The present invention relates to a process for preparing a process for preparing a (2-cyclopentenyl)acetate ester compound of the following general formula (2): wherein R represents a linear or branched alkyl group having 1 to 4 carbon atoms, Y represents a halogen atom, and X.sub.1 to X.sub.7 represent, independently of each other, a hydrogen atom or a methyl group, with the proviso that one to three among X.sub.1 to X.sub.7 represent a methyl group and the remaining represent a hydrogen atom, the process comprising: subjecting a haloacetaldehyde alkyl 2-cyclopentenyl acetal compound of the following general formula (1): wherein R is as defined above, X.sub.1 to X.sub.7 are as selected in the general formula (2), respectively, and Y represents a halogen atom, to a dehydrohalogenation reaction in the presence of a base, followed by a rearrangement reaction to form the (2-cyclopentenyl)acetate ester compound (2) and a process for preparing a (2-cyclopentenyl)acetic acid compound of the following general formula (3): wherein X.sub.1 to X.sub.7 are as selected in the general formula (1), respectively, the process comprising hydrolyzing the (2-cyclopentenyl)acetate ester compound (2) to form the (2-cyclopentenyl)acetic acid compound (3). The present invention relates also to the novel compound, haloacetaldehyde alkyl 2-cyclopentenyl acetal compound (1).

##STR00001##

The present invention relates to a process for preparing a process for preparing a (2-cyclopentenyl)acetate ester compound of the following general formula (2): wherein R represents a linear or branched alkyl group having 1 to 4 carbon atoms, Y represents a halogen atom, and X.sub.1 to X.sub.7 represent, independently of each other, a hydrogen atom or a methyl group, with the proviso that one to three among X.sub.1 to X.sub.7 represent a methyl group and the remaining represent a hydrogen atom, the process comprising: subjecting a haloacetaldehyde alkyl 2-cyclopentenyl acetal compound of the following general formula (1): wherein R is as defined above, X.sub.1 to X.sub.7 are as selected in the general formula (2), respectively, and Y represents a halogen atom, to a dehydrohalogenation reaction in the presence of a base, followed by a rearrangement reaction to form the (2-cyclopentenyl)acetate ester compound (2) and a process for preparing a (2-cyclopentenyl)acetic acid compound of the following general formula (3): wherein X.sub.1 to X.sub.7 are as selected in the general formula (1), respectively, the process comprising hydrolyzing the (2-cyclopentenyl)acetate ester compound (2) to form the (2-cyclopentenyl)acetic acid compound (3). The present invention relates also to the novel compound, haloacetaldehyde alkyl 2-cyclopentenyl acetal compound (1).

##STR00001##

The present invention provides a process for preparing an alkoxymethyl alkynyl ether compound having a terminal triple bond of the following formula (4): H—C≡C(CH.sub.2).sub.aOCH.sub.2OCH.sub.2R (4), wherein R represents a hydrogen atom, an n-alkyl group having 1 to 9 carbon atoms, or a phenyl group, and “a” represents an integer of 1 to 10, the method comprising subjecting an alkynol compound having a terminal triple bond of the following formula (1): H—C≡C(CH.sub.2).sub.aOH (1), wherein “a” is as defined above, to an alkoxymethylation with a halomethyl alkyl ether compound of the following formula (3): RCH.sub.2OCH.sub.2X (3), wherein X represents a halogen atom, and R is as defined above, in the presence of a dialkylaniline compound of the following formula (2): [CH.sub.3(CH.sub.2).sub.b][CH.sub.3(CH.sub.2).sub.c]NC.sub.6H.sub.5 (2), wherein b and c represent, independently of each other, an integer of 0 to 9, to form the alkoxymethyl alkynyl ether compound (4) having a terminal triple bond.

The present invention provides a process for preparing an alkoxymethyl alkynyl ether compound having a terminal triple bond of the following formula (4): H—C≡C(CH.sub.2).sub.aOCH.sub.2OCH.sub.2R (4), wherein R represents a hydrogen atom, an n-alkyl group having 1 to 9 carbon atoms, or a phenyl group, and “a” represents an integer of 1 to 10, the method comprising subjecting an alkynol compound having a terminal triple bond of the following formula (1): H—C≡C(CH.sub.2).sub.aOH (1), wherein “a” is as defined above, to an alkoxymethylation with a halomethyl alkyl ether compound of the following formula (3): RCH.sub.2OCH.sub.2X (3), wherein X represents a halogen atom, and R is as defined above, in the presence of a dialkylaniline compound of the following formula (2): [CH.sub.3(CH.sub.2).sub.b][CH.sub.3(CH.sub.2).sub.c]NC.sub.6H.sub.5 (2), wherein b and c represent, independently of each other, an integer of 0 to 9, to form the alkoxymethyl alkynyl ether compound (4) having a terminal triple bond.

The present invention provides a process for preparing an alkoxymethyl alkynyl ether compound having a terminal triple bond of the following formula (4): H—C≡C(CH.sub.2).sub.aOCH.sub.2OCH.sub.2R (4), wherein R represents a hydrogen atom, an n-alkyl group having 1 to 9 carbon atoms, or a phenyl group, and “a” represents an integer of 1 to 10, the method comprising subjecting an alkynol compound having a terminal triple bond of the following formula (1): H—C≡C(CH.sub.2).sub.aOH (1), wherein “a” is as defined above, to an alkoxymethylation with a halomethyl alkyl ether compound of the following formula (3): RCH.sub.2OCH.sub.2X (3), wherein X represents a halogen atom, and R is as defined above, in the presence of a dialkylaniline compound of the following formula (2): [CH.sub.3(CH.sub.2).sub.b][CH.sub.3(CH.sub.2).sub.c]NC.sub.6H.sub.5 (2), wherein b and c represent, independently of each other, an integer of 0 to 9, to form the alkoxymethyl alkynyl ether compound (4) having a terminal triple bond.

