GB1591968A – Process for the preparation of 8-oxoacetals
– Google Patents
GB1591968A – Process for the preparation of 8-oxoacetals
– Google Patents
Process for the preparation of 8-oxoacetals
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Publication number
GB1591968A
GB1591968A
GB1965578A
GB1965578A
GB1591968A
GB 1591968 A
GB1591968 A
GB 1591968A
GB 1965578 A
GB1965578 A
GB 1965578A
GB 1965578 A
GB1965578 A
GB 1965578A
GB 1591968 A
GB1591968 A
GB 1591968A
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methyl
process according
carbon atoms
hydrogen
alkyl
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1977-05-17
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GB1965578A
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Rhone Poulenc Industries SA
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Rhone Poulenc Industries SA
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1977-05-17
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1978-05-15
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1981-07-01
1978-05-15
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1981-07-01
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C—CHEMISTRY; METALLURGY
C07—ORGANIC CHEMISTRY
C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
C07C47/00—Compounds having —CHO groups
C07C47/20—Unsaturated compounds having —CHO groups bound to acyclic carbon atoms
C07C47/277—Unsaturated compounds having —CHO groups bound to acyclic carbon atoms containing ether groups, groups, groups, or groups
C—CHEMISTRY; METALLURGY
C07—ORGANIC CHEMISTRY
C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
C07C45/51—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition
C07C45/511—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition involving transformation of singly bound oxygen functional groups to >C = O groups
Abstract
An ortho ester of an alcohol is reacted, in the presence of a Lewis acid, with a 1,3-dieneoxysilane derived from an enolisable alpha , beta – or beta , gamma -ethylenic aldehyde or ketone. The ethylenic delta -oxoacetals can be used especially for preparing delta -dicarbonyl compounds and in particular delta -dialdehydes.
Description
(54) PROCESS FOR THE PREPARATION OF bOXOACETALS (71) We, RHONE-POULENC INDUSTRIES, a French Body Corporate, of 22 avenue Montaigne, 75008 Paris, France, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to the preparation of b-oxoacetals containing an ethylenic double bond in the A,y position relative to the acetal group, and to novel b-oxoacetals thus obtained.
It is known that ortho-esters and, in particular ortho-formates of lower afkanols can be condensed, in the presence of Lewis acids, with enol derivatives of aldehydes or of ketones, such as enol ethers and enoxysilanes. In the case of enol ethers, the reaction carried out in the presence of Lewis acids such as BF3, ZnCl2 and FeCI3 leads to the formation of bis-p-acetals which, after hydrolysis, provide a route to p-dicarbonyl compounds (compare L. S. Povarov, Russ. Chem. Rev., 34, pages 649-650 [1965]; Mezheritski et al., Russ. Chem. Rev., 42, pages 396-397 [1973]; and F. Effenberger, Angew. Chem. Internat. Ed., 8,pages295-312 [1969]).
The condensation of enoxysilanes with ortho-formates in the presence of large amounts of titanium tetrachloride gives rise to the formation of A-oxoacetals (compare T. Mukayama et al., Chem. Letters, 1974, pages 15-16; and ibid., 1976, pages 1,033-1,036). Povarov (loc. cit.) points out that alkoxydienes are incapable of reacting with ortho-esters to form condensation products, whereas they react easily with acetals (in particular acetals of a»B-ethylenic.aldebydes), in the presence of Lewis acids, to give a,-ethylenic X-alkoxyacetals (compare also S. M. Makin,
Russ. Chem. Rev., 38, pages 237-248 [1969]). Contrary to all expectations, it has been found that 1,3-dienoxysilanes react with ortho-esters.
The present invention more particularly provides a process for the preparation of A,y-ethylenic b-oxoacetals, which comprises reacting an ortho-formate ester of an (alkanol), in the presence of a Lewis acid, with a 1 ,3-dienoxysilane of the formula:
in which each of R1, R2, R3, R4 and R5, which are identical or different, is hydrogen or a hydrocarbon radical, R6 is a hydrocarbon radical, and n is an integer from 1 to 3. (In the following text, the term «dienoxysilane» means a 1,3-dienoxysilane df the aforesaid formula). The said ortho-formate ester is preferably an ester of an alkanol of the formula: H-C(OR)3 (Il) in which R is straight or branched alkyl of 1 to 4 carbon atoms.
