Takasago International Corporation

Sony Corporation

Toshiyuki Murayama

Takashi Miura

Takaji Matsumoto

Hideki Nara

Toyohiko Kobayashi

Takashi Moroi

Hidenori Kumobayashi

Noboru Sayo

Tetsuro Yamasaki

Kazuhiko Matsumura

Kenji Yagi

Tohru Yokozawa

Wataru Kuriyama

Tsukasa Sotoguchi

Noboru Sano

Akifumi Yoshida

Takero Ishizaki

Motonobu Takenaka

Takao Saito

Shigeru Mitsuhashi

Yoshiharu Gonda

Kenzo Sumi

Hiroshi Iino

An optical disc recording method of determining a disc address when write and read operations are performed for an optical disc during recording power calibration in an optical disc recording apparatus having at least two optical head units including first and second optical head units is disclosed. The method includes: determining a first recording power calibration start address, which is an address at which the first optical head unit starts calibration of the recording power, from a power calibration area provided in advance as an area used to calibrate the recording power; and determining an address obtained by adding a range of the power calibration area used to calibrate the recording power to the first recording power calibration start address as a second recording power calibration start address, which is an address at which the second optical head unit starts calibration of the recording power.

Optical disc recording method and optical disc recording apparatus

A reproduction apparatus includes a reproduction unit reading a reproduced signal of the data recorded on an optical disk, a reproduced signal processing unit performing ECC decoding for the reproduced signal using a predetermined parameter value, a storage unit storing the parameter number associated with the currently set parameter value and a parameter table listing parameter values and associated parameter numbers, and a control unit controlling the reproduction unit and the reproduced signal processing unit. The control unit, when ECC decoding fails, changes the parameter values in the order of the parameter numbers and controls the reproduced signal processing unit until ECC decoding succeeds in retried reproduction processing and, when ECC decoding succeeds, stores the parameter number associated with the currently set parameter value and sets in the next retried reproduction processing the parameter value associated with the stored parameter number in the reproduced signal processing unit.

Reproduction apparatus and reproduction method

Disclosed is an industrially advantageous production method of optically active &#x3b2;-amino acid of formula (5), which includes subjecting an enaminoester of formula (4) to an asymmetric hydrogenation: 

Method for producing an optically active tetrahydroquinoline

The present invention provides an industrially advantageous production method of optically active tetrahydroquinolines of formula (1), which comprises:      

A reproducing apparatus comprises detecting meansandfor detecting levels of pilot signals recorded on tracks from reproduced signals reproduced by magnetic headsA,B, a calculating meansfor calculating a ratio between levels detected by the detecting meansandwith respect to the pilot signals recorded on two tracks at both sides of the track traced by the magnetic headsA,B and a judging meansfor judging an off-track amount of the magnetic head from the value of the ratio calculated by the calculating means, wherein tracking can be effected on the magnetic headsA,B in response to the off-track amount judged by the judging means. In a reproducing apparatus like a VCR (video cassette recorder) in which a magnetic head traces tracks on a tape-like recording medium, tracking can be effected on the magnetic head quickly in a short period of time.

Reproducing apparatus and tracking method

Ammonium 3,5,6-trihydroxyhexanoate derivatives and preparation process thereof

Process for the preparation of 4-substituted azetidinone derivatives

A process for producing cyclohexylazetidinone expressed by the formula(IV) comprises condensing the magnesium enolate compound expressed by the formula (II) with acyloxyazetidinone expressed by the formula (III), wherein Me is a methyl group; R.sup.1 is a hydroxyl-protecting group, R.sup.2 is an acyl group, and X is a halogen atom. ##STR1##

Process for producing cyclohexylazetidinone

A process for producing an optically active cyclohexanol derivative represented by formula (I): ##STR1## wherein R.sup.1 represents an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, or a protected hydroxyl group, comprising asymmetrically hydrogenating a cyclohexanone derivative in the presence of a catalyst system composed of a transition metal compound (e.g., transition metal complex), a base (e.g., KOH), and a nitrogen compound (e.g., an amine compound).

