New 2,2-dimethylcyclopropanecarbaldehyde dimethyl acetal derivatives of the formula ##STR1## wherein X is --CH.sub.2 OC(O)CH.sub.3, --CH.sub.2 OH, or --CHO are useful chemical intermediates for the preparation of pesticidally active cyclopropanecarboxylates.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to new 2,2-dimethylcyclopropanecarbaldehyde dimethyl 
acetal derivatives and to a process for the preparation of these 
derivatives. 
2. Description of the Prior Art 
It is well known that certain substituted cyclopropanecarboxylic acid 
derivatives are an important class of pesticides called "pyrethroids". 
These pyrethroids have been of considerable interest because of their 
quick knock-down activity, low persistence as toxic residues and their low 
mammalian toxicity. However, the acid moiety of these pyrethroids has 
heretofore been fairly expensive to manufacture in the large scale 
commercial quantities for agricultural and domestic applications. 
The hereinafter described process of the invention, and the new 
intermediates thereof, provide a method for obtaining desired pyrethroids 
from 3-carene, which is an inexpensive, readily available, naturally 
occurring terpene found in numerous varieties of pine trees. 
SUMMARY OF THE INVENTION 
The present invention is directed to new 
2,2-dimethylcyclopropanecarbaldehyde dimethyl acetal derivatives of 
formula I 
##STR2## 
wherein X is --CH.sub.2 OC(0)CH.sub.3, --CH.sub.2 OH or --CHO, useful as 
intermediates for the preparation of certain pesticidally active 
cyclopropanecarboxylates of the "pyrethroid" type, and to a process for 
the preparation of the acetal derivatives of formula I. 
One specific embodiment of the invention is 
3-acetoxymethyl-2,2-dimethylcyclopropanecarbaldehyde dimethyl acetal of 
formula II 
##STR3## 
This compound is prepared by ozonolysis of the corresponding 
2-(3-acetoxymethyl-2,2-dimethylcyclopropyl)vinyl acetate of formula X 
followed by reduction of the ozonolysis product formed in the presence of 
a lower alkanol, such as methanol, ethanol or the like, and in the 
presence of an acetalizing catalyst such as p-toluenesulphonic acid. The 
reduction is suitably carried out using dimethyl sulphide. 
Ozonolysis of organic compounds and reduction of the peroxidic ozonolysis 
products formed is described in, for example, Chemical Reviews 58 (1958) 
925-995. 
The acetal of formula II above is converted into 
3-(hydroxymethyl)-2,2-dimethylcyclopropanecarbaldehyde dimethyl acetal of 
formula III 
##STR4## 
by hydrolysis under conditions in which the two methoxy groups remain 
unchanged. Hydrolysis of esters is described in, for example, "Methoden 
der Organischen Chemie" (Houben-Weyl), Volume VIII (1952) 418-423 and 
638-639. In the present case, this hydrolysis can be achieved by using an 
alkaline-reacting medium. 
The compound of formula III is a new chemical and a useful intermediate. 
Oxidation of the compound of formula III under conditions suitable for the 
conversion of a primary alcohol to an aldehyde produces 
3-formyl-2,2-dimethylcyclopropanecarbaldehyde dimethyl acetal of formula 
IV 
##STR5## 
which is also a new chemical and useful intermediate. The oxidation of 
primary alcohols to aldehydes is described in, for example, "Methoden der 
Organischen Chemie" (Houben-Weyl), Volume VII, Part 1 (1954) 159-192. The 
oxidation is suitably carried out with the chromium trioxide-pyridine 
complex, as described in J. Org. Chem. 35 (1970) No. 11, 4000-4002. 
The above described compound of formula IV is a useful chemical 
intermediate and is converted into a compound of formula V 
##STR6## 
wherein each Hal is independently selected from chlorine, bromine or 
fluorine, by a two step process described in British patent application 
52466/77, filed Dec. 16, 1977, in Great Britain and its corresponding U.S. 
application Ser. No. 966,681 of Pieter A. Verbrugge, Petrus A. Kramer, 
Johannes Van Berkel and Hendrik C. Kelderman, filed concurrently with the 
present application. This process comprises treating a 
tri(dialkylamino)phosphine or an alkyl ester of an ortho-phosphorous acid 
bis(dialkylamide) with a compound generating a dihalocarbene :C(Hal).sub.2 
in which Hal has the same meaning as defined above and, after the reaction 
has proceeded virtually to completion, treating the resulting product with 
a compound of formula IV. 
