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##

Disclosed are a salt represented by formula (I), an acid generator, and a resist composition comprising the same:

##STR00001##

wherein R.sup.1 and R.sup.2 each represent a hydroxy group, *—O—R.sup.10, *—O-L.sup.10-CO—O—R.sup.10; L.sup.10 represents an alkanediyl group; R.sup.10 represents an acid-labile group; R.sup.4, R.sup.5, R.sup.7 and R.sup.8 each represent a halogen atom, a haloalkyl group or a hydrocarbon group; A.sup.1 and A.sup.2 each represent a hydrocarbon group, the hydrocarbon group may have a substituent, and —CH.sub.2— included in the hydrocarbon group may be replaced by —O—, —CO—, —S— or —SO.sub.2—; m1 represents an integer of 1 to 5, m2 and m8 represent an integer of 0 to 5, m4, m5 and m7 represent an integer of 0 to 4, 1≤m1+m7≤5, 0≤m2+m8≤5; and AI.sup.− represents an organic anion.

The present invention relates to a 6-hydroxy-3-hexenyl alkoxymethyl ether compound of the following general formula (1): HOCH.sub.2CH.sub.2CH═CHCH.sub.2CH.sub.2OCH.sub.2OCH.sub.2R′ (1), R.sup.1 representing a hydrogen atom, an n-alkyl group having 1 to 9 carbon atoms, or a phenyl group; and also relates to a process for preparing a 3,13-octadecadien-1-ol compound of the following formula (6): CH.sub.3(CH.sub.2).sub.3CH═CH(CH.sub.2).sub.8CH═CHCH.sub.2CH.sub.2OH (6) from the 6-hydroxy-3-hexenyl alkoxymethyl ether compound (1).

The present invention relates to a 6-hydroxy-3-hexenyl alkoxymethyl ether compound of the following general formula (1): HOCH.sub.2CH.sub.2CH═CHCH.sub.2CH.sub.2OCH.sub.2OCH.sub.2R′ (1), R.sup.1 representing a hydrogen atom, an n-alkyl group having 1 to 9 carbon atoms, or a phenyl group; and also relates to a process for preparing a 3,13-octadecadien-1-ol compound of the following formula (6): CH.sub.3(CH.sub.2).sub.3CH═CH(CH.sub.2).sub.8CH═CHCH.sub.2CH.sub.2OH (6) from the 6-hydroxy-3-hexenyl alkoxymethyl ether compound (1).

The present invention relates to a process for preparing a (4Z)-11,11-dialkoxy-4-undecenyltriarylphosphonium halide compound of the following general formula (3-Z): wherein Y represents a halogen atom, Ar represents, independently of each other, an aryl group, and R.sup.1 and R.sup.2 represent, independently of each other, a monovalent hydrocarbon group having 1 to 15 carbon atoms, or R.sup.1 and R.sup.2 may form together a divalent hydrocarbon group, R.sup.1-R.sup.2, having 2 to 10 carbon atoms, the process comprising: subjecting a (7Z)-11-halo-1,1-dialkoxy-7-undecene compound of the following general formula (1-Z): wherein X.sup.1 represents a halogen atom, and R.sup.1 and R.sup.2 are as defined above to a phosphonium salt formation reaction with a phosphine compound of the following general formula (2): wherein Ar is as defined above to form the (4Z)-11,11-dialkoxy-4-undecenyltriarylphosphonium halide compound (3-Z).

##STR00001##

The present invention also relates to a compound of the following general formula (A): L(CH.sub.2).sub.3CH═CH(CH.sub.2).sub.5CH(OR.sup.1)(OR.sup.2) (A) wherein R.sup.1 and R.sup.2 are as defined above.

