The present invention provides a preparation method of (5-fluoro-2,3-dihydrobenzofuran-4-yl)methylamine or a salt thereof, which uses 4-fluoro-3-methylphenol as the starting material, and is carried out through the steps of bromination, O-alkylation, cyclization, bromination, azidation or ammonolysis, and reduction. The reaction route of the present invention has simple synthesis process, convenient operation, high yield, and is environmentally friendly. The prepared (5-fluoro-2,3-dihydrobenzofuran-4-yl)methylamine can be used as an intermediate in pharmaceuticals and fine chemicals.

A process for preparing a dienynal compound of the following general formula (2):
CH.sub.2═CHC≡CCH═CH(CH.sub.2).sub.nCHO  (2), wherein n represents an integer of 0 to 11, the process comprising a step of hydrolyzing a dialkoxyalkadienyne compound of the following general formula (1):
CH.sub.2═CHC≡CCH═CH(CH.sub.2).sub.nCH(OR.sup.1)(OR.sup.2)  (1) wherein R.sup.1 and R.sup.2 represent, independently of each other, a monovalent hydrocarbon group having 1 to 15 carbon atoms, preferably 1 to 8, more preferably 1 to 4, or R.sup.1 and R.sup.2 may be bonded to each other to form a divalent hydrocarbon group, R.sup.1-R.sup.2, having from 2 to 10 carbon atoms, and n represents an integer of 0 to 11, to obtain the dienynal compound (2). ##STR00001##

A process for preparing a dienynal compound of the following general formula (2):
CH.sub.2═CHC≡CCH═CH(CH.sub.2).sub.nCHO  (2), wherein n represents an integer of 0 to 11, the process comprising a step of hydrolyzing a dialkoxyalkadienyne compound of the following general formula (1):
CH.sub.2═CHC≡CCH═CH(CH.sub.2).sub.nCH(OR.sup.1)(OR.sup.2)  (1) wherein R.sup.1 and R.sup.2 represent, independently of each other, a monovalent hydrocarbon group having 1 to 15 carbon atoms, preferably 1 to 8, more preferably 1 to 4, or R.sup.1 and R.sup.2 may be bonded to each other to form a divalent hydrocarbon group, R.sup.1-R.sup.2, having from 2 to 10 carbon atoms, and n represents an integer of 0 to 11, to obtain the dienynal compound (2). ##STR00001##

A process for preparing a dienynal compound of the following general formula (2):
CH.sub.2═CHC≡CCH═CH(CH.sub.2).sub.nCHO  (2), wherein n represents an integer of 0 to 11, the process comprising a step of hydrolyzing a dialkoxyalkadienyne compound of the following general formula (1):
CH.sub.2═CHC≡CCH═CH(CH.sub.2).sub.nCH(OR.sup.1)(OR.sup.2)  (1) wherein R.sup.1 and R.sup.2 represent, independently of each other, a monovalent hydrocarbon group having 1 to 15 carbon atoms, preferably 1 to 8, more preferably 1 to 4, or R.sup.1 and R.sup.2 may be bonded to each other to form a divalent hydrocarbon group, R.sup.1-R.sup.2, having from 2 to 10 carbon atoms, and n represents an integer of 0 to 11, to obtain the dienynal compound (2). ##STR00001##

A process for preparing a dienynal compound of the following general formula (2): CH.sub.2CHCCCHCH(CH.sub.2).sub.nCHO (2), wherein n represents an integer of 0 to 11, the process comprising a step of hydrolyzing a dialkoxyalkadienyne compound of the following general formula (1): CH.sub.2CHCCCHCH(CH.sub.2).sub.nCH(OR.sup.1)(OR.sup.2) (1) wherein R.sup.1 and R.sup.2 represent, independently of each other, a monovalent hydrocarbon group having 1 to 15 carbon atoms, preferably 1 to 8, mere preferably 1 to 4, or R.sup.1 and R.sup.2 may be bonded to each other to form a divalent hydrocarbon group, R.sup.1-R.sup.2, having from 2 to 10 carbon atoms, and n represents an integer of 0 to 11, to obtain the dienynal compound (2).

##STR00001##

A process for preparing a dienynal compound of the following general formula (2): CH.sub.2CHCCCHCH(CH.sub.2).sub.nCHO (2), wherein n represents an integer of 0 to 11, the process comprising a step of hydrolyzing a dialkoxyalkadienyne compound of the following general formula (1): CH.sub.2CHCCCHCH(CH.sub.2).sub.nCH(OR.sup.1)(OR.sup.2) (1) wherein R.sup.1 and R.sup.2 represent, independently of each other, a monovalent hydrocarbon group having 1 to 15 carbon atoms, preferably 1 to 8, mere preferably 1 to 4, or R.sup.1 and R.sup.2 may be bonded to each other to form a divalent hydrocarbon group, R.sup.1-R.sup.2, having from 2 to 10 carbon atoms, and n represents an integer of 0 to 11, to obtain the dienynal compound (2).