Hydrolysis of the compound of formula V followed by oxidation of the 
resulting aldehyde product yields 
2-(2,2-dihalovinyl)-3,3-dimethylcyclopropanecarboxylic acids, which are 
used to prepare pyrethroid esters of the type described in U.S. Pat. No. 
4,024,163 using procedures disclosed therein. 
As stated earlier, the new compounds of the invention are part of a new 
pyrethroid synthesis route starting from 3-carene. Accordingly, the 
intermediate X is prepared by a multi-step process in which 3-carene, 
having the formula VI 
##STR7## 
is ozonized to form 
1-(2,2-dimethoxyethyl)-2,2-dimethyl-3-(2-oxopropyl)cyclopropane of formula 
VII 
##STR8## 
which is oxidized with a strong oxidizing agent, such as 
m-chloroperbenzoic acid, to 
(2-(2,2-dimethoxyethyl)-3,3-dimethylcyclopropyl)methyl acetate of formula 
VIII 
##STR9## 
which is hydrolyzed in the presence of acid to 
(2,2dimethyl-3-(2-formylethyl)cyclopropyl)methyl acetate of formula IX 
##STR10## 
and this compound is treated with acetic anhydride in the presence of a 
base to yield the compound of formula X. 
The compounds of formulas II thru X, inclusive, may have a cis or trans 
structure or may be a mixture of such isomers, a pure optical isomer or a 
mixture of optical isomers. When (+)-3-carene is the starting material, 
the products have predominately the cis-form. 
The above described compounds VII, VIII, IX and X, and their preparation, 
are described and claimed in the concurrently filed U.S. patent 
application, Ser. No. 953,987 of Steven A. Roman.

ILLUSTRATIVE EMBODIMENTS 
The following embodiments serve to further illustrate the invention. Yields 
and purities were determined by means of gas-liquid chromatography and 
nuclear magnetic resonance (NMR) spectroscopy. The NMR data quoted were 
recorded at 90 MHz using solutions of the compounds in deuterochloroform. 
EMBODIMENT 1 
1-(2,2-dimethoxyethyl)-2,2-dimethyl-3-(2-oxopropyl)cyclo propane (the 
compound of formula VII) 
A flask was charged with (+)-3-carene (375 mmol) and water-free methanol 
(150 ml) and kept at a temperature of -60.degree. C. Then, a mixture of 
ozone and oxygen was passed through the liquid in the flask at a rate of 
70 1/h (corresponding to 75 mmol of ozone per hour) until the (+)-3-carene 
was fully converted (5 hours). The reaction mixture was allowed to react a 
temperature of 20.degree. C., dimethyl sulphide (750 mmol) and p-toluene 
sulphonic acid (1.74 mmol) were added and the resulting mixture was 
stirred for four days at 20.degree. C. At the end of this period, the 
(+)-3-carene was fully converted into the desired product. Methanol and 
dimethyl sulphide were evaporated from the reaction mixture at a pressure 
of 24 mbar (40.degree. C.), diethyl ether (150 ml) was added to the 
residue obtained, the solution formed was washed with 5%w aqueous sodium 
hydrogen carbonate (30 ml) and with four 30 ml portions of water, the 
washed solution was dried over anhydrous magnesium sulphate, and the 
solvent was evaporated from the dried liquid at a temperature of 
30.degree. C. and a pressure of 24 mbar to give a liquid residue (68.9 g). 
This residue was distilled at 83.degree. C./1 mbar to give a fraction 
consisting of the cis isomer of the desired product, yield 73.5%. 
EMBODIMENT 2 
(2-(2,2-Dimethoxyethyl)-3,3-dimethylcyclopropyl)methyl acetate (the 
compound of formula VII) 
The contents of a flask charged with the product as prepared in Embodiment 
1 above (200 mmol), chloroform (300 ml) and m-chloroperbenzoic acid (384 
mmol) were stirred at 20.degree. C. for 24 hours. The mixture was 
separated by filtration, the precipitate was washed with n-pentane (150 
ml), the combined filtrates were washed with two 50 ml portions of water, 
the washed liquid was dried over anhydrous magnesium sulphate, and the 
solvent was evaporated from the dried liquid at a temperature of 
90.degree. C. and a pressure of 20 mbar to give a residue containing the 
desired product in a yield of 97%. The content of the desired product in 
the residue was 92%; only the cis isomer had been formed. 
