# US 7,608,709 B2 · 2, 3-bis(dialkylphosphino)pyrazine derivative, process of producing the same, and metal complex having the same as ligand

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- Number: US 7,608,709 B2
- Document ID: US7608709B2
- Status: Granted
- Kind: B2
- Application number: 11/359,369
- Filed: 2006-02-23
- Published: 2007-01-25
- Granted: 2009-10-27
- Earliest claimed: 2005-07-25
- Assignees: National University Corporation Chiba University; Nippon Chemical Industrial Co., Ltd.
- Inventors: Tsuneo Imamoto; Kazuhiro Yoshida; Keitaro Sugita
- Web page: https://patentgrep.com/patent/US7608709B2

## CPC

- C07F 15/008: {without a metal-carbon linkage}
- C07F 9/650952: {having the nitrogen atoms in the positions 1 and 4}
- C07F: ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM (metal-containing porphyrins C07D487/22)

## Abstract

An optically active 2,3-bis(dialkylphosphino)pyrazine derivative represented by formula (1) is disclosed. The pyrazine derivative is preferably a quinoxaline derivative represented by formula (2). In formula (1) and (2), R1 is preferably a t-butyl or adamantyl group, and R2 is preferably a methyl group. wherein R1 is a substitutable straight chain or branched alkyl group having 2 to 10 carbon atoms; R2 is a substitutable straight chain or branched alkyl group having fewer carbon atoms than R1; and R3 and R4, which may be the same or different, are each a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, or R3 and R4 are taken together to form a saturated or unsaturated ring. wherein R1 and R2 are as defined above; and R5 is a monovalent substituent.

## Claims

### Claim 1

An optically active 2,3-bis(dialkylphosphino)pyrazine represented by formula (1):
wherein R1 represents a straight chain or branched alkyl group having 2 to 10 carbon atoms and the alkyl group of R1 may be substituted with at least one monovalent substituent;
R2 represents a substituted or unsubstituted straight chain or branched alkyl group having fewer carbon atoms than R1;
and R3 and R4, which may be the same or different, each represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, or R3 and R4 are taken together to form a saturated or unsaturated ring.

### Claim 2 (depends on 1)

The pyrazine of claim 1, which is represented by formula (2):
wherein R1 and R2 are as defined in claim 1, and R5 represents a monovalent substituent.

### Claim 3 (depends on 1)

A process for producing the pyrazine of claim 1, comprising the steps of:
deprotonating a dialkylphosphine-borane represented by formula (4);
allowing the deprotonated dialkyiphosphine-borane to react with a 2,3-dihalogenopyrazine represented by formula (3) to carry out nucleophilic substitution; and then
deboranating the product:
wherein R3 and R4 are as defined in claim 1; and X represents a halogen atom:
wherein R1 and R2 are as defined in claim 1.

### Claim 4 (depends on 1)

pyrazine of claim 1, wherein the pyrazine is used as a ligand of a metal complex catalyst for asymmetric synthesis.

### Claim 5

An optically active 2,3bis(dialkylphosphino)pyrazine represented by formula (1):
wherein R1 is a tert-butyl group or an adamantyl group; R2 is a methyl group; and R3 and R4, which may be the same or different, each represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, or R3 and R4 are taken together to form a saturated or unsaturated ring.

### Claim 6 (depends on 5)

The pyrazine according to claim 5, wherein the pyrazine represented by formula (1) is one of (R,R)-2,3-bis(tert-butylmethylphosphino)quinoxaline, (R,R)-2, 3-bis(adamantylmethylphosphino)quinoxaline, (R,R)-2,3-bis(tert-butylmethylphosphino)pyrazine, and (R,R)-2,3-bis(adamantylmethylphosphino)pyrazine.

### Claim 7

An optically active 2,3-bis(dialkylphosphino)pyrazine represented by formula (1):
wherein R1 represents a straight chain or branched alkyl group having 2 to 10 carbon atoms; R2 represents a straight chain or branched alkyl group having fewer carbon atoms than R1; and R3 and R4, which may be the same or different, each represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, or R3 and R4 are taken together to form a saturated or unsaturated ring.