The products of this new process are the p,y-ethylenic b-oxoacetals of the formula:
in which R is straight or branched alkyl, preferably of I to 4 carbon atoms, and
each of R1, R2, R3, R4 and R5, which are identical or different, is hydrogen or a
hydrocarbon radical.
In the formulae (I) to (III), the various symbols can more particularly
represent the following: R to R5, which are identical or different, may represent hydrocarbon radicals havihg from 1 to 20 carbon atoms each, such as straight or branched alkyl, straight
or branched alkenyl, cycloalkyl of 5 to 6 cyclic carbon atoms, or phenyl:
R may represent methyl ethyl, n-propyl, isopropyl or n-butyl; and
R6 may represent a straight or branched alkyl of from I to 4 carbon atoms, such as one of those mentioned above, cycloalkyl (e.g. cyclopentyl or cyclohexyl), phenyl, or arylalkyl (e.g. benzyl or p-phenylethyl). Although R6 can have the most varied meanings, it is preferable for practical reasons to employ dienoxysilanes of the formula (1), in which R6 represents methyl, ethyl or phenyl. When n is 2 or 3, the radicals Ra can be identical or different.
Rl to R5 can more particularly represent alkyl radicals such as methyl, ethyl, npropyl, isopropyl, n-butyl, sec.-butyl, pentyl, hexyl, octyl or dodecyl, alkenyl radicals containing one or more ethylenic double bonds, such as vinyl, propen-l-yl, allyl, buten-l-yl, buten-2-yl or isobutenyl provided preferably that R2 does not contain an ethylenic double bond conjugated with the enol double bond, and R4 and R5 do not contain a double bond conjugated with that of the carbon to which they are attached or cyclohexyl, cyclopentyl, phenyl, tolyl, or xylyl.
R is preferably methyl or ethyl.
R1 preferably is alkyl of 1 to 4 carbon atoms or, even more preferably, hydrogen;
R2, R3, R4 and Rs preferably represent hydrogen or alkyl of 1 to 4 carbon atoms especially methyl or ethyl. It is especially preferred for R1, R2 and R3 to be hydrogen, one of R4 and R5 to be hydrogen and the other hydrogen or methyl, Ra is preferably methyl or ethyl and n is preferably 3.
The dienoxysilanes of the formula (I), which are used in the process of the invention, are generally known products which can be easily prepared by reacting a mono-, di-, or tri-halogenosilane of the general formula: (R6)nS(X)4-N in which R6 and n are as defined above and X represents a halogen atom (chlorine or bromine), with an enolisable cu,p- or B,y-ethylenic aldehyde or ketone, in the presence of zinc chloride and a hydroacid acceptor in accordance with the process described in Belgian Patent 670,769
Suitable enoxysilanes of the formula (I) include the following:
A. Those derived from aldehydes. such as. (1,3 – butadienyloxy) trimethylsilane, (1,3 – butadienyloxy) – triethylsilane, bis – (1,3 – butadienyloxy) dimethylsilane, (3 – methyl – 1,3 – butadienyloxy) – trimethylsilane, (3 – ethyl
1,3 – butadienyloxy) – trimethylsilane, (2 – methyl – 1,3 – butadienyloxy) trimethylsilane, (4 – methyl – 1,3 – pentadienyloxy) – trimethylsilane, (1,3 hexadienyloxy)- trimethylsilane, (3 – methyl – 1,3 – pentadienyloxy) trimethylsilane, (2 – methyl – 1,3 – hexadienyloxy) – trimethylsilane and (3,4 dimethyl – 1,3 – pentadienyloxy) – trimethylsilane, and
B. Those derivedfrom ketones, such as: 4 – trimethylsilyloxy – 1,3 – pentadiene, 4 – trimethylsilyloxy – 1,3 – hexadiene, 2 methyl – 4 – trimethylsiloxy – 1,3 pentadiene, 3 – methyl – 4 – trimethylsilyloxy – 1,3 – pentadiene and 2 – methyl 4 – trimethylsilyloxy – 1,3 – hexadiene.
Suitable ortho-formates for the process of the invention, are preferably the methyl and ethyl ortho-formates which provide a route to ,y-ethylenic – oxoacetals which, by hydrolysis, lead to ,y-ethylenic b-ketoaldehydes and to ethylenic b-dialdehydes.
It is believed that the condensation of ortho-formates with dienoxysilanes in accordance with the invention can be represented by the following equation:
The alkoxysilane formed during the reaction is a by-product of industrial value; in fact, it can be used in the synthesis of polysiloxane polymers. It can also be converted into an organohalogenosilane by the customary processes, and the latter can be used again for the preparation of the starting enoxysilanes.