EMBODIMENT 3 
(2,2-Dimethyl-3-(2-formylethyl)cyclopropyl)methyl acetate (the compound of 
formula IX) 
The contents of a flask charged with the product in the residue prepared in 
Embodiment 2 above (218 mmol), acetic acid (40 ml) and water (20 ml) were 
stirred at 60.degree. C. during 2.5 hours. The solvent was evaporated from 
the reaction mixture at a temperature of 45.degree. C. and a pressure of 
24 mbar, the residue obtained was taken up in diethyl ether (150 ml), the 
solution obtained was washed with two 50 ml portions of a 5%w solution of 
sodium hydrogen carbonate in water and with two 50 ml portions of water, 
the washed solution was dried over anhydrous magnesium sulphate, and the 
solvent was evaporated from the dried liquid at a temperature of 
30.degree. C. and a pressure of 24 mbar to give a residue containing the 
desired product in a yield of 80%; the content of the desired product in 
the residue was 85%. Only the cis isomer had been formed. 
EMBODIMENT 4 
2-(3-Acetoxymethyl-2,2-dimethylcyclopropyl)vinyl acetate (the compound of 
formula X) 
The contents of a flask charged with the product in the residue prepared in 
Embodiment 3 above (175 mmol), triethylamine (386 mmol) and acetic 
anhydride (350 ml) were stirred at 20.degree. C. for 18 hours. The solvent 
was evaporated from the reaction mixture at a temperature of 70.degree. C. 
and a pressure of 20 mbar, the residue obtained was taken up in diethyl 
ether (150 ml), the solution obtained was washed with five 40 ml portions 
of water, the solution was dried over anhydrous magnesium sulphate, and 
the solvent was evaporated from the dried liquid at a temperature of 
40.degree. C. and a pressure of 20 mbar to give a residue containing the 
desired product in a quantitative yield. The content of the desired 
product in the residue was 88.4%; 64% of the desired product had the cis 
structure, 36% the trans structure on the carbon-carbon double bond. The 
orientation to the cyclopropane ring was still cis. 
EMBODIMENT 5 
3-Acetoxymethyl-2,2 -dimethylcyclopropanecarbaldehyde dimethyl acetal (the 
compound of formula II) 
A flask was charged with the product in the residue prepared in Embodiment 
4 above (175 mmol), water-free methanol (200 ml) and p-toluenesulphonic 
acid (1.16 mmol) and kept at a temperature of -65.degree. C. Then, a 
mixture of ozone and oxygen was passed through the liquid in the flask at 
a rate of 60 l/h (corresponding to 75 mmol of ozone per hour) until the 
starting material was fully converted (2.5 hours). The reaction mixture 
formed was allowed to reach a temperature of 20.degree. C., dimethyl 
sulphide (350 mmol) was added, and the mixture formed was stirred for 17 
hours at 20.degree. C. Methanol and dimethyl sulphide were evaporated from 
the reaction mixture at a pressure of 16 mbar, diethyl ether (50 ml) was 
added to the residue obtained and sufficient saturated aqueous solution of 
sodium bicarbonate was added to the mixture so that the pH reached a value 
of 7. Then, the mixture was washed with three 50 ml portions of water, the 
washed liquid was dried over anhydrous magnesium sulphate, and the solvent 
was evaporated from the dried liquid at a temperature of 40.degree. C. and 
a pressure of 24 mbar to give a residue (29.6 g) containing the desired 
product (yield between 51 and 78%). Only the cis isomer had been formed. 
The NMR spectrum of the desired product showed the following absorptions: 
______________________________________ 
.delta. = 3.38 ppm (singlet, C--O--CH.sub.3) -- 
.delta. = 1.18 ppm (singlet, 
H.sub.3 C--C--CH.sub.3) -- 
.delta. = 4.2 ppm (multiplet, H--C--O--CH.sub.3) -- 
.delta. = 1.1 ppm (multi- 
plet, --H--C--CH.sub.2) 
.delta. = 1.2 ppm (multiplet, H--C--C(H)-- -- 
.delta. = 4.2 ppm (multi- 
(OCH.sub.3).sub.2) plet, H--C--CH.sub.2) -- 
.delta. = 1.18 ppm (singlet, --H.sub.3 C--C--CH.sub.3) 
.delta. = 2.1 ppm (singlet, 
--H.sub.3 C--C(O)--O--) 
______________________________________ 
EMBODIMENT 6 
3-Hydroxymethyl-2,2-dimethylcyclopropanecarbaldehyde dimethyl acetal (the 
compound of formula III) 
A flask was charged with all of the residue obtained in Embodiment 5 above, 
water (75 ml), sodium hydroxide (150 mmol) and acetone (25 ml) and the 
liquid obtained was kept under reflux (60.degree. C.) for three hours. 
