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US 5,471,005 AGranted
Method of making 2,7-dimethyl-2,4,6-octatrienedial, a key intermediate in the commercial syntheses of various carotenoids
AssigneeLoyola University of Chicago
InventorJames H. Babler
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Abstract
A procedure for forming methylmalonaldehyde from propionaldehyde, an alkyl formate and a sodium alkoxide, utilizing a crossed-Claisen condensation is disclosed. The procedure avoids the formation of aldol condensation products. Also disclosed are processes for preparing 3-alkoxy-2-methylpropenals such as 2-methyl-3-(2-methyl-2-propenoxy)propenal from methylmalonaldehyde. The latter products are useful in the synthesis of carotenoids.
Claims21
A process for forming sodium methylmalonaldehyde comprising:
- A) forming a first reaction mixture comprising:
- i) one equivalent of a sodium alkoxide having the formula NaOR';
- ii) an alkyl formate of the formula HCOOR, wherein the molar quantity of said formate is in excess of the molar quantity of said alkoxide;
- and
- iii) an alcohol cosolvent of the formula R'OH;
- wherein R and R', which can be the same or different, are C.sub.1 -C.sub.4 alkyl;
- B) slowly adding propionaldehyde to said first reaction mixture at a rate whereby the molar ratio of alkyl formate to propionaldehyde is greater than 5000:1, while maintaining said reaction mixture at a temperature of between about 15.degree. C. and about 50.degree. C.
4 more elements
A process for forming 3-alkoxy-2-methylpropenals comprising:
- A) forming a first reaction mixture comprising:
- i) one equivalent of a sodium alkoxide having the formula NaOR';
- ii) an alkyl formate of the formula HCOOR, wherein the molar quantity of said formate is in excess of the molar quantity of said alkoxide;
- and
- iii) an alcohol cosolvent of the formula R'OH;
- wherein R and R', which can be the same or different, are C.sub.1 -C.sub.4 alkyl;
- B) slowly adding propionaldehyde to said first reaction mixture at a rate whereby the molar ratio of alkyl formate to propionaldehyde is greater than 5000:1, while maintaining said reaction mixture at a temperature of between about 15.degree. C. and about 50.degree. C., thereby forming sodium methylmalonaldehyde;
- C) forming a second reaction mixture in an organic solvent comprising:
- i) the sodium methylmalonaldehyde of step (B);
- and
- ii) a reactant selected from the group consisting of one or more of the following:
- a) a halide of the formula R''--X, wherein X is chloride or bromide, and R'' is C.sub.1 -C.sub.10 alkyl, C.sub.3 -C.sub.10 allylic or benzyl;
- and
- b) a sulfate ester of the formula:
- ##STR12## wherein R''' is C.sub.1 -C.sub.4 alkyl;
- and D) maintaining said second reaction mixture at a temperature in the range of about 15.degree. C. to about 100.degree. C.
13 more elements
A process for forming 3-alkoxy-2-methylpropenals comprising:
- A) forming a first reaction mixture comprising:
- i) one equivalent of a sodium alkoxide having the formula NaOR';
- ii) an alkyl formate of the formula HCOOR, wherein the molar quantity of said formate is in excess of the molar quantity of said alkoxide;
- and
- iii) an alcohol cosolvent of the formula R'OH;
- wherein R and R', which can be the same or different, are C.sub.1 -C.sub.4 alkyl;
- B) slowly adding propionaldehyde to said first reaction mixture at a rate whereby the molar ratio of alkyl formate to propionaldehyde is greater than 5000:1, while maintaining said reaction mixture at a temperature of between about 15.degree. C. and about 50.degree. C., thereby forming sodium methylmalonaldehyde;
- C) forming a second reaction mixture in an organic solvent comprising:
- i) the sodium methylmalonaldehyde of step (B);
- and
- ii) C.sub.1 -C.sub.4 primary or secondary alcohol and at least one equivalent of an acid having a pK.sub.a of less than 5;
- and
- D) heating said reaction mixture with continuous removal of water.
10 more elements
Dependencies are inferred from the claim text.