The amounts of dienoxysilane and ortho-formate which are employed to carry out the reaction can be near the stoichiometric amounts, that is to say about one mol of ortho-formate per dienoxy group present in the dienoxysilane, or they can deviate substantially from the stoichiometric amounts, it being possible to use an excess of one or other of the reactants, and preferably an excess of ortho-formate.
The amount of ortho-formate can more particularly be between I and 5 mols, and preferably between 1 and 2 mols, per dienoxy group present in the dienoxysilane.
The condensation of the ortho-formate with the dienoxysilane can be carried out either in an organic solvent which is inert towards the reactants used, or in the absence of any solvent. In the first case, the following can be employed as solvents: aliphatic hydrocarbons (e.g. hexane or heptane), cycloaliphatic hydrocarbons (e.g.
cyclohexane), aromatic hydrocarbons (e.g. benzene), ethers (e.g. ethyl ether or
tetrahydrofuran), halogenated hydrocarbons (e.g. methylene chloride, chloroform or carbon tetrachloride), nitriles (e.g. acetonitrile or propionitrile), or carboxamides (e.g. dimethylformamide, dimethylacetamide or N-methylpyrrolidone).
The temperature at which the reaction is carried out can vary within wide limits, depending upon the reactants employed and on the nature and amount of the catalyst. In general, the reaction is carried out at between -40 and +50″C, and preferably between 0 and +100″C. A temperature of between +10 and’+700C is very suitable. However, it is possible to carry out the reaction outside these limits.
The pressure can be equal to, less than or greater than atmospheric pressure: for example, it is possible to work in a closed vessel at the autogenous pressure of the reactants.
As Lewis acids which can be used as catalysts, there may be mentioned boron halides and their complexes with ethers, and transition metal halides (metals of groups lb to 7b and 8 of the periodic classification of the elements: Handbook of
Chemistry and Physics, 53rd edition, published by The Chemical Rubber Co.) Zinc halides and tin halides are particularly suitable and are preferably used. Thus, zinc chloride and bromide and stannous and stannic chlorides and bromides may be used.
The amount of catalyst, expressed as the number of mols of Lewis acid per dienoxy group present in the dienoxysilane, can vary within wide limits. In general, from lx 10-4 to 0.5 mol of Lewis acid, and particularly of zinc or tin halide, per dienoxy group is sufficient to carry out the reaction successfully. This amount is preferably between 1×10-3 mol and 0.2 mol per dienoxy group.
The duration of the reaction depends on the conditions chosen and on the nature of the reactants, and it can vary between a few minutes and several hours.
The present invention further provides, as new products, the ,y-ethylenic b- oxoacetals of the formula:
in which each of R2 to R5, which are identical or different, is hydrogen or alkyl of I to 4 carbon atoms, and R is as hereinbefore defined, provided that when R2 to R5 are identical and represent hydrogen, R is not methyl, and when R2 is methyl, and
R3 to R5 are identical and represent hydrogen, R is not ethyl. Especially valuable are the compounds of formula IV in which R is alkyl of I to 4 carbon atoms, R2 is methyl, and R2, R4 and R5 are each hydrogen.
5*5 – Dimethoxy – 3 – methylpenten – 2 – al, 5,5 – dimethoxy – 2 methylpenten – 2 – al, 5,5 – diethoxy – 3 – methylpenten – 2 – al and 5,5 dimethoxy – 3,4 – dimethylpenten – 2 – al may be mentioned as examples of ethylenic a – oxoacetals of the formula (IV).
These compounds are valuable intermediates in organic synthesis. They make it possible to obtain ethylenic dialdehydes which can be converted, by hydrogenation, into the corresponding pentane glycols which are used for the preparation of various polycondensates such as polyurethanes and polyesters (compare U.S. Patent 3,894,115). When reacted with alkyl ortho-formates in the presence of an acid catalyst (for example a sulphonic acid), they make it possible to obtain the corresponding bis-acetals which are difunctional compounds and very active in organic synthesis.
The following Examples illustrate the invention.
