A process for the preparation of a compound of formula wherein: R is an alkynyl group; R 1 is alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkyl-alkyl, phenyl and phenylalkyl, it being possible in turn for all of the preceding groups to carry one or more identical or different halogen atoms; alkoxy; alkenyloxy; alkynyloxy; alkoxyalkyl; haloalkoxy; alkylthio; haloalkylthio; alkysulfonyl; formyl; alkanoyl; hydroxy; halogen; cyano; nitro; amino; alkylamino; dialkylamino; carboxyl; alkoxycarbonyl; alkenyloxycarbonyl; or alkynyloxycarbonyl; and n is an integer from 0 to 3, said process comprising: (i) the reaction of a compound of formula wherein R, R 1 and n are as indicated above for the compound of formula; m and m' are independently 0 or 1, and when either m and m' is 0, the other is 1, and A is an alkanediyl, alkenediyl or alkynediyl group containing at least two carbon atoms (and suitably having up to eight carbon atoms), optionally substituted by one or more groups independently selected from halogen, hydroxy, alkoxy, C 1-4 dialkylamino or cyano; or both m and m' are 1, and A is an alkanetriyl, alkenetriyl or alkynetriyl group containing at least three carbon atoms (and suitably having up to eight carbon atoms), optionally substituted by one or more groups independently selected from halogen, hydroxy, alkoxy, C 1-4 dialkylamino or cyano; and wherein if the group A contains three or more carbon atoms, one or more of the carbon atoms may each optionally be replaced with an oxygen atom, provided that there is at least one carbon atom between any two oxygen atoms in the molecule, with a compound of formula to give a compound of formula wherein R, R 1 and n are as indicated above for the compound of formula, and (ii) the reaction of the compound of formula with wherein L is a leaving group, to give the compound of formula. R is an alkynyl group; R 1 is alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkyl-alkyl, phenyl and phenylalkyl, it being possible in turn for all of the preceding groups to carry one or more identical or different halogen atoms; alkoxy; alkenyloxy; alkynyloxy; alkoxyalkyl; haloalkoxy; alkylthio; haloalkylthio; alkysulfonyl; formyl; alkanoyl; hydroxy; halogen; cyano; nitro; amino; alkylamino; dialkylamino; carboxyl; alkoxycarbonyl; alkenyloxycarbonyl; or alkynyloxycarbonyl; and n is an integer from 0 to 3, said process comprising: (i) the reaction of a compound of formula wherein R, R 1 and n are as indicated above for the compound of formula; m and m' are independently 0 or 1, and when either m and m' is 0, the other is 1, and A is an alkanediyl, alkenediyl or alkynediyl group containing at least two carbon atoms (and suitably having up to eight carbon atoms), optionally substituted by one or more groups independently selected from halogen, hydroxy, alkoxy, C 1-4 dialkylamino or cyano; or both m and m' are 1, and A is an alkanetriyl, alkenetriyl or alkynetriyl group containing at least three carbon atoms (and suitably having up to eight carbon atoms), optionally substituted by one or more groups independently selected from halogen, hydroxy, alkoxy, C 1-4 dialkylamino or cyano; and wherein if the group A contains three or more carbon atoms, one or more of the carbon atoms may each optionally be replaced with an oxygen atom, provided that there is at least one carbon atom between any two oxygen atoms in the molecule, with a compound of formula to give a compound of formula wherein R, R 1 and n are as indicated above for the compound of formula, and (ii) the reaction of the compound of formula with wherein L is a leaving group, to give the compound of formula. (i) the reaction of a compound of formula wherein R, R 1 and n are as indicated above for the compound of formula; m and m' are independently 0 or 1, and when either m and m' is 0, the other is 1, and A is an alkanediyl, alkenediyl or alkynediyl group containing at least two carbon atoms (and suitably having up to eight carbon atoms), optionally substituted by one or more groups independently selected from halogen, hydroxy, alkoxy, C 1-4 dialkylamino or cyano; or both m and m' are 1, and A is an alkanetriyl, alkenetriyl or alkynetriyl group containing at least three carbon atoms (and suitably having up to eight carbon atoms), optionally substituted by one or more groups independently selected from halogen, hydroxy, alkoxy, C 1-4 dialkylamino or cyano; and wherein if the group A contains three or more carbon atoms, one or more of the carbon atoms may each optionally be replaced with an oxygen atom, provided that there is at least one carbon atom between any two oxygen atoms in the molecule, with a compound of formula to give a compound of formula wherein R, R 1 and n are as indicated above for the compound of formula, and (ii) the reaction of the compound of formula with wherein L is a leaving group, to give the compound of formula.