CS261274B1 - 7-methyl-1-octine and method of its preparation - Google Patents

Abstract

7-Methyl-1-octine is prepared by reaction 1-bromo-5-methylhexane with lithium acetilide in dimethylformamide or by reaction of 1-bromo- -5-methylhexane with sodium acetylide in liquid ammonia or in a liquid mixture ammonia and dimethylformamide or in others dipolar aprotic solvents. 7-Methyl-1-octine is used for preparation 2-methyl-7,8-octadecin - a key intermediate in pheromone synthesis Great-headed Groom - disparlur.

Description

The present invention relates to 7-methyl-1-octine and to a process for its preparation.

Disparlur (cis-2-methyl-7,8-epoxyoctadecane), the sex pheromone of the broad-headed daisy (Portheria dispar L.), is one of the modern means for the comprehensive protection of forests against nun. Disparlur is, among others, prepared by methods of acetylene chemistry via the key intermediate 2-methyl-7,8-octadecin produced by the reaction of 1-bromo-7-methyloctane with 1-lithio-1-dodecin (Shamshurin AA, Rekhter MA, LA Government) : Khim, Prir Soedin, 9 (4), 545 (1973), Eiter, K .: Angew, Chem., 84 (2), 67 (1972). It has now been found (Jonas, J., Bacon, P., Humpa, O., Mazal, C .: Chem, leaves - ready to be sent to the editor) that 7-methyl-1-octin can be prepared and used to prepare 2-methyl- 7,8-octadecin with advantages for both overall yield and efficient purification.

According to the invention, 7-methyl-1-octin of the formula I has been found,

CH '3'

CH.

which makes it possible to prepare in a high yield and simply purify 2-methyl-7,8-octadecin, a key intermediate in the synthesis of the sex pheromone of the big-headed dwarf disparlure. The compound of formula I can be prepared by reacting 1-bromo-5-methylhexane with lithium acetylate in dimethylformamide or by reacting 1-bromo-5-methyldexane with sodium acetylide in liquid ammonia or in a mixture of liquid ammonia and dimethylformamide or dimethylsulfoxide or dimethylsulfoxide and tetrahydrofurane. in a mixture of tetrahydrofuran and dimethylformamide or a mixture of tetrahydrofuran and hexamethylphosphoric triamide.

Example 1

To a mixture of sodium acetylide and liquid ammonia, prepared by introducing acetylene into a solution of 13.5 g of sodium in 400 ml of liquid ammonia, 200 ml of dimethylformamide was added and 89.6 g of 1-bromo-5-methylhexane in 70 ml of dimethylformamide was added dropwise. The mixture was stirred for 1 hour, allowed to stand overnight, diluted with 1.5 L of water; the organic phase was separated, the aqueous phase was extracted with 3x150 ml of diethyl ether, the combined organic phases were dried over magnesium sulfate and distilled. It was thus obtained 45.3 g (72.2%) of 7-methyl-l-octyne (compound I), TV 39 to 41 ° C / 10 mm, n ²⁰ 1422 1. ^1H-NMR (C ² HC1 ₃₎ δ: 0.70 (d, 6H), δ 2.52 (s, 1H), δ 3.31 (t, 2H); IR spectrum: 3280, 2120, 630 cm

Example 2

To a mixture of lithium acetylide and diethyl ether, prepared by introducing acetylene into a solution of n-butyllithium (prepared from 10.7 g of lithium and 82.2 g of 1-bromobutane in 500 ml of diethyl ether), was added a solution of 107.5 g of 1-bromo-5- methylhexane in 350 ml of dimethylformamide, diethyl ether was distilled off under normal pressure, and the reaction mixture was stirred overnight. After diluting with 1.5 L of water, the organic layer was separated, the aqueous was extracted with 3x150 mL of petroleum ether, and the combined organic layers were dried over magnesium sulfate. Distillation yielded 40.0 g (53.4%) of 7-methyl-1-octine (compound of formula I), mp 49-50 ° C / 15 mm, η ² θ 1 421 8.

Claims (3)

SUBJECT OF THE INVENTION 7-Methyl-1-octin of formula I CH CH, CHCH, CH-CH, CH-CH, CH 2. A process for the preparation of a compound of formula (I) according to claim 1, wherein the 1-bromo-5-methylhexane is treated with sodium acetylide in liquid ammonia or a mixture of liquid ammonia and dimethylformamide or dimethylsulfoxide or dimethylsulfoxide and tetrahydrofuran or tetrahydrofuran; dimethylformamide or a mixture of tetrahydrofuran and hexymethylphosphoric triamide. 3. A process for the preparation of a compound of formula (I) according to claim 1, which comprises reacting 1-bromo-5-methylhexane with lithium acetylide in dimethylformamide.