# US 7,612,239 B2 · Method for asymmetric alkynylation of alpha-imino esters

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- Number: US 7,612,239 B2
- Document ID: US7612239B2
- Status: Granted
- Kind: B2
- Application number: 11/913,773
- Filed: 2006-05-17
- Published: 2008-07-31
- Granted: 2009-11-03
- Earliest claimed: 2005-05-19
- Assignees: The Hong Kong Polytechnic University
- Inventors: Albert S Chan; Jian-Xin Ji; Jing Wu
- Web page: https://patentgrep.com/patent/US7612239B2

## CPC

- C07F 7/083: {Syntheses without formation of a Si-C bond}
- C07C 227/32: by stereospecific synthesis
- Y02P 20/55: Design of synthesis routes, e.g. reducing the use of auxiliary or protecting groups
- C07F: ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM (metal-containing porphyrins C07D487/22)
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

Method for the preparation of asymmetric alkynylated α-amino esters of the formula wherein R1 and R2 are independently optionally substituted alkyl cycloalkyl, aryl or heteroaryl, and Y is hydrogen or a nitrogen protecting group.

## Claims

### Claim 1

A method for the preparation of asymmetric alkynylated α-amino esters of the formula
wherein R1 and R2 are independently optionally substituted alkyl, cycloalkyl, aryl or heteroaryl, and Y is hydrogen or a nitrogen protecting group; which method comprises reacting an α-imino ester of formula
wherein R1 and Y have meanings as defined for formula III
with a terminal alkyne of formula
wherein R2 has meaning as defined for formula III.

### Claim 2 (depends on 1)

The method of claim 1, wherein said reacting is in the presence of a catalyst.

### Claim 3 (depends on 2)

The method of claim 2, wherein said reacting is in the presence of a catalytic amount of an amine base.

### Claim 4 (depends on 2)

The method of claim 2, wherein said amine base is PMP—N2.

### Claim 5 (depends on 2)

The method of claim 2, wherein said catalyst comprises a transition metal, a transition metal salt, or a transition metal complex.

### Claim 6 (depends on 5)

The method of claim 5, wherein said transition metal complex is selected from the group consisting of CuPF5.4MeCN and CuOTf.0.5C6H6.

### Claim 7 (depends on 5)

The method of claim 5, wherein said catalyst comprises a chiral ligand.

### Claim 8 (depends on 7)

The method of claim 7, wherein said chiral ligand is selected from the group consisting of
enantiomers thereof, and enantiomeric mixtures thereof.

### Claim 9 (depends on 1)

The method of claim 1, wherein R1 is alkyl.