SPECIFIC DEHYDROGENATION PROCESS (I)

Abstract

The present invention relates to a new dehydrogenation process of specific compounds.

Claims

1. Process for the production of the compounds of formula (II) ##STR00016## wherein R is —CH═O or —COOR′, wherein R′ is a —C.sub.1-C.sub.16 alkyl group (preferably —CH.sub.3 or —CH.sub.2CH.sub.3 or —C.sub.15H.sub.31), by selective dehydrogenation of the compounds of formula (I) ##STR00017## wherein R has the same meanings as in the compound of formula (II), wherein the dehydrogenation is carried out in the presence of at least one oxidative reactant of formula (III) ##STR00018## wherein R.sub.1 is —CN, —Cl or —F, R.sub.2 is —CN, —Cl or —F, R.sub.3 is —H, —CH.sub.3, —Cl or —F, and R.sub.4 is —H, —CH.sub.3, —Cl or —F.

2. Process according to claim 1, wherein the oxidative reactant is chosen from the group consisting of the compounds of formula (IIIa), (IIIb) and (IIIc) ##STR00019##

3. Process according to claim 1, wherein the oxidative reactant is the compound of formula (IIIc) ##STR00020##

4. Process according to claim 1, wherein the amount of the oxidative reactant of formula (III) goes from 0.5 mol-equivalent up to 5 mol-equivalent (in relation to compound of formula (II)).

5. Process according to claim 1, wherein the process is carried out in the presence of at least one additive compound.

6. Process according to claim 5, wherein the additive compound is chosen from the group consisting of pyridine, butylhydroxyltoluol, hydroquinone and triethoxyamine.

7. Process according to claim 5, wherein the additive compound is added in amount of 0.001-1 mol-equivalent (in relation to compound of formula (II)).

8. Process according to claim 1, wherein the process is carried out in the presence of at least one inert solvent. (Currently Amended) Process according to claim 8, wherein the solvent is an aromatic solvent.

10. Process according to anyone of the preceding claims, wherein the process is carried out at a temperature of from 0° C.-120° C.

11. Compound of formula (Ia) ##STR00021##

12. Compound of formula (Ib) ##STR00022##

13. Compound of formula (Ic) ##STR00023##

Description

EXAMPLES

Example 1

[0044] 7,8-Dihydroretinylactate (150 mg, 1.0 eq) were dissolved in toluene (5 mL) and DDQ (1.0 eq) and triethoxyamine (0.5 mol %) were added. The reaction mixture was stirred for 0.5 h at 90° C. The solution was filtered over a plug of silica and all volatiles were evaporated under reduced pressure. Purification by column chromatography afforded the desired product (54% yield).

Example 2

[0045] 7,8-Dihydroretinylactate (150 mg, 1.0 eq) were dissolved in toluene (5 mL) and DDQ (1.0 eq) was added. The reaction mixture was stirred for 4 h at 90° C. The solution was filtered over a plug of silica and all volatiles were evaporated under reduced pressure. Purification by column chromatography afforded the desired product (30% yield).

Example 3

[0046] 7,8-Dihydroretinal (150 mg, 1.0 eq) were dissolved in toluene (5 mL) and fluoranil (2.0 eq) was added. The reaction mixture was stirred 24 h at 60° C. The solution was filtered over a plug of silica and all volatiles were evaporated under reduced pressure. Purification by column chromatography afforded the desired product (29% yield).

Example 4

[0047] 7,8-Dihydroretinyl acetate (180 mg, 1.0 eq) were dissolved in ethylacetate (20 mL) and DDQ (1.0 eq) and triethoxyamine (0.5 mol %) were added. The reaction mixture was stirred for 0.5 h at 77° C. The solution was filtered over a plug of silica and all volatiles were evaporated under reduced pressure. Purification by column chromatography afforded the desired product (74% yield).

Example 5

[0048] 7,8-Dihydroretinyl acetate (181 mg, 1.0 eq) were dissolved in ethylacetate (5 mL) and DDQ (1.0 eq) and triethoxyamine (0.5 mol %) were added. The reaction mixture was stirred for 0.5 h at room temperature and 0.5 h at 77° C. The solution was filtered over a plug of silica and all volatiles were evaporated under reduced pressure. Purification by column chromatography afforded the desired product (75% yield).