METHOD FOR PRODUCING SPECIFIC ALPHA,BETA-UNSATURATED ALDEHYDES BY REARRANGEMENT PROCESS

Abstract

The present invention relates to an improved method for producing specific α,β-unsaturated aldehydes.

Claims

1. A process of production of a compound of formula (I) wherein ##STR00012## R.sup.1 is a C.sub.1-C.sub.4-alkyl moiety, preferably —CH.sub.3 or —CH.sub.2CH.sub.3, ##STR00013## R.sup.2 is by rearrangement of the compound of formula (II) ##STR00014## wherein R.sup.1 and R.sup.2 have the same meanings as in formula (I), wherein the process is carried out in the present of at least one transition metal based catalyst, wherein the transition metal is Cu and/or Ti.

2. A process according to claim 1, wherein the compound of formula (II) is the compound of formula (IIa) ##STR00015##

3. A process according to claim 1, wherein the compound of formula (II) is the compound of formula (IIb) ##STR00016##

4. A process according to claim 1, wherein the transition metal-based catalyst is a Cu/Ti-based catalyst.

5. A process according to claim 1, wherein the catalyst is CuCl/Ti(O)(acac).sub.2.

6. A process according to claim 1, wherein the substrate to catalyst ratio (mol-based) is from 5000:1 to 10:1, preferably from 1000:1 to 20:1.

7. A process according to claim 1, wherein the process is carried out in at least one non polar or polar aprotic organic solvent.

8. A process according to claim 1, wherein the process is carried out at a reaction temperature 50° C. to 120° C., preferably 60° C. to 100° C.

Description

EXAMPLES

Example 1

3-Methyl-5-(2,6,6-trimethylcyclohex-1-enyl)penta-2,4-dienal (compound of formula (Ib))

[0051] 8.74 mg of titanium(IV)-oxyacetylacetonate (0.03 mmol) and 4.08 mg of copper(I)-chloride (0.04 mmol) were added to a vial. The vial was sealed with a septum. 0.46 g of starting material (IIb, 2.00mmol) in 4 ml of anhydrous toluene was added. The solution was stirred for 15 hours at 90° C., then cooled to 23° C. and stirred for another 3.5 hours. The solution was diluted with 15 ml of ethyl acetate and washed with 15 ml of diluted brine (20%). The layers were separated and the organic layer was washed with another 15 ml of diluted brine (20%). The aqueous layers were re-extracted with 15 ml of ethyl acetate. The combined organic layers were dried over sodium sulfate, filtered and concentrated under reduced pressure at 30° C. water-bath temperature. The product (Ib) was obtained as a dark brown oil in 26.12% purity and 27% yield (0.455 g).

Example 2

Retinal (Compound of Formula (Ia))

[0052] 8.7 mg of titanium(IV)-oxyacetonylacetonate and 4.1 mg of copper(I)-chloride were added to a flask. A solution of 651.7 mg of starting material (IIa) in 4.0 ml of anhydrous toluene were added drop wise. The reaction mixture was heated to 85° C. in an oil bath under argon atmosphere. After 48 hours at 85° C. the dark brown suspension was cooled to 24° C. 15 ml of methylene chloride were added to the reaction mixture. The mixture was washed with 15 ml of semi-saturated NaHCO.sub.3-solution and 15 ml of semi-saturated brine. The layers were separated and the aqueous layers were re-extracted with 15 ml of methylene chloride. The combined organic layers were dried over sodium sulfate, filtered and concentrated under reduced pressure at 30° C. water bath temperature. The product (Ia) was obtained as dark orange oil (707.1 mg).