# US 6,723,860 B2 · 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one and process for producing the same

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- Number: US 6,723,860 B2
- Document ID: US6723860B2
- Status: Granted
- Kind: B2
- Application number: 09/988,042
- Filed: 2001-11-16
- Published: 2002-06-13
- Granted: 2004-04-20
- Earliest claimed: 2000-11-16
- Assignees: Ube Industries, Ltd.
- Inventors: Hiroyuki Miyata; Takashi Honma; Yasuhito Yamamoto; Kikuo Ataka
- Web page: https://patentgrep.com/patent/US6723860B2

## CPC

- C07D 498/04: Ortho-condensed systems
- C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08)

## Abstract

The present invention provides a novel 7a-alkoxy-4H-pyrano-[3,2-d]-oxazol-2(3H)-one represented by the formula (I): wherein R1 and R2 each represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or an aralkyl group; R3 represents an alkyl group, a cyclo-alkyl group, an alkenyl group, an aryl group or an aralkyl group, provided that a 2-alkenyl group is excluded from the alkenyl group of R3; and R4 represents an alkyl group, an aryl group, an alkoxycarbonyl group or a cyano group, and a process for producing the same which comprises reacting 5-alkoxy-2(3H)-oxazolone with an α,β-unsaturated ketone in the presence of a Lewis acid in a solvent.

## Claims

### Claim 1

A 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one represented by the formula (I):
wherein R1 represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or an aralkyl group; R2 represents a hydrogen atom; R3 is a methyl group; and R4 represents a methyl group.

### Claim 2 (depends on 1)

The 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one according to claim 1, wherein
R1 represents an alkyl group, a phenyl group or an aralkyl group, R2 represents a hydrogen atom, R3 is a methyl group, and R4 represents a methyl group.

### Claim 3 (depends on 1)

The 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one according to claim 1, wherein R1 represents a benzyl group, a 1-phenylethyl group, a diphenylmethyl group, a phenyl group, a (1-naphthyl)methyl group or a 1-(1-naphthyl)ethyl group, R2 represents a hydrogen atom, R4 represents a methyl group.

### Claim 4 (depends on 1)

The 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one according to claim 1, wherein the 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one represented by the formula (I) is at least one compound selected from the group consisting of:
3-diphenylmethyl-7a-ethoxy-6-methyl-4H-pyrano[3,2-d]-oxazol-2(3H)-one;
3-diphenylmethyl-7a-methoxy-6-methyl-4H-pyrano[3,2-d]-oxazol-2(3H)-one;
3-diphenylmethyl-3a-methyl-7a-methoxy-6-methyl-4H-pyrano[3,2-d]-oxazol-2(3H)-one;
3-(1-phenylethyl)-7a-methoxy-6-methyl-4H-pyrano[3,2-d]-oxazol-2(3H)-one;
3-benzyl-7a-methoxy-6-methyl-4H-pyrano[3,2-d]-oxazol-2(3H)-one;
3-(1-(1-naphthyl)ethyl)-7a-methoxy-6-methyl-4H-pyrano[3,2-d]-oxazol-2(3H)-one.

### Claim 5

A process for producing a 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one represented by the formula (I):
wherein R1 represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or an aralkyl group; R2 represents a hydrogen atom; R3 represents a methyl group; and R4 represents a methyl group, which comprises reacting a 5-alkoxy-2(3H)-oxazolone represented by the formula (II):
wherein R1, R2 and R3 are the same as defined above, with an α, β-unsaturated ketone represented by the formula (III):
wherein R4 is the same as defined above, in an organic solvent in the presence of a Lewis acid.

### Claim 6 (depends on 5)

The process for producing a 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one according to claim 5, wherein the Lewis acid is represented by the formula (IV):
R5R6R7SiOTf (IV)
wherein R5, R6 and R7 each independently represent an alkyl group having 1 to 6 carbon atoms and Tf represents a trifluoromethanesulfonyl group.

### Claim 7 (depends on 1)

The 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one according to claim 1, wherein R1 is an alkyl group, an aralkyl group or a phenyl group, R2 is a hydrogen atom, R3 is a methyl group, and R4 is a methyl group.

### Claim 8 (depends on 1)

The 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one according to claim 1, wherein R1 is an alkyl group having 1 to 6 carbon atoms, an aralkyl group or a phenyl group, R2 is a hydrogen atom, R3 is a methyl group, and R4 is a methyl group.

### Claim 9

3-diphenylmethyl-7a-methoxy-6-methyl-4H-pyrano[3,2-d]oxazol-2(3H)-one.