EXAMPLE 1
22.2 g of ethyl ortho-formate (1.5.10-‘mol), 0.37 g of molten zinc chloride (2.76.10-3 mol) and 50 cm3 of anhydrous acetonitrile are introduced, under an atmosphere of argon, into a 250 cm3 three-necked round-bottom flask which is equipped with a means of stirring, a condenser and a dropping funnel. The mixture is stirred, and a solution of 23.4 g of l-trimethylsiloxy-3-methyl-l,3-butadiene (1.5.10-‘ mol) in 15 cm3 of dry acetonitrile is run in over the course of 5 minutes.
The mixture is heated. Reflux is established at 76″C. After heating for 45 minutes, the mixture is cooled to 500C and distilled under pressure of 20 mm of mercy, while the uncondensed volatile products formed and the solvent are collected in a trap.
10.9 g of trimethylsiloxyethane, in the distillate and the trap, are determined and identified by vapour phase chromatography.
The residue is dissolved in 50 cm3 of diethyl ether and neutralised with 25 cm3 of a saturated aqueous solution of sodium bicarbonate. The ether phases are separated, washed with 25 cm3 of distilled water, and dried over potassium carbonate. After distilling off the solvents, 19 g of 5,5-diethoxy-3-methylpenten-2al, in a fraction which passes over at between 75 and 80″C under a pressure of 0.3 mm of mercury, are determined and identified by infra-red spectrometry, vapour phase chromatography and nuclear magnetic resonance.
After rectification, the 5,5 – diethoxy – 3 – methylpenten – 2 – al is in the form of a pale yellow liquid which boils at 730C under a pressure of 0.2 mm of mercury and has a refractive index nD20=1.4602.
The infra-red spectrum of this product, which principally consists of the transisomer and a small amount of the cis-isomer, exhibit the following characteristic bands:
at 1,6701,660 cm-‘ -C=C- at 1,630 cm-‘, and -C-O-C- at 1,100 and 1,050cm-‘ EXAMPLE 2
3.7 g of ethyl ortho-formate (2.5.10-2 mol), 3.9 g of I – trimethylsiloxy – 3 methyl – 1,3 – butadiene (2.5.10-2 mol) and 10 cm3 of methylene chloride are introduced, under a stream of argon, into a 50 cm3 three-necked round-bottomed flask which is equipped with a means of stirring, a condenser and a dropping funnel. 8 mg of stannic chloride (3.10-5 mol) are added rapidly using a syringe. The mixture is stirred and kept at 25″C for 5 minutes. The reaction mixture is neutralised with 25 cm3 of a saturated solution of sodium bicarbonate. 25 cm3 of diethvl ether are added, and the organic phase is then separated, washed with 25 cm3 of a saturated aqueous solution of sodium chloride, and dried over potassium carbonate.
After filtering off the potassium carbonate and removing the solvents under a pressure of 20 mm of mercury, the residue is distilled and a fraction of 2.1 g, which passes over at between 70 and 90″C under pressure of 0.3 mm of mercury, is obtained. In this fraction, 9lv of 5,5 – diethoxy – 3 – methylpenten – 2 – al is determined by vapour phase chromatography.
EXAMPLE 3
13.25 g of methyl ortho-formate (1.25.10-‘ mol), 0.312 g of zinc chloride (2.3.10-2 mol) and 40 cm3 of anhydrous acetonitrile are introduced, under an atmosphere of argon, into a 250 cm3 three-necked round-bottomed flask equipped with a means of stirring, a condenser and a dropping funnel. A solution of 19.5 g of
1 – trimethylsilyloxy – 3 – methyl – 1,3 – butadiene (1.25.10-‘ mol) in 15 cm3 of anhydrous acetonitrile is added to the mixture over the course of 5 minutes, while stirring.
The mixture is heated to reflux temperature; after 1 hour 10 minutes, thin layer chromatography is used to check that all the 1 – trimethylsilyloxy – 3 – methyl 1,3 – butadiene has disappeared. The reaction mixture is cooled, and the acetronitrile is driven off under reduced pressure (20 mm of mercury). The residue is neutralised by adding 50 cm3 of a saturated aqueous solution of sodium bicarbonate, and 25 cm3 of diethyl ether are then added. The ether phase is separated, dried over potassium carbonate and then concentrated. By distilling the residue, 12.7 g of 5,5 – dimethoxy – 3 – methylpenten – 2 – al, boiling point 70- 75″C/0.4 mm. Hg. are obtained. The compound is’ identified by gas-liquid chromatography and NMR.
