JPH0611750B2 - A novel method for producing optically active sulfoxides - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel method for producing optically active sulfoxides. More specifically, the present invention is extremely easy to produce an optically active substance of a sulfoxide having a vinyl group, which is useful as an intermediate or an optical resolving agent for synthesizing an optically active compound, in high purity and high yield. Industrially advantageous method.

Conventional technology Conventional, general formula As shown in the following, the sulfoxides in which two different substituents R and R ′ are bonded to the sulfoxide group are
It is known that there are two types of optical isomers, a (+)-form and a (-)-form in which a sulfur atom is an asymmetric atom.

By the way, an optically active sulfoxide in which R is an aryl group or an aralkyl group and R ′ is a vinyl group is, for example, p-toluenesulfinyl chloride + (-)-menthol ↓ (S)-(-)- Menthyl-(-)-p-toluenesulfinate ↓ + Vinylmagnesium bromide (R)-(+)-Vinyl-p-tolyl sulfoxide It is known that it can be synthesized by a process such as [Journal of・ Polymer Science Part A
-1 (Journal of Polymer Science Part A-1) "
Volume 8, pp. 2293-2308 (1970)].

However, this method has problems that it requires a very special reagent and includes a large number of steps that require complicated operations, and that the yield is low. It was inappropriate.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In view of such circumstances, an object of the present invention is to provide optically active isomers of sulfoxides having a vinyl group, which are useful as intermediates and optical resolving agents for synthesizing optically active compounds. Is to provide an industrial method for obtaining the above with high purity and high yield.

Means for Solving the Problems As a result of intensive studies by the present inventors, the racemic isomer of sulfoxides having a monohalogenated ethyl group was reacted with an optically active β-dinaphthol to give an inclusion compound. It was found that the above object can be achieved by performing a specific treatment, and the present invention has been completed based on this finding.

That is, the present invention has the general formula (In the formula, R ₁ is an aryl group or an aralkyl group, and R ₂ is a monohalogenated ethyl group), 1,1′-bi-
The optically active substance of 2-naphthol is reacted to form an inclusion compound of the optically active substance of the sulfoxides and the optically active substance of 1,1′-bi-2-naphthol. A general formula characterized in that dehydrohalogenation is carried out simultaneously with decomposition by treating with alkali. (Wherein R ₁ has the same meaning as described above), and a method for producing an optically active sulfoxide having a vinyl group.

The sulfoxides represented by the general formula (I) used in the method of the present invention are usually obtained as racemates. R _{1 in the} general formula (I) is a phenyl group, an aryl group such as a naphthyl group or an aralkyl group such as a benzyl group, and an aromatic ring contained in these groups is an alkyl group,
It may be substituted with an inert substituent such as an alkoxy group or a halogen atom. Further, R ₂ in the general formula (I) is an ethyl group having a halogenated α-position or β-position. As such sulfoxides, for example, R ₁ in the general formula (I) is a phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, etc., and R ₂ is an α-fluoroethyl group, β-fluoroethyl group. Examples thereof include sulfoxides such as a group, an α-chloroethyl group, a β-chloroethyl group, an α-bromoethyl group, and a β-bromoethyl group. Among these, particularly preferably those capable of optical resolution and dehydrohalogenation include sulfoxides in which R _{1 in the} general formula (I) is a m-substituted phenyl group and R ₂ is a chloroethyl group, for example, α -Chlorethyl-
Examples include m-tolyl sulfoxide and β-chloroethyl-m-tolyl sulfoxide.

On the other hand, the optically active form of 1,1′-bi-2-naphthol is known and can be easily obtained as a commercial product. This optically active 1,1′-bi-2-naphthol exists as two enantiomers, the (R)-(+)-form and the (S)-(-)-form, which have the following three-dimensional structures. To do.

The (R)-(+)-form and the (S)-(-)-form show diametric degrees of + 37.7 ° and −37.7 ° in tetrahydrofuran, respectively. , Any of these enantiomers can be used. And (R)-(+)-
When the body is used, this is selectively with the (-)-form of the sulfoxides and with the (S)-(-)-form, with the (+)-form of the sulfoxides. Combine to form a 1: 1 molar ratio of the inclusion compound.

According to the method of the present invention, sulfoxides and 1,1'-bi-
In order to form an inclusion compound with 2-naphthol, a racemate of a raw material sulfoxide is dissolved in a suitable solvent, and 1,1′-bi-2-naphthol is added thereto, and then at room temperature for several hours or several hours. Leave for 10 hours. In this case, heating or cooling may be carried out as desired in order to accelerate the dissolution of each raw material component or to accelerate the precipitation of the formed inclusion compound.

