Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2001-11-16
2004-04-20
Ramsuer, Robert W. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
active
06723860
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a novel 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one that can be used as a starting material or an intermediate for synthesizing a pharmaceutical product or an agricultural chemical and as a starting material for synthesizing other fine chemical products, and a process for producing the same. 3-Diphenylmethyl-7a-methoxy-6-methyl-4H-pyrano[3,2-d]-oxazol-2(3H)-one obtainable by the present invention can be led to 5-methylproline methyl ester that is useful as a starting material or an intermediate for synthesis of pharmaceutical products or agricultural chemicals, for example, by reacting it with trifluoroacetic acid in methylene chloride, and subsequently reacting with hydrogen in the presence of a Pd/C catalyst (as later described in Reference Example 1).
2. Prior Art
It has been conventionally known a method for producing 4-alkoxycarbonyl-2-oxazolidinone by reacting 5-alkoxy-2(3H)-oxazolones with aldehydes in an organic solvent in the presence of a Lewis acid (WO 99/02508). However, there has been known at all neither a process in which a 5-alkoxy-2(3H)-oxazolone is reacted with an &agr;,&bgr;-unsaturated ketone in an organic solvent in the presence of a Lewis acid, nor 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one obtainable by the process.
That is, an object of the present invention is to provide a novel 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one that is useful as a starting material for synthesis of pharmaceutical products or agricultural chemicals, and for synthesis of other fine chemicals, and also to provide a process for producing the same.
SUMMARY OF THE INVENTION
The present invention relates to a 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one represented by the formula (I):
wherein R
1
represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or an aralkyl group; R
2
represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or an aralkyl group; R
3
represents an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group or an aralkyl group, provided that a 2-alkenyl group is excluded from the alkenyl group of R
3
; and R
4
represents an alkyl group, an aryl group, an alkoxycarbonyl group or a cyano group.
The present invention also relates to a process for producing a 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one represented by the formula (I):
wherein R
1
, R
2
, R
3
and R
4
are the same as defined above, which comprises reacting a 5-alkoxy-2(3H)-oxazolone represented by the formula (II):
wherein R
1
, R
2
and R
3
are the same as defined above, with an &agr;, &bgr;-unsaturated ketone represented by the formula (III):
wherein R
4
is the same as defined above, in an organic solvent in the presence of a Lewis acid.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following, the embodiments of the present invention are explained in detail.
The 7a-alkoxy-4H-pyrano[3,2-d]-oxazol-2(3H)-one of the present invention is represented by the formula (I) and may be referred to as a compound (I) hereinafter.
An alkyl group represented by R
1
in the compound (1) is a straight, branched or cyclic alkyl group, example of which include a straight, branched or cyclic alkyl group having 1 to 10 carbon atoms such as methyl, ethyl, propyl (including an isomer), butyl (including each isomer), pentyl (including each isomer), hexyl (including each isomer), heptyl (including each isomer), octyl (including each isomer), nonyl (including each isomer), decyl (including each isomer), cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl and menthyl groups. Preferably, they are straight, branched or cyclic alkyl groups having 1 to 6 carbon atoms, and more preferably, they are each group of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl.
An alkenyl group represented by R
1
in the compound (I) is a straight, branched or cyclic alkenyl group, example of which include a straight, branched or cyclic alkenyl group having 2 to 10 carbon atoms such as vinyl, propenyl (including an isomer), butenyl (including each isomer), pentenyl (including each isomer), hexenyl (including each isomer), heptenyl (including each isomer), octenyl (including each isomer), nonenyl (including each isomer), decenyl (including each isomer) groups, etc. Preferred are straight, branched or cyclic alkenyl groups having 2 to 6 carbon atoms, and more preferred are vinyl, propenyl, 1-butenyl, 2-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, cyclopentenyl and cyclohexenyl groups.
An aryl group represented by R
1
in the compound (1) is either (1) an aryl group having no substituent or (2) an aryl group having one or more substituents.
As the above-mentioned (1) aryl group having no substituent, there are exemplified by each group of phenyl, naphthyl, anthracenyl, phenanthryl, etc. Among them, preferred is each group of phenyl and naphthyl, and more preferred is a phenyl group.
As an aryl group of the above-mentioned (2) aryl group having one or more substituents, it means the same as defined for the aryl group of (1) the aryl group having no substituent. Preferred is each group of phenyl and naphthyl, and more preferred is a phenyl group.
As a substituent for (2) the aryl group having one or more substituents, there are exemplified a straight or branched alkyl group having 1 to 6 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, butyl (including each isomer), pentyl (including each isomer), hexyl (including each isomer) groups, etc.; each group of hydroxyl; nitro; cyano; a halogen atom (fluorine, chlorine, bromine and iodine atoms); a straight or branched alkoxy group having 1 to 6 carbon atoms such as methoxy, ethoxy, propoxy (including each isomer), butoxy (including each isomer), pentyloxy (including each isomer), hexyloxy (including each isomer) groups, etc.; an amino group which may be substituted by a straight or branched alkyl group having 1 to 6 carbon atoms such as methyl, ethyl, propyl groups, etc.; an aralkyloxy group such as a benzyloxy group, etc.; a trimethylsilyloxy group; etc. Preferred are an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro, cyano, halogen atom, an aralkyloxy and trimethylsilyloxy group, and more preferred are methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, methoxy, ethoxy, and tert-butoxy groups, fluorine, chlorine and bromine atoms, nitro and benzyloxy groups. These substituents are not limited in numbers or positions and a plural number of substituents which may be the same or different may substitute.
An aralkyl group represented by R
1
in the compound (1) is either (3) an aralkyl group having no substituent or (4) an aralkyl group having one or more substituents.
As the above-mentioned (3) aralkyl group having no substituent, examples may include each group of benzyl, 1-phenylethyl, 2-phenylethyl, 1-phenylpropyl, 3-phenylpropyl, 1-(1-naphthyl)ethyl, 1-naphthylmethyl, 1-(2-naphthyl)ethyl, etc. Preferred examples may include each group of benzyl, 1-phenylethyl, 2-phenylethyl, 1-(1-naphthyl)ethyl, 1-(2-naphthyl)ethyl, 1-naphthylmethyl, 1-phenylpropyl, diphenylmethyl and trityl. And more preferred are each group of benzyl, 1-phenylethyl, 1-(1-naphthyl)ethyl, 1-naphthylmethyl and diphenylmethyl.
An aralkyl group of the above-mentioned (4) aralkyl group having one or more substituents has the same meanings as defined for the aralkyl group of (3) the aralkyl group having no substituent. Preferred examples may include each group of benzyl, 1-phenylethyl, 2-phenylethyl, 1-(1-naphthyl)ethyl, 1-(2-naphthyl)ethyl, 1-naphthylmethyl, 1-phenylpropyl and diphenylmethyl. And more preferred are each group of benzyl, 1-phenylethyl, 1-(1-naphthyl)ethyl, 1-naphthylmethyl and diphenylmethyl.
A substituent for (4) the aralkyl group having one or more substituents may include a straight or branched alkyl group having 1 to 6 carbon atoms such
Ataka Kikuo
Honma Takashi
Miyata Hiroyuki
Yamamoto Yasuhito
Anderson Rebecca
Ramsuer Robert W.
UBE Industries Ltd.
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