The present invention is related to a method for increasing the trans-specificity of a beta-carotene oxidase (BCO), particularly insect BCO, to be used in the production of vitamin A aldehyde (retinal) from conversion of beta-carotene, with at least about 75 to 100% of retinal in the trans-isoform.

The present invention relates to a new process for the production of vitamin A and/or its derivatives.

The invention relates to an improved process for isomerizing polyunsaturated non-aromatic compounds including acyclic conjugated polyenes and alicyclic conjugated polyenes. In particular it relates to an improved and safe process for forming a 11-E retinoid compounds in high yield by expending as few energy as possible and with avoiding at most possible side products or product mixtures. This is achieved by feeding at least one of retinoid compounds of formula 2 to 5, or at least one of retinoid compounds of formula 2 to 5 and retinoid compound of formula 1, an organic solvent and a photosensitizer into a reaction device and irradiating the thus obtained reaction mixture with visible monochromatic light, at least 90% of the power of said monochromatic light and at most 100% of said power being emitted in the range from 460 nm to 580 nm.

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

The present invention relates to new specific enol esters of formula (I) as well as to a process for their production. In formula (I) R is COR′ where R′ is a C.sub.1-C.sub.16 alkyl group.

##STR00001##

The present invention relates to new specific enol esters of formula (I) as well as to a process for their production. In formula (I) R is COR′ where R′ is a C.sub.1-C.sub.16 alkyl group.

##STR00001##

A method for preparing a compound of formula (I) ##STR00001## in which R1 is selected from H and alkyls, R2 is selected from H, alkyls, OR′ where R′ is selected from alkyls, silyls, CO-alkyl, R3 is selected from the acyl groups of the CO(R″) type, and the CO(OR″), CO(NR″R′″), PO(OR″)(OR′″), PO(OR″)(R′″) groups where R″ and R′″, independently of each other, are selected from H and alkyls, R represents a C(R4)═C(R5)(R6) group where R4, R5 and R6, independently of each other, are selected from H, linear or cyclic alkyls and alkenyls, aryls, alkylaryls, or R4 and R5 together form a saturated or unsaturated, substituted or unsubstituted ring, from a compound of formula (II) ##STR00002## or a compound of formula (III) ##STR00003## in which, R, R1, R2 and R3 have the above definition.

Processes for synthesizing new compounds that may usefully be employed in organic synthesis, especially in the synthesis of vitamin A or β-carotene and derivatives thereof, e.g. canthaxanthin, astaxanthin or zeaxanthin are disclosed. The new compounds are especially useful as intermediates (building blocks) in the synthesis of vitamin A or β-carotene, preferably vitamin A.

The present invention relates to a process for producing specific α,β-unsaturated carboxylates.

The present invention relates to new specific enol esters of formula (I) as well as to a process for their production by acylation of the corresponding dihydroretinal analogue. In formula (I) R is —COR′ where R′ is a C.sub.1-C.sub.16 alkyl group.

##STR00001##