WHAT WE CLAIM IS:
1. Process for the preparation of a P,v-ethylenic boxoacetal, which comprises reacting an ortho-formate ester of an alkanol, in the presence of a Lewis acid, with a 1,3-dienoxysilane of the formula:
in which R1, R2, R3, R4,and R,, which are identical or different, are each hydrogen or a hydrocarbon radical, R6 is a hydrocarbon radical, and n is an integer from I to 3.
2. Process according to claim 1, in which the said ortho-formate ester is an ester of the formula: H-C(OR)2 (tri) in which R is straight or branched alkyl of 1 to 4 carbon atoms.
3. Process according to claim 1 or 2, in which in the formula (I), each of R, to R5 represents a straight or branched alkyl of from I to 20 carbon atoms, a straight or branched alkenyl of 2 to 20 carbon atoms, R2 not containing any ethylenic double bond conjugated with the enolic double bond, and R4 and R5 not containing any ethylenic double bond conjugated with that of the carbon to which they are attached, cyclohexyl, cyclopentyl, or phenyl and R6 is alkyl of 1 to 4 carbon atoms, cycloalkyl phenyl or arylalkyl.
4. Process according to claim 1 or 2, in which in the formula (I), each of R1 to R5 represents hydrogen or alkyl of 1 to 4 carbon atoms, n is 3, and R6 is methyl, ethyl or phenyl radical.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (19)
**WARNING** start of CLMS field may overlap end of DESC **. funnel. 8 mg of stannic chloride (3.10-5 mol) are added rapidly using a syringe. The mixture is stirred and kept at 25″C for 5 minutes. The reaction mixture is neutralised with 25 cm3 of a saturated solution of sodium bicarbonate. 25 cm3 of diethvl ether are added, and the organic phase is then separated, washed with 25 cm3 of a saturated aqueous solution of sodium chloride, and dried over potassium carbonate. After filtering off the potassium carbonate and removing the solvents under a pressure of 20 mm of mercury, the residue is distilled and a fraction of 2.1 g, which passes over at between 70 and 90″C under pressure of 0.3 mm of mercury, is obtained. In this fraction, 9lv of 5,5 – diethoxy – 3 – methylpenten – 2 – al is determined by vapour phase chromatography. EXAMPLE 3 13.25 g of methyl ortho-formate (1.25.10-‘ mol), 0.312 g of zinc chloride (2.3.10-2 mol) and 40 cm3 of anhydrous acetonitrile are introduced, under an atmosphere of argon, into a 250 cm3 three-necked round-bottomed flask equipped with a means of stirring, a condenser and a dropping funnel. A solution of 19.5 g of 1 – trimethylsilyloxy – 3 – methyl – 1,3 – butadiene (1.25.10-‘ mol) in 15 cm3 of anhydrous acetonitrile is added to the mixture over the course of 5 minutes, while stirring. The mixture is heated to reflux temperature; after 1 hour 10 minutes, thin layer chromatography is used to check that all the 1 – trimethylsilyloxy – 3 – methyl 1,3 – butadiene has disappeared. The reaction mixture is cooled, and the acetronitrile is driven off under reduced pressure (20 mm of mercury). The residue is neutralised by adding 50 cm3 of a saturated aqueous solution of sodium bicarbonate, and 25 cm3 of diethyl ether are then added. The ether phase is separated, dried over potassium carbonate and then concentrated. By distilling the residue, 12.7 g of 5,5 – dimethoxy – 3 – methylpenten – 2 – al, boiling point 70- 75″C/0.4 mm. Hg. are obtained. The compound is’ identified by gas-liquid chromatography and NMR. WHAT WE CLAIM IS:
1. Process for the preparation of a P,v-ethylenic boxoacetal, which comprises reacting an ortho-formate ester of an alkanol, in the presence of a Lewis acid, with a 1,3-dienoxysilane of the formula:
in which R1, R2, R3, R4,and R,, which are identical or different, are each hydrogen or a hydrocarbon radical, R6 is a hydrocarbon radical, and n is an integer from I to 3.
2. Process according to claim 1, in which the said ortho-formate ester is an ester of the formula: H-C(OR)2 (tri) in which R is straight or branched alkyl of 1 to 4 carbon atoms.
3. Process according to claim 1 or 2, in which in the formula (I), each of R, to R5 represents a straight or branched alkyl of from I to 20 carbon atoms, a straight or branched alkenyl of 2 to 20 carbon atoms, R2 not containing any ethylenic double bond conjugated with the enolic double bond, and R4 and R5 not containing any ethylenic double bond conjugated with that of the carbon to which they are attached, cyclohexyl, cyclopentyl, or phenyl and R6 is alkyl of 1 to 4 carbon atoms, cycloalkyl phenyl or arylalkyl.