The present invention relates to a process for preparing a (2-cyclopentenyl)acetate ester compound of general formula (2) as described herein, the process comprising: subjecting a haloacetaldehyde alkyl 2-cyclopentenyl acetal compound of general formula (1) as described herein to a dehydrohalogenation reaction in the presence of a base, followed by a rearrangement reaction to form the (2-cyclopentenyl)acetate ester compound of general formula (2). The present invention also relates to a process for preparing a (2-cyclopentenyl)acetic acid compound of general formula (3) as described herein, the process comprising hydrolyzing the (2-cyclopentenyl)acetate ester compound of general formula (2) to form the (2-cyclopentenyl)acetic acid compound of general formula (3). The present invention also relates to a haloacetaldehyde alkyl 2-cyclopentenyl acetal compound of general formula (1) as described herein.

The present invention relates to a process for preparing a (2-cyclopentenyl)acetate ester compound of general formula (2) as described herein, the process comprising: subjecting a haloacetaldehyde alkyl 2-cyclopentenyl acetal compound of general formula (1) as described herein to a dehydrohalogenation reaction in the presence of a base, followed by a rearrangement reaction to form the (2-cyclopentenyl)acetate ester compound of general formula (2). The present invention also relates to a process for preparing a (2-cyclopentenyl)acetic acid compound of general formula (3) as described herein, the process comprising hydrolyzing the (2-cyclopentenyl)acetate ester compound of general formula (2) to form the (2-cyclopentenyl)acetic acid compound of general formula (3). The present invention also relates to a haloacetaldehyde alkyl 2-cyclopentenyl acetal compound of general formula (1) as described herein.

The present invention provides a process for preparing an alkoxymethyl alkynyl ether compound having a terminal triple bond of the following formula (4): H—C≡C(CH.sub.2).sub.aOCH.sub.2OCH.sub.2R (4), wherein R represents a hydrogen atom, an n-alkyl group having 1 to 9 carbon atoms, or a phenyl group, and “a” represents an integer of 1 to 10, the method comprising subjecting an alkynol compound having a terminal triple bond of the following formula (1): H—C≡C(CH.sub.2).sub.aOH (1), wherein “a” is as defined above, to an alkoxymethylation with a halomethyl alkyl ether compound of the following formula (3): RCH.sub.2OCH.sub.2X (3), wherein X represents a halogen atom, and R is as defined above, in the presence of a dialkylaniline compound of the following formula (2): [CH.sub.3(CH.sub.2).sub.b][CH.sub.3(CH.sub.2).sub.c]NC.sub.6H.sub.5 (2), wherein b and c represent, independently of each other, an integer of 0 to 9, to form the alkoxymethyl alkynyl ether compound (4) having a terminal triple bond.

The present invention provides a process for preparing an alkoxymethyl alkynyl ether compound having a terminal triple bond of the following formula (4): H—C≡C(CH.sub.2).sub.aOCH.sub.2OCH.sub.2R (4), wherein R represents a hydrogen atom, an n-alkyl group having 1 to 9 carbon atoms, or a phenyl group, and “a” represents an integer of 1 to 10, the method comprising subjecting an alkynol compound having a terminal triple bond of the following formula (1): H—C≡C(CH.sub.2).sub.aOH (1), wherein “a” is as defined above, to an alkoxymethylation with a halomethyl alkyl ether compound of the following formula (3): RCH.sub.2OCH.sub.2X (3), wherein X represents a halogen atom, and R is as defined above, in the presence of a dialkylaniline compound of the following formula (2): [CH.sub.3(CH.sub.2).sub.b][CH.sub.3(CH.sub.2).sub.c]NC.sub.6H.sub.5 (2), wherein b and c represent, independently of each other, an integer of 0 to 9, to form the alkoxymethyl alkynyl ether compound (4) having a terminal triple bond.

The present invention provides a process for preparing an alkoxymethyl alkynyl ether compound having a terminal triple bond of the following formula (4): H—C≡C(CH.sub.2).sub.aOCH.sub.2OCH.sub.2R (4), wherein R represents a hydrogen atom, an n-alkyl group having 1 to 9 carbon atoms, or a phenyl group, and “a” represents an integer of 1 to 10, the method comprising subjecting an alkynol compound having a terminal triple bond of the following formula (1): H—C≡C(CH.sub.2).sub.aOH (1), wherein “a” is as defined above, to an alkoxymethylation with a halomethyl alkyl ether compound of the following formula (3): RCH.sub.2OCH.sub.2X (3), wherein X represents a halogen atom, and R is as defined above, in the presence of a dialkylaniline compound of the following formula (2): [CH.sub.3(CH.sub.2).sub.b][CH.sub.3(CH.sub.2).sub.c]NC.sub.6H.sub.5 (2), wherein b and c represent, independently of each other, an integer of 0 to 9, to form the alkoxymethyl alkynyl ether compound (4) having a terminal triple bond.