DD227432A1 - METHOD OF PREPARING NEW 3-ARYL-3-ISOPROPYL-2,2-DIMETHYL-CYCLOPROPANCARBOXIC ACID ESTERS - Google Patents

Abstract

A process is described which allows to obtain formula-pure polysubstituted cyclopropanecarboxylic acid esters by the action of disintegrating diazoacetic acid ester on olefins obtained from a dialkylarylcarbinol by dehydration with the same alkyl group.

Description

Title of the invention

Process for the preparation of novel 3-aryl-3-isopropyl-2-dimethylcyclopropanecarboxylates

Field of application of the invention

The invention relates to a process for the preparation of novel substituted esters of cyclopropanecarboxylic acid, which can be used as intermediates for syntheses in organic chemistry or as potential fungicidal or insecticidal active ingredients.

Characteristic of the known technical solutions

It is known to prepare substituted cyclopropanecarboxylic acid esters from olefins by decomposition of diazoacetic acid ester (Coll. Czech Chem. Comraun. 24/1959/2460). In order to obtain cyclopropanecarboxylic acid esters which are required in a plurality of positions for further syntheses, structurally uniform olefins must be used The otherwise most suitable 2,2-dimethyl-substituted cyclopropanecarboxylic acid esters with further substituents in the 3-position, the synthesis is complicated by the fact that required for the starting material tri and tetrasubstituted olefins, the Wittig-Horner-Qlefinierung very difficult or completely impossible (A _# Mae reker in Org · Reactions, Vol · 14, 270/1965 /).

Target aer invention

The aim of the invention is to develop a production process with which multiply substituted cyclopropanecarboxylic acid esters are obtained via a clear reaction course without the formation of structural isomers.

Explanation of the essence of the invention

The object of the invention is a process for the preparation of novel S-aryl-S-isopropyl ^^ - dimethylcyclopropancarbonsäureestern the general formula IV, in which Ar is a phenyl- or substituted phenyl radical such as p-methylphenyl or p-chlorophenyl radical and R a Represent lower alkyl radical such as ethyl, by according to the invention a carbinol of the general formula I _# in the Ar has the abovementioned meanings, by elimination of water in an olefin of the general formula II in which Ar has the abovementioned meanings, then converting this olefin with a decomposing Diazoesaigsures the general formula III in which R has the abovementioned meaning, and then the resulting 3-Ary1-3-isopropyI-2,2-dimethyl-cyclopropancarbonsäureEeter IV isolated in a conventional manner.

+ N ₂ CH-COOR

Ar 'OOR III IV

Because the carbinol I has two isopropyl groups and an aryl group on the hydroxyl-bearing C atom, the main drawback of the known olefin syntheses by elimination of water from tertiary alcohols prepared by Grignard reaction, namely the multi-directional Wasserabspaitung bypassed by this choice of substituents. According to the invention, a structurally uniform olefin is always formed, which leads to the new target product by reaction with disintegrating diazoacetic acid ester. Thus, EjZ-cyclopropanecarboxylic esters having a defined position of the substituents on the C atoms of the cyclopropane ring are formed.

For the preparation of the carbinols, so the tertiary alcohols, for example, the easy to be carried out Grignard reaction between an aryl isopropyl ketone V and isopropyl Grignard reagent VI _- The reaction is very easy to carry out because the usual for the Grignard reactions solvent, such as diethyl ether or tetrahydrofuran, can be used and also with regard to the choice of the aryl substituent customary radicals, such as phenyl, p-tolyl or p-chlorophenyl, smoothly react · The reaction can be further simplified by starting from a Arylcarbonsäureester VII and by reaction with 2 moles of the isopropyl Grignard reagent in one step which produces carbinol ·

+ i-Pr-MgX

Ar O

VI

Ar ^N 0H

Ar-COOR * + 2 i-Pr-MgX VII VI

Since no complications can occur in the elimination of water from the carbinol I produced in this way, no restrictions are imposed with regard to the reaction conditions in the elimination of water. Usually one works with potassium bisulfate, but can also be used other dehydrating agents such as acetic anhydride without affecting the yield · By subsequent reaction with disintegrating Diazoessigsaureester the new 3-aryl-3 ~ isopropy1-2,2-dimethy1-cyclopropancarbonsäursester IV obtained »

Embodiment Example 1

27.6 g (150 mmol) of p-chlorophenyl-isopropyl ketone in 50 ml of diethyl ether are added with stirring to a solution of isopropyl magnesium bromide, which consists of 180 mmol of magnesium and 180 mmol of isopropyl bromide in 100% absolute. Diethyl ether was prepared, added dropwise. Then it is heated for 2 hours on the water bath. After cooling, the mixture is hydrolyzed by addition of ice and 50% aqueous ammonium chloride solution and the ethereal layer washed first with saturated bicarbonate solution, then with water. After drying over sodium sulfate obtained by distillation 24.7 g (72% d.Th,) p-chlorophenyl-diisopropylcarbinol, bp, _{Q 4} 90 to 92 ⁰ C.

