these are included in the scope of the present invention.

The compound of the present invention or a salt thereof can be used, for example, in the field of organic synthesis. For example, it can be used as a Lewis acid catalyst such as a catalyst for an ether bond cleavage reaction. However, the use of the compound of the present invention or a salt thereof is not limited to the use in the ether cleavage reaction or the field of organic synthesis.

[0017]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the scope of the present invention is not limited to the following examples. In the examples, the borane compound was identified by mass spectrometry (MS: TSQ manufactured by Finnigan Mat).
-700). In addition, the quantitative determination of the terminal group was calculated by dissolving the sample in CDCl ₃ and calculating the integrated value of an NMR spectrum (270 MHz, measured by JEOL Ltd.).

Example 1: Synthesis of (3,4,5,6-tetrachlorocatechol) butoxyborane 0.62 g (2.5 mmol) of 3,4,5,6-tetrachlorocatechol in a two-necked eggplant flask purged with nitrogen. Was dissolved in 20 ml of toluene. 0.58 g (2.5 mmol) of tributoxyborane was added to react, and toluene was distilled. The remaining toluene was distilled off under reduced pressure to obtain 0.83 g (2.5 mmol) of light yellow solid tetrachlorocatechol borane. As a result of mass spectrometry,
A molecular ion peak m / z: 328 (M ⁺ ·) was observed.

Example 2: Cleavage reaction of 2-methyltetrahydrofuran The dried branch flask was purged with nitrogen, and 1 mmol of 3,4,5,6-tetrachlorocatecholbutoxyborane synthesized in Example 1 and 20 ml of degassed and dried toluene were added. added. After 1.2 mmol of dried tetrabutylammonium bromide was added thereto, 1 mmol of 2-methyltetrahydrofuran degassed and dried and purified was added, and the mixture was stirred at room temperature. After 6 hours, a portion of the contents was extracted and the proton NM
When R was measured, 4-hydroxy-
It was confirmed that 1-bromopentane was produced.
This means that the oxygen-C5 carbon of the tetrahydro ring was selectively cleaved.

Example 3 (Comparative Example) Butoxy (catechol) borane was synthesized in the same manner as in Example 1 except that catechol was used instead of 3,4,5,6-tetrachlorocatechol. Next, the above-mentioned butoxy (catechol) borane was used in place of 3,4,5,6-tetrachlorocatecholbutoxyborane in Example 2, and the ether cleavage reaction of 2-methyltetrahydrofuran was carried out in the same manner as in Example 2 except for the above. Attempted, but no reaction proceeded.

[0021]

The compound of the present invention or a salt thereof is useful as a Lewis acid catalyst such as a catalyst for an ether bond cleavage reaction.

Claims (2)

[Claims] 1. The following general formula (I): (Wherein X ¹ , X ² , X ³ , and X ⁴ each independently represent a hydrogen atom, a halogen atom, a nitro group, a cyano group, a sulfonyl group, an alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted Represents a substituent selected from the group consisting of an arylalkyl group, provided that at least one of X ¹ , X ² , X ³ , and X ⁴ is selected from the group consisting of a halogen atom, a nitro group, a cyano group, and a sulfonyl group Substituents;
M represents an atom selected from the group consisting of a boron atom, an aluminum atom, a gallium atom, an indium atom, a titanium atom, and a zirconium atom; Y ¹ and Y ² each independently represent a halogen atom, a substituted or unsubstituted aryl group,
Alkoxy group, a substituted or unsubstituted aryloxy group, a mono- or dialkylamino group, an alkylthio group, and a substituted group selected from the group consisting of substituted or unsubstituted arylthio group, provided that Y ¹ and Y ² is a halogen atom at the same time N represents 0 or 1) or a salt thereof. 2. The compound according to claim 1, wherein M is a boron atom, or a salt thereof.