4. Process according to claim 1 or 2, in which in the formula (I), each of R1 to R5 represents hydrogen or alkyl of 1 to 4 carbon atoms, n is 3, and R6 is methyl, ethyl or phenyl radical.
5. Process according to claim 2, in which R is methyl or ethyl. R1, R2 and R3
are each hydrogen, one of R4 and R5 is hydrogen and the other is hydrogen or methyl, R6 is methyl or ethyl, and n is 3.
6. Process according to any one of claims I to 5, in which the Lewis acid used as the catalyst is a transition metal halide.
7. Process according to claim 6, in which the catalyst used is a zinc or tin halide.
8. Process according to any one of claims 1 to 7, in which the amount of catalyst, expressed in mols per dienoxy group present in the dienoxysilane, is between lx10-4 and 0.5.
9. Process according to any one of claims I to 8, in which the amount of orthoformate, expressed in mols per dienoxy group, is between I and 5.
10. Process according to any one of claims 1 to 9, in which the temperature of the reaction is between -40 and +150 C.
11. Process according to any one of claims I to 10, in which the reaction is carried out in the presence of an inert solvent.
12. Process according to claim 11, in which the solvent used is a chlorinecontaining saturated aliphatic hydrocarbon or a nitrile.
13. Process according to claim 1 for the preparation of a 5,5-dialkoxy-3methylpenten-2-al, which comprises reacting an alkyl ortho-formate in the presence of zinc chloride or tin chloride, with l-trimethylsilyloxy-3-methyl-l-,3- butadiene.
14. ,B,y-Ethylenic b-oxoacetals of the formula:
in which each of R2 to R5, which are identical or different, is hydrogen or alkyl of 1 to 4 carbon atoms, and R is alkyl of 1 to 4 carbon atoms provided that, when R2 to are identical and represent hydrogen R is not methyl, and when R2 is methyl, and
R3 to R5 are identical and represent hydrogen, R is not ethyl.
15. A 5,5-dialkoxy-3-methylpenten-2-al.
16. 5,5-Diethoxy-3-methylpenten-2-al.
17. 5,5-Dimethoxy-3-methylpenten-2-al.
18. Process according to claim I substantially as described in any one of
Examples 1 to 3.
19. A compound as claimed in any of claims 14 to 17 when prepared by a process claimed in any of claims 1 to 13 or 18.
GB1965578A
1977-05-17
1978-05-15
Process for the preparation of 8-oxoacetals
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GB1591968A
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PROCESS FOR PREPARING D-OXOACETALS
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FR2654105A1
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1989-11-09
1991-05-10
Univ Rouen
NOVEL DIENOXYSILANES, PROCESS FOR OBTAINING THEM, AND NOVEL ALPHA-HALOGENATED ALPHA-ETHYLENE ALDEHYDES TO WHICH THEY GIVE ACCESS.
1977
1977-05-17
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FR7715070A
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1978
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active
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1989-11-09
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NOVEL DIENOXYSILANES, PROCESS FOR OBTAINING THEM, AND NOVEL ALPHA-HALOGENATED ALPHA-ETHYLENE ALDEHYDES TO WHICH THEY GIVE ACCESS.
EP0428460A1
(en)
*
1989-11-09
1991-05-22
Universite De Rouen
Dienoxysilanes, methods for their preparation and alpha-ethylenic alpha-halo-aldehydes accessible therefrom
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JPS6159298B2
(en)
1986-12-16
HU179295B
(en)
1982-09-28
CH633246A5
(en)
1982-11-30
SU869553A3
(en)
1981-09-30
NL7804965A
(en)
1978-11-21
IT1096298B
(en)
1985-08-26
NL188634B
(en)
1992-03-16
FR2391181B1
(en)
1981-01-09
DE2821540C2
(en)
1988-02-18
JPS53141204A
(en)
1978-12-08
DD135481A5
(en)
1979-05-09
BE867127A
(en)
1978-11-16
NL188634C
(en)
1992-08-17
FR2391181A1
(en)
1978-12-15
IT7823510D0
(en)
1978-05-17
DE2821540A1
(en)
1978-11-23
CA1108646A
(en)
1981-09-08
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Description
1981-09-16
PS
Patent sealed
1996-01-10
PCNP
Patent ceased through non-payment of renewal fee
Effective date:
19950515
