SU1694571A1 - Method of cyclopentene-2,3,-yl-@@@-acetic acid ethyl ester preparation - Google Patents

Abstract

The invention relates to unsaturated acid sugars, in particular the production of cyclopenten-2,3-yl-A-acetic acid ethyl ester, which is a juvenoid in relation to a grain grinder and a rice weevil. The goal is to increase the yield of the target product. For this purpose, 2-bromocyclo-pent-1-yl-L-acetic acid ethyl ester is boiled with a 2.5-2.8% excess bromide or lithium carbonate in dimethylformamide. These conditions increase the yield of the target product from 29 to 74% to 100% purity in 2.5 versus 18 hours in the known case.

Description

cl

WITH

The invention relates to a process for the production of cyclopent-2,3-yl-D l-acetic acid ethyl ester (I), which is a highly active juvenoid with respect to a grain grinder (pest suppression by 78%) and a rice weevil (suppression of offspring on 45%). The activity of ethyl ether (I) in relation to the rice weevil is 2.4 times greater than the activity of methoprene (one of the most active juvenoids) in relation to this pest.

A known method of producing ether (I) by metallizing cyclopentadiene (II) with metallic sodium and subsequent treatment of the metal derivative (III) with ethyl chloroacetate. The duration of the process 18h. The yield of the target ester (I) does not exceed 29%, calculated on cyclopentadiene (II).

Synthesis Scheme No

ABOUT

P

С1СНгСООС2Н5

+

I (29%)

", .L

СООС2Н5 (12%)

oh oh

4 01 4

The disadvantages of the known method for producing cyclopenten-2,3-yl-D-acetic acid ethyl ester are the low yield of the desired product (29%), the need to use metallic sodium to obtain the sodium derivative (III)

the formation of a side compound (IV), which requires additional costs for the purification and isolation of the target product.

The purpose of the invention is to simplify the process and increase the yield of the target product.

This goal is achieved by using as synthon to obtain ethyl ester (I) ethyl ester of 2-bromocyclopenta-1-yl-D-acetic acid (V), which is boiled with a 2.5-2.8-fold molar excess lithium carbonate and lithium bromide in dimethylformamide. Carbonate and lithium bromide are used in a 1: 1 ratio. Sinton (V) is obtained from unsaturated ester (VI) in 2 hours in 95% yield. Ether (VI) is obtained from cyclopentanone in 74% yield and 100% purity in 2-2.5 h.

Synthesis Scheme:

MejSiCHjCOjjEl

CO, El

ex vi

CO, E1

V

BP

soosgn5 LiBl.iLizcoj

DMF

COOC2H5

-ex

I

The proposed method allows to increase the yield of the target product to 95%, to simplify the process by reducing the duration of the process to 6-6.5 hours versus 18 hours in the prototype and eliminating the use of a fire-hazardous alkali metal, sodium. In addition, in the course of the reaction, difficult-to-release by-products are not formed.

Example 1. 2.53 g (1.52 mmol) of bromide (V), 3.7 g (4.3 mmol) of lithium bromide and 3.2 g (4.3 mmol) are boiled (153 ° C) for 2 hours. ) lithium carbonate in 84 ml of absolute dimethylformamide (2.8 molar excess of ZIBr and ZICOs). The reaction mixture is cooled, diluted with ether and washed successively with 0.4N. HCI with saturated solutions of NaHCOa, NaCI, dried with MgS04 and evaporated. In the residue, 2.26 g of product is obtained, which is distilled in vacuo, and 2.18 g (95%) of dienoate (I) is obtained, b.p. 95-100 ° С (1 mm Hg), 20 ~ 1.4845 each.

IR spectrum (g), 860 cf. 1130s, 1210s, 1670sr, 1700s.

UV spectrum (v) 265 (16660) nm.

PMR spectrum (d), ppm: 1.27 (t. CH3 CH20, J = 7 Hz); 2.57-2.98 (m. 4H, CH2); 4.15 (sq. 2H, CH20); 5.77 (m. 1 H,); 6.3 (m. 1 H,); 6.58 (m. 1H,).

Mass spectrum (m / z, J),%: 152 M + (80), 124 (19), 107 (81.2), 79 (100).

Example 2. 2.53 g (1.52 mmol) of synthon (V), 3.3 g (3.8 mmol) of lithium bromide and 2.86 g (3.8 mmol) of lithium carbonate in 85 are boiled for 2 hours. ml of absolute dimethylformamide (molar excess of 2.5) and after treatment in Example 1, 2.16 g (94.5%) of dienoate is obtained

()

PrimerZ (comparative). Boil 2 hours 3.53 g (1.52 mmol) of synthon (I). 3.96 g (4.56 mmol) of lithium bromide and 3.43 g (4.56 mmol) of lithium carbonate in 85 ml of absolute dimethylformamide (molar excess 3) and after

The treatments of Example 1 give 2.18 g (95%) of the dienoate (I).

Example 4 (comparative). 2 t 3.53 g (1.52 mmol) of synthon (V), 2.64 g (2.99 mmol) of lithium bromide and 2.3 g (2.99 mmol) are boiled

lithium carbonate in 85 ml of absolute dimethylformamide (molar residue 1.9) and after treatment in Example 1, 2.07 g (90%) of dienoate (I) is obtained.

Example 5 (comparative). Kip t

1.5 hours 3.53 g (1.52 mmol) of synthon (V), 3.3 g (3.8 mmol) of lithium bromide and 2.86 g (3.8 mmol) of lithium carbonate in 85 ml of absolute dimethylformamide and after processing in example 1, 0.5 g of the original synthon (V) is obtained and

1.6 g (70%) of dienoate (I).

Example 6 (comparative). Boiling point 2.5 hours 3.53 g (1.52 mmol) of synthon (V). 3.3 g (3.8 mmol) of lithium bromide and 2.86 g (3.8 mmol) of lithium carbonate in 85 ml of absolute dimethylformamide and after the treatment in example 1, 1.9 g (82%) of dienoate (I) are obtained.

Example 7 (comparative). 2 t 3.53 (1.52 mmol) synthon (V), 3.7 g (4.3 mmol) lithium bromide and 2.86 g (3.8 mmol) boil

lithium carbonate in 85 ml of absolute dimethylformamide and after treatment in example 1, 2.1 g (92%) of dienoate (I) are obtained.

Example 8 (comparative). Boil 2 hours 3.53 g (1.52 mmol) of synthon (V), 3.3 g (3.8

0 mmol) of lithium bromide and 3.2 g (4.3 mmol} of lithium carbonate in 85 ml of absolute dimethylformamide, and after treatment in Example 1, 2.08 g (91%) of dienoate (I) is obtained. Example 9 (comparative). Kip t t

5 2 h 3.53 - g (1.52 mmol) of synthon (V), 3.5 g (4.03 mmol) of lithium bromide and 2.9 g (3.9 mmol) of lithium carbonate in 85 ml of absolute dimethylformamide and after treatment in example 1 get 2.16 g (94.5%) of dienoate ()

Claims (1)

The invention of the duct, 2-bromo-cyclopent-1 ethyl ester A process for the preparation of ethyl cyclyl-A-acetic acid ethyl ester is subjected to boiling lopentene-2, 3-yl-A-acetic acid, for example, from 2.5 to 2 , 8-fold molar It is understood that, in order to simplify the excess bromide and lithium carbonate in the preprocess, increase the yield of the target prod e dimethylformamide.