Process for preparing optically active cyclohexanol derivatives

To prepare the compound (1'R,3S)-3-(1'-tri-substituted silyloxyethyl)azetidin-2-one, (2S,3R)-2-aminomethyl-3-hydroxybutyric acid is reacted with an alcohol in the presence of at least one compound chosen from the group consisting of thionyl chloride, hydrogen chloride and p-toluene sulfonic acid, thereby obtaining a salt of the corresponding ester. The salt is reacted with a tri-substituted silane in the presence of a metallic catalyst, thereby protecting the hydroxy group of the ester and then reacted with a base, thereby obtaining an ester of (2S,3R)-2-aminomethyl-3-(tri-substituted silyloxy)butyric acid. Subsequently, the ester is transformed into lactam in the presence of a Grignard reagent or a metal amide, thereby obtaining (1'R,3S)-3-(1'-tri-substituted silyloxyethyl)azetidin-2-one. This compound provides a useful base for preparing .beta.-lactam type antimicrobial agents such as carbapenem type agents.

Method of preparing a derivative of optically active azetidin-2-one

Disclosed herein is a process for producing a (2S,5S)-2,5-diamino-1,6-diphenyl-3-hexanone derivative represented by the formula (1): ##STR1## wherein R.sup.1 means a lower alkylcarbonyl group, a halogen-substituted lower alkylcarbonyl group, an arylcarbonyl group or a lower alkoxycarbonyl group, and R.sup.2 and R.sup.3 are identical with or different from each other and denote individually an aryl group or an alkoxy-substituted aryl group, which comprises subjecting a (2S)-2,5-diamino-1,6-diphenyl-4-hexen-3-one derivative represented by the formula (2): ##STR2## wherein R.sup.1, R.sup.2 and R.sup.3 have the same meaning as defined above, to a hydrogenation reaction in the presence of a transition metal-containing catalyst.

Process for producing optically active diaminohexanone derivative

A process for preferentially producing a 4-(1-carboxyalkyl) azetidin-2-one derivative represented by formula (II.beta.): ##STR1## wherein R.sup.3 represents a lower alkyl group and R.sup.4 represents a hydrogen atom or a hydroxy-protective group, which involves deesterifying and decarboxylating a 4-(1,1-dialkoxycarbonylalkyl) azetidin-2-one derivative represented by formula (I): ##STR2## wherein R.sup.1 and R.sup.2 are identical or different and each represents an alkyl group, an alkenyl group, or an aralkyl group, R.sup.3 and R.sup.4 each has the meaning as defined above, and R.sup.5 represents an amino-protective group, and after that, eliminating the amino-protective group from the derivative, where the 4-(1-carboxyalkyl)azetidin-2-one derivative of formula (II.beta.) is present in an amount of at least 61% by mol of all 4-(1-carboxyalkyl)azetidin-2-one derivatives produced.

4-(1,1-dialkoxycarbonylalkyl) azetidin-2-one derivative and process for

A 4-(1,1-dialkoxycarbonylalkyl )azetidin-2-one derivative represented by formula (I): ##STR1## wherein R.sup.1 and R.sup.2 are identical or different and each represents an alkyl group, an alkenyl group, or an aralkyl group, R.sup.3 represents a lower alkyl group, R.sup.4 represents a hydrogen atom or a hydroxyl-protective group, and R.sup.5 represents a hydrogen atom or an amino-protective group, and a process for producing a 4-(1-carboxyalkyl)azetidin-2-one derivative represented by formula (II) useful as an intermediate for 1.beta.-alkylcarbapenem-type antibacterials: ##STR2## wherein R.sup.3 represents a lower alkyl group and R.sup.4 represents a hydrogen atom or a hydroxyl-protective group, which comprises de-esterifying and decarboxylating the derivative represented by formula (I), and in the case where an amino-protective group is present in the derivative of formula (I), eliminating the protective group from the derivative, are disclosed.

4-(1,1-dialkoxycarbonylalkyl)azetidin-2-one derivative and process for

A process for preparing (1'R,3S)-3-(1'-hydroxyethyl)-azetidin-2-one or a derivative thereof represented by formula (I): ##STR1## wherein R.sup.1 represents a hydrogen atom or a hydroxyl-protective group, is disclosed, comprising reacting (2S,3R)-2-aminomethyl-3-hydroxybutyric acid or a derivative thereof represented by formula (II): ##STR2## wherein R.sup.1 is as defined above, with a sulfenamide represented by formula (III): ##STR3## wherein R.sup.2 represents ##STR4## and R.sup.3 and R.sup.4 each represent a hydrogen atom or a cyclic or acyclic hydrocarbon group, provided that they do not simultaneously represent a hydrogen atom, or R.sup.3 and R.sup.4 are taken together with the adjacent nitrogen atom to form a heterocyclic group, and triphenylphosphine. The reaction yield is high, and the sulfenamide (III) used as a lactamization reagent is cheap and can be recovered after the reaction.

Growing community of inventors

Kanagawa, Japan

Toshiyuki Murayama