Specific dehydrogenation process (I)

Abstract

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

Claims

1. A process for the production of a compound of formula (II): ##STR00016## wherein R is CHO or CH.sub.2OCOR, wherein R is a C.sub.1-C.sub.16 alkyl group, wherein the process comprises conducting in the presence of at least one oxidative reactant and in the presence of at least one additive compound a selective dehydrogenation of a compound of formula (I): ##STR00017## wherein R has the same meanings as in the compound of formula (II), wherein the at least one oxidative reactant is a compound 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. The process according to claim 1, wherein the at least one oxidative reactant is selected from the group consisting of compounds of formulas (IIIa), (IIIb) and (IIIc): ##STR00019##

3. The process according to claim 1, wherein the at least one oxidative reactant is a compound of formula (IIIc): ##STR00020##

4. The process according to claim 1, wherein the at least one oxidative reactant of formula (III) is present in an amount of from 0.5 mol-equivalent up to 5 mol-equivalent in relation to the compound of formula (II).

5. The process according to claim 1, wherein the at least one additive compound is selected from the group consisting of pyridine, butylhydroxyltoluol, hydroquinone and triethoxyamine.

6. The process according to claim 1, wherein the at least one additive compound is present in an amount of 0.0011 mol-equivalent in relation to the compound of formula (II).

7. The process according to claim 1, wherein the process comprises conducting the selective dehydrogenation in the presence of at least one inert solvent.

8. The process according to claim 7, wherein the at least one inert solvent is an aromatic hydrocarbon solvent.

9. The process according to anyone of the preceding claims, wherein the process comprises conducting the selective dehydrogenation at a temperature of 0 C.120 C.

10. The process according to claim 1, wherein R is CH.sub.3, CH.sub.2CH.sub.3 or C.sub.15H.sub.31.

11. A compound of formula (Ia): ##STR00021##

12. A compound of formula (Ib): ##STR00022##

Description

EXAMPLES

Example 1

(1) 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

(2) 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

(3) 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

(4) 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

(5) 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).