Then, the acetone and part of the water were evaporated at a pressure of 
16 mbar, the residue obtained was extracted with five 50 ml portions of 
diethyl ether (during the last two extractions sufficient sodium chloride 
was added so that the aqueous phase was saturated with this salt), the 
combined extracts were dried over anhydrous magnesium sulphate and the 
solvent was evaporated from the dried liquid at a temperature of 
40.degree. C. and a pressure of 24 mbar to give a residue containing the 
desired product in a yield of 51%, calculated on the product from 
Embodiment 5. The content of the desired product in the residue was 80%. 
The cis content of the desired product was 70%. The NMR spectrum of the 
cis isomer of the desired product showed the following absorptions: 
__________________________________________________________________________ 
.delta. = 3.32 ppm (singlet, C--O--CH.sub.3) -- 
.delta. = 1.05 ppm (singlet, H.sub.3 C--C--CH.sub.3) 
-- 
.delta. = 4.83 ppm (singlet, --H--C--O--CH.sub.3) 
.delta. = 1.2 ppm (multiplet, --H--C--CH.sub.2) 
.delta. = 1.53 ppm (doublet, --H--C--C(H)-- 
.delta. = 3.8 ppm (doublet, --H.sub.2 C--OH) 
(OCH.sub.3).sub.2) 
.delta. = 1.05 ppm (singlet, --H.sub.3 C--C--CH.sub.3) 
.delta. = 4.3 ppm (singlet, H.sub.2 COH) -- 
__________________________________________________________________________ 
EMBODIMENT 7 
3-Formyl-2,2-dimethylcyclopropanecarbaldehyde dimethyl acetal (the compound 
of formula IV) 
A flask was charged with a mixture of pyridine (120 mmol) and methylene 
chloride (150 ml) and then with chromium trioxide (60 mmol) at a 
temperature of 20.degree. C. The contents of the flask were stirred for 15 
minutes. Then, a solution of 1.74 g of the residue obtained in Embodiment 
6 above which contained 6.39 mmol of the desired product of Embodiment 
6--in methylene chloride (5 ml) was added to the contents of the flask and 
stirring was continued for 20 minutes. The precipitate in the flask was 
allowed to settle, the liquid in the flask was decanted, the precipitate 
was washed with three 25 ml portions of diethyl ether, the three washings 
were filtered over a bed of 2 cm Florisil (trademark), the combined three 
filtrates were washed with two 20 ml portions of a 5%w aqueous solution of 
sodium hydroxide and then with two 20 ml portions of water and the 
combined washed ethereal liquids were added to the decanted liquid. The 
liquid thus obtained was dried over anhydrous magnesium sulphate and the 
solvent was evaporated from the dried liquid at a pressure of 16 mbar to 
give a residue containing the desired product in a yield of 59%, 
calculated on starting material (product from Embodiment 6). The content 
of the desired product in the residue was 46.5%. The cis content of the 
desired product was 70%. The NMR spectrum of the cis isomer of the desired 
product showed the following absorptions: 
__________________________________________________________________________ 
.delta. = 3.30 ppm (singlet, C--O--C --H.sub.3) 
.delta. = 1.8 ppm (doublet, --H--C--C(O)H) 
.delta. = 4.8 ppm (doublet, --H--C--O--CH.sub.3) 
.delta. = 9.6 ppm (doublet, --H--C.dbd.O) 
.delta. = 1.2 ppm (multriplet, --H--C--C(H)--(OCH.sub.3).sub.2) 
.delta. = 1.22 ppm (singlet, --H.sub.3 C--C--CH.sub.3) 
.delta. = 1.37 ppm (singlet, H.sub.3 C--C--C --H.sub.3) 
__________________________________________________________________________