10 g of this carbinol is added dropwise at 210 to 220 ^° C. and 150 torr to 6 g of molten potassium hydrogensulfate, during which time a mixture of isopropyl-2,2-dimethyl-1-phenylethylene and water is distilled off. After addition of 20 ml of ether, the layers are separated, the ethereal layer is dried and fractionated. This gives l-isopropyl-2,2-dimethyl-1-phenylethylene with a Sdp._ _Q 45 ⁰ C in 70% yield. The product is homogeneous by chromatography.

To 10.4 g (50 mmol) of this olefin and 0.8 g of copper powder is added dropwise with stirring at 130 ⁰ C, a solution of 25 mmol Diazoessigsäureethylester in 40 ml of dichloroethane so that the solvent distilled off slowly. After 30 minutes, the mixture is heated for a further 15 minutes to 140 to 150 ⁰ C and filtered after cooling from copper · At 1 Torr, the excess olefin is distilled off and the residue fractionated at 0.3 Torr. There are 3.8 g of 3-p-chlorophenyl-3

get isopropy1-2,2-dimethyl-cyclopropancarbonsäureethy! ester from Sdp.Q ₃₁₃₅ ⁰ C.

Example 2

Following the procedure of Example 1 is obtained from 150 mbar phenyl isopropyl ketone with 160 mmol Isopropylmagnesiumbromid in tetrahydrofuran uniform chromatography Phenyl diisopropylcarbinol in a yield of 81% d · Th, and a Sdp _egg 87 to 92 ⁰ C.

From .17.7 g of this carbinol (92 mmol) is obtained by boiling a mixture with 12 ml of acetic anhydride and a few drops of concentrated sulfuric acid for 11 hours 11 , 0 g of 1-isopropyl-2,2-dimethyl-l-phenylethylene from Sdp, _{Q Λ} 72 to 74 ⁰ C, which is converted by reaction with Diazoessigsäureethylester in 3-Isopropyl-2 _# 2-dimethyl-3-phenyl-cyclopropanecarboxylic acid ethyl ester · Sdp, _n _ 92 ⁰ C.

Example 3

From 100 mmol of p-bromophenyl-isopropyl ketone and 110 mmol of isopropylmagnesium bromide is obtained in an analogous to Example 1 procedure gas chromatographically uniform p-Brosnphenyl-diisopropylcarbinol in 85% yield with a sdp. _{N A} 110 to 112 ⁰ C, which is further to 1 -p-bromophenyl-1-isopropyl-2,2-dimethylethylene ₍ reacted and then cyclopropanated with ethyl diazoacetate *

Example 4

37.6 g (0 _t 25 mol) of ethyl benzoate in 50 ml of absolute # diethyl ether are added dropwise with stirring to 0.5 mol of isopropyl magnesium bromide in 200 ml of absolute. Diethyl ether. The mixture is then heated to boiling on the water bath for 3 hours. After cooling, it is hydrolyzed with ice and half-concentrated hydrochloric acid, the ethereal layer is separated, dried and distilled in vacuo to give 28 g

(58% d.Th ·) phenyl diisopropylcarbinol, bp. 84 ⁰ C,

0.6

which can be further processed according to the above examples to the S-isopropyl ^^ - dimethyl-S-phenyl-cyclopropanecarboxylic acid ester »

Claims (1)

invention claim Process for the preparation of novel 3-aryl-3-isopropyl-2,2-diethyl-cyclopropanecarboxylic acid esters of the formula IV OCR in the Ar is a phenyl or substituted phenyl radical such as p-methylphenyl or p-chlorophenyl radical and R is a lower alkyl radical such as ethyl radical, characterized in that a carbinol of the general formula I, in the Ar has the above meanings, by dehydration into an olefin of general formula II, II in the Ar dia has the above meanings, converted, this olefin then with a decaying Diazoessigsäureester the general formula III, N ₂ CH - COOR III in which R has the abovementioned meaning, and then the resulting 3-aryl-3-isopropyl 2,2-dimethyl-cyclopropanecarboxylic acid ester IV isolated in a conventional manner.