The amount of sulfoxides and 1,1′-bi-2-naphthol used is preferably about 1: 1 in terms of molar ratio, but either one may be used in excess if desired.

As the solvent, hexane, heptane, kerosene, aliphatic hydrocarbons such as petroleum ether, acetone, ketones such as methyl ethyl ketone, benzene, toluene, aromatic hydrocarbons such as xylene, diethyl ether,
Ethers such as dipropyl ether and tetrahydrofuran, alcohols such as methanol and ethanol, and esters such as ethyl acetate and butyl acetate are used. These may be used alone or in combination of two or more.

Next, the crystals of the clathrate compound precipitated as described above are separated by filtration and, if necessary, purified by recrystallization or the like, dissolved in a solvent, and then the solution is treated with a strong alkali, Decompose the clathrate compound to give 1,1'-bi-
At the same time as recovering the optically active substance of 2-naphthol, the halogenated ethyl group of the raw material sulfoxide can be dehydrohalogenated to obtain the optically active substance of the desired sulfoxide having a vinyl group.

The type and form of the strong alkali used in the method of the present invention is not particularly limited, but from the industrial viewpoint, 3 to 5 of lithium hydroxide, sodium hydroxide and potassium hydroxide is used.
An aqueous solution of 0% by weight, preferably 5 to 20% by weight is desirable.

EFFECTS OF THE INVENTION The method of the present invention is a method for industrially producing an optically active substance of a sulfoxide having a vinyl group. According to this method, the optically active substance of the sulfoxide can be extremely easily and highly purified with high yield. You get at a rate. The obtained optically active form of sulfoxides is highly reactive because it has a vinyl group, and is useful as a raw material for synthesizing an optically active compound or a raw material for an optically active polymer, and is also suitable as an optical resolving agent. is there.

EXAMPLES Next, the present invention will be described in more detail with reference to examples.

Example β-Chloroethyl-m-tolyl sulfoxide racemate
7.03 g and (R)-(+)-1,1'-bi-2-naphthol [[α]
_D + 37.7 ° (in THF)] 4.66 g was dissolved in 40 m of benzene and allowed to stand at room temperature for 12 hours, then precipitated (R)-
An inclusion compound consisting of 1 mol of (+)-1,1'-bi-2-naphthol and 1 mol of (-)-β-chloroethyl-m-tolylsulfoxide was collected by filtration and recrystallized three times with 50 m of benzene. After that, it is dried to give colorless prismatic crystals (melting point: 143-13.5).
C., [α] _D −73.8 ° (in ethanol)] 4.47 g was obtained. This crystal is dissolved in 50 m of benzene and 10 wt% NaO is added.
An aqueous solution of H (50 m) was added, and the mixture was stirred at room temperature for 12 hours. The benzene layer was washed well with water, dried and then benzene was distilled off to give (-)-vinyl-m-tolyl sulfoxide [[α] _D
-39.6 ° (in ethanol)] 1.31 g was obtained.

On the other hand, 3 wt% NaOH was added to the filtrate from which the inclusion compound was filtered off.
An aqueous solution was added to remove (R)-(+)-1,1'-bi-2-naphthol, and the solvent was distilled off to obtain 3.07 g of a residue.
Dissolve this in 50 m of benzene, then (S)-(-)-
1,1'-Bi-2-naphthol [[α] _D -37.7 ° (THF
Medium)] 3.97g was added and left at room temperature for 12 hours,
1 mole of (S)-(-)-1,1'-bi-2-naphthol and (+)-β-
An inclusion compound consisting of 1 mol of chloroethyl-m-tolyl sulfoxide was deposited. The inclusion compound was collected by filtration, recrystallized once with 50 m of benzene, and dried to obtain 4.73 g of colorless prism crystals [melting point: 138 to 141 ° C, [α] _D + 80.8 ° (in ethanol)]. It was When the crystals were treated with a 10 wt% NaOH aqueous solution, (+)-vinyl-m-tolyl sulfoxide [[α] _D + 39.2 ° (in ethanol)] 1.
41 g were obtained.

Claims (1)

[Claims] 1. A general formula (In the formula, R ₁ is an aryl group or an aralkyl group, and R ₂ is a monohalogenated ethyl group), 1,1′-bi-
The optically active substance of 2-naphthol is reacted to form an inclusion compound of the optically active substance of the sulfoxides and the optically active substance of 1,1′-bi-2-naphthol. A general formula characterized in that dehydrohalogenation is carried out simultaneously with decomposition by treating with alkali. (Wherein R ₁ has the same meaning as described above), and a method for producing an optically active sulfoxide having a vinyl group.