##STR00001##

The present invention provides a process for preparing an 11-halo-3-undecene compound (7) in which X.sup.1 represents a halogen atom, the process comprising a step of subjecting a nucleophilic reagent, 3-hexenyl compound (5): in which M.sup.2 represents Li or MgZ.sup.2, wherein Z.sup.2 represents a halogen atom or a 3-hexenyl group, to a coupling reaction with a 1-halo-5-halopentane compound (6) in which X.sup.3 and X.sup.4 may be same with or different from each other and represent a halogen atom, to produce the 11-halo-3-undecene compound (7). The present invention also provides a process for preparing a 9-dodecenal compound (4): the process comprising a step of subjecting a nucleophilic reagent, 8-undecenyl compound (1) in which M.sup.1 represents Li or MgZ.sup.1, wherein Z.sup.1 represents a halogen atom or an 8-undecenyl group, and an orthoformic ester compound (2) in which R may be same with or different from each other and represents an alkyl group having 1 to 6 carbon atoms, to a nucleophilic substitution reaction to produce a 1,1-dialkoxy-9-dodecene compound (3) in which R are as defined above; and hydrolyzing the 1,1-dialkoxy-9-dodecene compound (3) thus obtained to produce the 9-dodecenal compound (4).

##STR00001##

The present invention provides a process for preparing an 11-halo-3-undecene compound (7) in which X.sup.1 represents a halogen atom, the process comprising a step of subjecting a nucleophilic reagent, 3-hexenyl compound (5): in which M.sup.2 represents Li or MgZ.sup.2, wherein Z.sup.2 represents a halogen atom or a 3-hexenyl group, to a coupling reaction with a 1-halo-5-halopentane compound (6) in which X.sup.3 and X.sup.4 may be same with or different from each other and represent a halogen atom, to produce the 11-halo-3-undecene compound (7). The present invention also provides a process for preparing a 9-dodecenal compound (4): the process comprising a step of subjecting a nucleophilic reagent, 8-undecenyl compound (1) in which M.sup.1 represents Li or MgZ.sup.1, wherein Z.sup.1 represents a halogen atom or an 8-undecenyl group, and an orthoformic ester compound (2) in which R may be same with or different from each other and represents an alkyl group having 1 to 6 carbon atoms, to a nucleophilic substitution reaction to produce a 1,1-dialkoxy-9-dodecene compound (3) in which R are as defined above; and hydrolyzing the 1,1-dialkoxy-9-dodecene compound (3) thus obtained to produce the 9-dodecenal compound (4).

##STR00001##

Disclosed is a method for preparing a 2-fluoroacrylate, comprising the steps of: (1) mixing a vinyl ether having the structure of formula A with dichloromonofluoromethane to yield a substituted cyclopropane compound having the structure of formula B; (2) mixing the substituted cyclopropane compound having the structure of formula B with R.sup.2OH to yield an acetal product having the structure of formula C, followed by hydrolysis to yield 2-fluoroacrylaldehyde having the structure of formula D; or reacting the substituted cyclopropane compound having the structure of formula B with water to yield 2-fluoroacrylaldehyde having the structure of formula D via hydrolysis; (3) oxidizing 2-fluoroacrylaldehyde having the structure of formula D to yield 2-fluoroacrylic acid having the structure of formula E; and (4) mixing 2-fluoroacrylic acid having the structure of formula E with R.sup.3OH to yield a 2-fluoroacrylate having the structure of formula F.

Disclosed is a method for preparing a 2-fluoroacrylate, comprising the steps of: (1) mixing a vinyl ether having the structure of formula A with dichloromonofluoromethane to yield a substituted cyclopropane compound having the structure of formula B; (2) mixing the substituted cyclopropane compound having the structure of formula B with R.sup.2OH to yield an acetal product having the structure of formula C, followed by hydrolysis to yield 2-fluoroacrylaldehyde having the structure of formula D; or reacting the substituted cyclopropane compound having the structure of formula B with water to yield 2-fluoroacrylaldehyde having the structure of formula D via hydrolysis; (3) oxidizing 2-fluoroacrylaldehyde having the structure of formula D to yield 2-fluoroacrylic acid having the structure of formula E; and (4) mixing 2-fluoroacrylic acid having the structure of formula E with R.sup.3OH to yield a 2-fluoroacrylate having the structure of formula F.