The present invention relates to a process for preparing a (4Z)-11,11-dialkoxy-4-undecenyltriarylphosphonium halide compound of the following general formula (3-Z): wherein Y represents a halogen atom, Ar represents, independently of each other, an aryl group, and R.sup.1 and R.sup.2 represent, independently of each other, a monovalent hydrocarbon group having 1 to 15 carbon atoms, or R.sup.1 and R.sup.2 may form together a divalent hydrocarbon group, R.sup.1-R.sup.2, having 2 to 10 carbon atoms, the process comprising: subjecting a (7Z)-11-halo-1,1-dialkoxy-7-undecene compound of the following general formula (1-Z): wherein X.sup.1 represents a halogen atom, and R.sup.1 and R.sup.2 are as defined above to a phosphonium salt formation reaction with a phosphine compound of the following general formula (2): wherein Ar is as defined above to form the (4Z)-11,11-dialkoxy-4-undecenyltriarylphosphonium halide compound (3-Z).

##STR00001##

The present invention also relates to a compound of the following general formula (A): L(CH.sub.2).sub.3CH═CH(CH.sub.2).sub.5CH(OR.sup.1)(OR.sup.2) (A) wherein R.sup.1 and R.sup.2 are as defined above.

The present invention relates to a process for preparing a (4Z)-11,11-dialkoxy-4-undecenyltriarylphosphonium halide compound of the following general formula (3-Z): wherein Y represents a halogen atom, Ar represents, independently of each other, an aryl group, and R.sup.1 and R.sup.2 represent, independently of each other, a monovalent hydrocarbon group having 1 to 15 carbon atoms, or R.sup.1 and R.sup.2 may form together a divalent hydrocarbon group, R.sup.1-R.sup.2, having 2 to 10 carbon atoms, the process comprising: subjecting a (7Z)-11-halo-1,1-dialkoxy-7-undecene compound of the following general formula (1-Z): wherein X.sup.1 represents a halogen atom, and R.sup.1 and R.sup.2 are as defined above to a phosphonium salt formation reaction with a phosphine compound of the following general formula (2): wherein Ar is as defined above to form the (4Z)-11,11-dialkoxy-4-undecenyltriarylphosphonium halide compound (3-Z).

##STR00001##

The present invention also relates to a compound of the following general formula (A): L(CH.sub.2).sub.3CH═CH(CH.sub.2).sub.5CH(OR.sup.1)(OR.sup.2) (A) wherein R.sup.1 and R.sup.2 are as defined above.

Provided are a method for producing a terminal conjugated dienal compound without an oxidation reaction and a terminal hydroxyacetal compound useful as an intermediate in the method. More specifically, provided are a method for producing an (E)-dienal compound comprising the steps of: a metalation reaction of an alkynal acetal compound (1) to obtain an organic metal compound (2), an addition reaction of (2) to ethylene oxide to obtain a hydroxyalkynal acetal compound (3), a reduction reaction of (3) to obtain an (E)-hydroxyalkenal acetal compound (4), a functional group conversion reaction of (4) to obtain an (E)-alkenal acetal compound (5) having a leaving group X, an elimination reaction of (5) to obtain an (E)-dienal acetal compound (6), and a hydrolysis reaction of (6) to obtain the (E)-dienal compound (7); and others.

##STR00001##

Provided are a method for producing a terminal conjugated dienal compound without an oxidation reaction and a terminal hydroxyacetal compound useful as an intermediate in the method. More specifically, provided are a method for producing an (E)-dienal compound comprising the steps of: a metalation reaction of an alkynal acetal compound (1) to obtain an organic metal compound (2), an addition reaction of (2) to ethylene oxide to obtain a hydroxyalkynal acetal compound (3), a reduction reaction of (3) to obtain an (E)-hydroxyalkenal acetal compound (4), a functional group conversion reaction of (4) to obtain an (E)-alkenal acetal compound (5) having a leaving group X, an elimination reaction of (5) to obtain an (E)-dienal acetal compound (6), and a hydrolysis reaction of (6) to obtain the (E)-dienal compound (7); and others.

##STR00001##