JPH0660114B2 - Optically active alcohol compound - Google Patents

Description

The present invention relates to a characteristic optically active alcohol compound, and more particularly to a 4-methyl-6-chloroalkanol compound having an asymmetric carbon.

Alcohol compounds having a methyl branch are useful as various industrial chemicals such as intermediate raw materials for cosmetics and medicines, and in particular, optically active alcohol compounds have recently attracted attention as intermediates for liquid crystal scientific substances. For example, alkoxyphenylpyrimidine compounds, alkoxybenzoic acid derivatives and the like are known as ferroelectric smectic liquid crystal chemical substances.

The alkoxy group in these liquid crystal compounds is 2
Alkoxy groups derived from alcohols having a relatively small number of carbon atoms such as -methylbutoxy and 6-methyloctoxy are known, but these compounds have a problem that the usable temperature range is not appropriate. , Was not satisfactory in practice.

As a result of repeated investigations on optically active alcohol compounds having a methyl branch, the present inventors have found that the compound represented by the following general formula (I) has excellent optical activity.

(In the formula, R represents a hydrogen atom or a linear alkyl group having 1 to 18 carbon atoms, and * represents an asymmetric carbon.) The optically active alcohol of the present invention is an important substance as an industrial chemical. For example, in addition to the above-mentioned intermediates for liquid crystal compounds, it is useful as an optical resolving agent or as an asymmetric synthesis aid, and various physiological activities are expected.

The present invention will be described in more detail below.

Examples of the alkyl group represented by R include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, hexadecyl and octadecyl groups.

Therefore, as the compound represented by the general formula (1),
6-chloro-4-methylhexanol, 6-chloro-4
-Methyloctanol, 6-chloro-4-methylnonanol, 6-chloro-4-methyldecanol, 6-chloro-4-methyldodecanol, 6-chloro-4-methyloctadecanol and the like can be mentioned.

These compounds are, for example, (R)-(+)-citronellic acid or (R) -2,6-obtained by alkylating the same.
A method for reducing dimethyl-8-oxoalkene-2, or an optically active 3,7-dimethyl-6-octenal or an optically active 2,6-obtained by alkylating the same.
The optically active 2,6-dimethyl-8-hydroxyalkene-2 obtained by the method of reducing dimethyl-8-oxoalkene-2 is chlorinated to give 2,6-dimethyl-8-chloroalkene-2.
Can be produced and then oxidized and reduced.

Hereinafter, the present invention will be specifically described with reference to examples. However, the invention is not limited by these examples.

Example 1 Synthesis of 6-chloro-4-methyloctanol (1) Synthesis of 2,6-dimethyl-8-hydroxydecene-2 18.2 g of optically active 2,6-dimethyl-8-oxodecene-2 in 50 m of ethanol Was dissolved in the solution, 19 g of sodium borohydride was added at room temperature over 5 minutes, and the mixture was stirred at room temperature for 2 hours.

After sufficiently concentrating the reaction mixture, 50 m of water was added, the mixture was extracted with diethyl ether, washed with saturated brine and dried. After distilling off the solvent, distillation was performed to obtain 15.5 g of 2,6-dimethyl-8-hydroxydecene-2 as a fraction having a boiling point of 79 to 80 ° C./1 mmHg.

(2) Synthesis of 2,6-dimethyl-8-chlorodecene-2 Dissolve 13.8 g of 2,6-dimethyl-8-hydroxydecene-2 in 75 m of carbon tetrachloride, add 21.0 g of triphenylphosphine, and reflux. Stir down for 3 hours. After distilling off the solvent, the mixture was extracted with hexane.
6.9 g of 2,6-dimethyl-8-chlorodecene-2 was obtained as a fraction of 120 ° C./16 mmHg.

(3) Synthesis of 6-chloro-4-methyloctanol 100 m each of anhydrous methanol and anhydrous dichloromethane was taken, and 6.9 g of 2,6-dimethyl-8-chlorodececene-2 was dissolved therein. This was cooled to −40 ° C. and oxygen containing 0.04 g / ozone was blown therein at a rate of 120 / hour for 30 minutes. After nitrogen gas was blown in to remove excess ozone, 4.2 g of sodium borohydride was added at the same temperature, the temperature was raised to room temperature over 1 hour, and the mixture was further stirred at room temperature for 1 hour.

After standing overnight, add 100 m of toluene to the reaction mixture and add 5% hydrochloric acid.
It was poured into 200 m and stirred at room temperature for 1 hour.

The toluene layer was collected, washed with saturated saline and then dried.
After distilling off toluene, it is distilled to give a boiling point of 69-70 ℃ / 0.1mmHg
As the distillate, 3.2 g of the target product, 6-chloro-4-methyloctanol, was obtained.

IR (cm ^-1 ) 3325 (s), 2900 (s), 1455 (s), 1380 (m), 1055 (s), 610
(m) H-NMR (CCl ₄ ) δ 4.03 (s; 1H, OH), 3.80 (m; 1H, CH-Cl), 3.43 (t, J = 6Hz; 2H, CH ₂ -O), 2.00- 1.06 (m; 9H, CH ₂ and CH), 0.96 (t, J = 6Hz; 3H, CH 3), 0.85 (d, J = 5Hz; 3H, CH 3) specific rotation [α] _{D =} + 0.75 ° (28 ° C., C = 1, CHCl ₃ solution) Example 2 Synthesis of 6-chloro-4-methylnonanol Instead of 2,6-dimethyl-8-oxodecene-2, an optically active 2,6
Example 1 except using -dimethyl-8-oxoundecene-2
By the completely same operation as described above, 6-chloro-4-methylnonanol, which was a target substance, was obtained as a fraction having a boiling point of 71 to 72 ° C./0.1 mmHg.

IR (cm ^-1 ) 3325 (s), 2950 (s), 1460 (s), 1380 (m), 1060 (s), 605
(m) H-NMR (CCl ₄ ) δ 4.00 (m; 1H, CH-Cl), 3.58 (t, J = 6Hz; 2H, CH ₂ -O), 2.77 (br-s; 1H, OH), 1.93 to 1.10 (m; 11H, CH ₂ and CH), 0.93 (t, d = 6Hz; 3H, CH ₃ ), 0.92 (d, J = 5Hz; 3H, CH ₃ ), specific rotation [α] _D = -1.75 ° (27 ° C, C = 2, CHCl ₃ solution) Example 3 Synthesis of 6-chloro-4-methylhexanol Instead of 2,6-dimethyl-8-oxodecene-2, an optically active 3,7
The title compound was synthesized in the same manner as in Example 1 except that -dimethyl-6-octenal was used. However, the target product was purified by silica gel column chromatography using ethyl acetate / n-hexane (25/75) as a developing solvent.

IR (cm ^-1 ) 3340 (s), 2925 (s), 1450 (s), 1380 (m), 1055 (s), 650
(m) H-NMR (CCl ₄ ) δ3.45 (t, J = 6Hz; 2H, CH ₂ -O), 3.45 (t, J = 6Hz; 2H, CH ₂ -Cl), 3.13 (s; 1H, OH), 2.00~1.10 (m; 7H , CH 2 and CH), 0.88) d, J = 5.5Hz; 3H, CH 3) specific rotation [α] _{D = -3.76 ° (27 ℃,} C = 2, CHCl ₃ solution)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication C07C 29/48 8930-4H 33/025 8930-4H

Claims (1)

[Claims] 1. An optically active alcohol compound represented by the following general formula (I). (In the formula, R represents a hydrogen atom or a linear alkyl group having 1 to 18 carbon atoms, and * represents an asymmetric carbon.)