The present invention relates to a method for producing a 3-methylcycloalkenone compound and a method for producing muscone. In the presence of a zirconium oxide catalyst, a diketone represented by the following general formula (1):

##STR00001##

wherein in formula (1), n represents 8, 9, 10, 11 or 12,
is subjected to a vapor-phase intramolecular condensation reaction, whereby a 3-methylcycloalkenone compound can be produced with high reaction efficiency. When a 3-methylcyclopentadecenone compound produced by this method is hydrogenated in a known manner, muscone can be produced efficiently.

The present invention relates to a method for producing a 3-methylcycloalkenone compound and a method for producing muscone. In the presence of a zirconium oxide catalyst, a diketone represented by the following general formula (1):

##STR00001##

wherein in formula (1), n represents 8, 9, 10, 11 or 12,
is subjected to a vapor-phase intramolecular condensation reaction, whereby a 3-methylcycloalkenone compound can be produced with high reaction efficiency. When a 3-methylcyclopentadecenone compound produced by this method is hydrogenated in a known manner, muscone can be produced efficiently.

Described is a process of making pseudoionone and hydroxy pseudoionone comprising the steps of (i) preparing a first aqueous mixture comprising first concentrations of acetone, citral and hydroxide, (ii) producing a second aqueous mixture by allowing to react for a reaction time the components of the first aqueous mixture and (iii) producing a third aqueous mixture by adding to the second aqueous mixture a second amount of hydroxide so that an additional amount of pseudoionone is formed in the third aqueous mixture. The invention further suggests an apparatus for making pseudoionone and hydroxy pseudoionone as well as to a respective process and use of said apparatus in making pseudoionone and hydroxy pseudoionone.

Described is a process of making pseudoionone and hydroxy pseudoionone comprising the steps of (i) preparing a first aqueous mixture comprising first concentrations of acetone, citral and hydroxide, (ii) producing a second aqueous mixture by allowing to react for a reaction time the components of the first aqueous mixture and (iii) producing a third aqueous mixture by adding to the second aqueous mixture a second amount of hydroxide so that an additional amount of pseudoionone is formed in the third aqueous mixture. The invention further suggests an apparatus for making pseudoionone and hydroxy pseudoionone as well as to a respective process and use of said apparatus in making pseudoionone and hydroxy pseudoionone.

Described is a process of making pseudoionone and hydroxy pseudoionone comprising the steps of (i) preparing a first aqueous mixture comprising first concentrations of acetone, citral and hydroxide, (ii) producing a second aqueous mixture by allowing to react for a reaction time the components of the first aqueous mixture and (iii) producing a third aqueous mixture by adding to the second aqueous mixture a second amount of hydroxide so that an additional amount of pseudoionone is formed in the third aqueous mixture. The invention further suggests an apparatus for making pseudoionone and hydroxy pseudoionone as well as to a respective process and use of said apparatus in making pseudoionone and hydroxy pseudoionone.

An efficient process useful for the self-condensation of aliphatic aldehydes is provided, catalyzed by dialkylammonium carboxylate salts. In particular, the invention provides a facile method for the preparation of 2-ethyl hexenal via the self-condensation of butyraldehyde using various dialkylammonium carboxylates, e.g., diisopropylammonium acetate or dimethylammonium acetate, as catalyst. Additionally, residual nitrogen arising from the catalyst can be reduced to −100 ppm levels in the product via a simple washing procedure. The invention provides a process for preparing alkenals under conditions which limit the formation of undesired impurities and high-boiling oligomeric substances.

An efficient process useful for the self-condensation of aliphatic aldehydes is provided, catalyzed by dialkylammonium carboxylate salts. In particular, the invention provides a facile method for the preparation of 2-ethyl hexenal via the self-condensation of butyraldehyde using various dialkylammonium carboxylates, e.g., diisopropylammonium acetate or dimethylammonium acetate, as catalyst. Additionally, residual nitrogen arising from the catalyst can be reduced to −100 ppm levels in the product via a simple washing procedure. The invention provides a process for preparing alkenals under conditions which limit the formation of undesired impurities and high-boiling oligomeric substances.

A (Z)-solanone has the steric formula of:

##STR00001##

with the name of (S,Z)-5-isopropyl-8-methyl-6,8-diene-2-one or (R,Z)-5-isopropyl-8-methyl-6,8-diene-2-one. A process for the preparation of the (Z)-type solanone and the use thereof in flavoring of cigarette shred are further disclosed. The process includes the following steps: (1) reacting isopentanal and methyl vinyl ketone, under the action of a catalyst and a co-catalyst, to give (S)-2-isopropyl-5-carbonylhexanal or (R)-2-isopropyl-5-carbonylhexanal; (2) reacting the (S)-2-isopropyl-5-carbonylhexanal or the (R)-2-isopropyl-5-carbonylhexanal obtained in step (1) with (iodomethyl)triphenylphosphonium iodide, to give (S,Z)-7-iodo-5-isopropyl-6-ene-2-one or (R,Z)-7-iodo-5-isopropyl-6-ene-2-one; and (3) reacting the (S,Z)-7-iodo-5-isopropyl-6-ene-2-one or the (R,Z)-7-iodo-5-isopropyl-6-ene-2-one obtained in step (2) with pinacol isopropenylborate in the presence of a catalyst to give the (Z)-solanone.

A (Z)-solanone has the steric formula of:

##STR00001##

with the name of (S,Z)-5-isopropyl-8-methyl-6,8-diene-2-one or (R,Z)-5-isopropyl-8-methyl-6,8-diene-2-one. A process for the preparation of the (Z)-type solanone and the use thereof in flavoring of cigarette shred are further disclosed. The process includes the following steps: (1) reacting isopentanal and methyl vinyl ketone, under the action of a catalyst and a co-catalyst, to give (S)-2-isopropyl-5-carbonylhexanal or (R)-2-isopropyl-5-carbonylhexanal; (2) reacting the (S)-2-isopropyl-5-carbonylhexanal or the (R)-2-isopropyl-5-carbonylhexanal obtained in step (1) with (iodomethyl)triphenylphosphonium iodide, to give (S,Z)-7-iodo-5-isopropyl-6-ene-2-one or (R,Z)-7-iodo-5-isopropyl-6-ene-2-one; and (3) reacting the (S,Z)-7-iodo-5-isopropyl-6-ene-2-one or the (R,Z)-7-iodo-5-isopropyl-6-ene-2-one obtained in step (2) with pinacol isopropenylborate in the presence of a catalyst to give the (Z)-solanone.

The present invention is directed to inhibitors of tyrosinase, pharmaceutical compositions comprising such tyrosinase inhibitors, and methods of making and using the same. Specifically, included in the present invention are compositions of matter comprised of at least one 2,4-dihydroxybenzene analog, which inhibit the activity of tyrosinase and which inhibit the overproduction of melanin.