The invention discloses a process for the oxidation of limonene, comprising the reaction of limonene with hydrogen peroxide in the presence of a catalyst containing atoms and/or ions of at least one metal, selected from the group consisting of molybdenum, tungsten, scandium, vanadium, titanium, lanthanum, zirconium, praseodymium, neodymium, samarium, europium, terbium, dysprosium, erbium or ytterbium, characterised in that the molecular weight of the catalyst is less than 2,000 g/mol and that the reaction is performed at a pH value of more than 7.5.

The invention discloses a process for the oxidation of limonene, comprising the reaction of limonene with hydrogen peroxide in the presence of a catalyst containing atoms and/or ions of at least one metal, selected from the group consisting of molybdenum, tungsten, scandium, vanadium, titanium, lanthanum, zirconium, praseodymium, neodymium, samarium, europium, terbium, dysprosium, erbium or ytterbium, characterised in that the molecular weight of the catalyst is less than 2,000 g/mol and that the reaction is performed at a pH value of more than 7.5.

The present invention relates to a particularly economic overall method for producing menthol, specifically for producing optically active, essentially enantiomerically and diastereomerically pure L-menthol and racemic menthol, starting from the starting material citral which is available inexpensively on an industrial scale. The method has the following steps a.1) catalytic hydrogenation of neral and/or geranial to give citronellal, b.1) cyclization of citronellal to isopulegol in the presence of an acidic catalyst, c.1) purification of isopulegol by crystallization and d.1) catalytic hydrogenation of isopulegol to give menthol.

The present invention relates to a particularly economic overall method for producing menthol, specifically for producing optically active, essentially enantiomerically and diastereomerically pure L-menthol and racemic menthol, starting from the starting material citral which is available inexpensively on an industrial scale. The method has the following steps a.1) catalytic hydrogenation of neral and/or geranial to give citronellal, b.1) cyclization of citronellal to isopulegol in the presence of an acidic catalyst, c.1) purification of isopulegol by crystallization and d.1) catalytic hydrogenation of isopulegol to give menthol.

The present invention relates to a process for the preparation of an optically active carbonyl compound by asymmetric hydrogenation of a prochiral ,-unsaturated carbonyl compound with hydrogen in the presence of at least one optically active transition metal catalyst that is soluble in the reaction mixture and which has rhodium as catalytically active transition metal and a chiral, bidentate bisphosphine ligand, wherein the reaction mixture during the hydrogenation of the prochiral ,-unsaturated carbonyl compound additionally comprises at least one compound of the general formula (I): ##STR00001##
in which R.sup.1, R.sup.2: are identical or different and are C.sub.6- to C.sub.10-aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C.sub.1- to C.sub.6-alkyl, C.sub.3- to C.sub.6-cycloalkyl, C.sub.6- to C.sub.10-aryl, C.sub.1- to C.sub.6-alkoxy and amino; Z is a group CHR.sup.3R.sup.4 or aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C.sub.1- to C.sub.6-alkyl, C.sub.3- to C.sub.6-cycloalkyl, C.sub.6- to C.sub.10-aryl, C.sub.1- to C.sub.6-alkoxy and amino, wherein R.sup.3 and R.sup.4 are as defined in the claims and the description.

The present invention relates to a process for the preparation of an optically active carbonyl compound by asymmetric hydrogenation of a prochiral ,-unsaturated carbonyl compound with hydrogen in the presence of at least one optically active transition metal catalyst that is soluble in the reaction mixture and which has rhodium as catalytically active transition metal and a chiral, bidentate bisphosphine ligand, wherein the reaction mixture during the hydrogenation of the prochiral ,-unsaturated carbonyl compound additionally comprises at least one compound of the general formula (I): ##STR00001##
in which R.sup.1, R.sup.2: are identical or different and are C.sub.6- to C.sub.10-aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C.sub.1- to C.sub.6-alkyl, C.sub.3- to C.sub.6-cycloalkyl, C.sub.6- to C.sub.10-aryl, C.sub.1- to C.sub.6-alkoxy and amino; Z is a group CHR.sup.3R.sup.4 or aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C.sub.1- to C.sub.6-alkyl, C.sub.3- to C.sub.6-cycloalkyl, C.sub.6- to C.sub.10-aryl, C.sub.1- to C.sub.6-alkoxy and amino, wherein R.sup.3 and R.sup.4 are as defined in the claims and the description.

The present invention relates to a process for the preparation of an optically active carbonyl compound by asymmetric hydrogenation of a prochiral ,-unsaturated carbonyl compound with hydrogen in the presence of at least one optically active transition metal catalyst that is soluble in the reaction mixture and which has rhodium as catalytically active transition metal and a chiral, bidentate bisphosphine ligand, wherein the reaction mixture during the hydrogenation of the prochiral ,-unsaturated carbonyl compound additionally comprises at least one compound of the general formula (I):

##STR00001##

in which R.sup.1, R.sup.2: are identical or different and are C.sub.6- to C.sub.10-aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C.sub.1- to C.sub.6-alkyl, C.sub.3- to C.sub.6-cycloalkyl, C.sub.6- to C.sub.10-aryl, C.sub.1- to C.sub.6-alkoxy and amino; Z is a group CHR.sup.3R.sup.4 or aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C.sub.1- to C.sub.6-alkyl, C.sub.3- to C.sub.6-cycloalkyl, C.sub.6- to C.sub.10-aryl, C.sub.1- to C.sub.6-alkoxy and amino, wherein R.sup.3 and R.sup.4 are as defined in the claims and the description.

The present invention relates to a process for the preparation of an optically active carbonyl compound by asymmetric hydrogenation of a prochiral ,-unsaturated carbonyl compound with hydrogen in the presence of at least one optically active transition metal catalyst that is soluble in the reaction mixture and which has rhodium as catalytically active transition metal and a chiral, bidentate bisphosphine ligand, wherein the reaction mixture during the hydrogenation of the prochiral ,-unsaturated carbonyl compound additionally comprises at least one compound of the general formula (I):

##STR00001##

in which R.sup.1, R.sup.2: are identical or different and are C.sub.6- to C.sub.10-aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C.sub.1- to C.sub.6-alkyl, C.sub.3- to C.sub.6-cycloalkyl, C.sub.6- to C.sub.10-aryl, C.sub.1- to C.sub.6-alkoxy and amino; Z is a group CHR.sup.3R.sup.4 or aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C.sub.1- to C.sub.6-alkyl, C.sub.3- to C.sub.6-cycloalkyl, C.sub.6- to C.sub.10-aryl, C.sub.1- to C.sub.6-alkoxy and amino, wherein R.sup.3 and R.sup.4 are as defined in the claims and the description.

Disclosed is a method for production of oxygenated diterpenoid compounds, such as triptophenolide, triptonide and triptolide, by inserting genes encoding particular cytochrome P450 enzymes and expressing the genes in selected host cells for synthesis of the compounds. Further disclosed are particular cytochrome P450 enzymes suitable for this synthesis.

Disclosed is a method for production of oxygenated diterpenoid compounds, such as triptophenolide, triptonide and triptolide, by inserting genes encoding particular cytochrome P450 enzymes and expressing the genes in selected host cells for synthesis of the compounds. Further disclosed are particular cytochrome P450 enzymes suitable for this synthesis.