A compound of formula Ia wherein W is -C(U 1)(U 2)-C≡H, U 1 and U 2 being independently selected from hydrogen and deuterium; A is selected from the group consisting of phenyl, furanyl, in particular furan-2-yl, furan-3-yl, (G 4 -(C 1- C 3)alkyl)phenyl, (G 4 -(C 1 -C 3)alkoxy)phenyl, whereas phenyl and furanyl are optionally substituted by one or more groups selected from: halogen, hydroxyl, nitro, (C 1 -C 6)carbonyl, cyano, nitrile, trifluoromethyl, (C 1 -C 6)sulfonyl, (C 1 -C 6)alkyl, (C 1 -C 6)alkoxy and (C 1 -C 6)sulfanyl, G 1, G 2, G 3 and G 4 are independently and individually, at each occurrence, selected from the group consisting of hydrogen, (C 1 -C 4)alkyl, preferably methyl, L, and -(C 1 -C 6)alkyl-L, with the proviso that exactly one of G 1 -G 4 in formula Ia are selected from L and -(C 1 -C 6)alkyl-L, L is a leaving group selected from the group consisting of halo, in particular chloro, bromo, iodo, mesyloxy, tosyloxy, trifluormethylsulfonyloxy, nona-fluorobutylsulfonyloxy, (4-bromo-phenyl)sulfonyloxy, (4-nitro-phenyl)sulfonyloxy, (2-nitro-phenyl)sulfonyloxy, (4-isopropyl-phenyl)sulfonyloxy, (2,4,6-tri-isopropyl-phenyl)sulfonyloxy, (2,4,6-trimethyl-phenyl)sulfonyloxy, (4- tert butyl-phenyl)sulfonyloxy, and (4-methoxy-phenyl)sulfonyloxy, wherein n is 1-3, and wherein m is 0-1, including all isomeric forms of said compound, including but not limited to enantiomers and diastereoisomers as well as racemic mixtures, with the proviso that a compound of formula (Ia) is not W = -CH 2 -C≡CH, A = phenyl, m = 0, n = 1, G1 = methyl, G2 = chloro, G3= hydrogen. and any pharmaceutically acceptable salt, ester, amide. W is -C(U 1)(U 2)-C≡H, U 1 and U 2 being independently selected from hydrogen and deuterium; A is selected from the group consisting of phenyl, furanyl, in particular furan-2-yl, furan-3-yl, (G 4 -(C 1- C 3)alkyl)phenyl, (G 4 -(C 1 -C 3)alkoxy)phenyl, whereas phenyl and furanyl are optionally substituted by one or more groups selected from: halogen, hydroxyl, nitro, (C 1 -C 6)carbonyl, cyano, nitrile, trifluoromethyl, (C 1 -C 6)sulfonyl, (C 1 -C 6)alkyl, (C 1 -C 6)alkoxy and (C 1 -C 6)sulfanyl, G 1, G 2, G 3 and G 4 are independently and individually, at each occurrence, selected from the group consisting of hydrogen, (C 1 -C 4)alkyl, preferably methyl, L, and -(C 1 -C 6)alkyl-L, with the proviso that exactly one of G 1 -G 4 in formula Ia are selected from L and -(C 1 -C 6)alkyl-L, L is a leaving group selected from the group consisting of halo, in particular chloro, bromo, iodo, mesyloxy, tosyloxy, trifluormethylsulfonyloxy, nona-fluorobutylsulfonyloxy, (4-bromo-phenyl)sulfonyloxy, (4-nitro-phenyl)sulfonyloxy, (2-nitro-phenyl)sulfonyloxy, (4-isopropyl-phenyl)sulfonyloxy, (2,4,6-tri-isopropyl-phenyl)sulfonyloxy, (2,4,6-trimethyl-phenyl)sulfonyloxy, (4- tert butyl-phenyl)sulfonyloxy, and (4-methoxy-phenyl)sulfonyloxy, wherein n is 1-3, and wherein m is 0-1, including all isomeric forms of said compound, including but not limited to enantiomers and diastereoisomers as well as racemic mixtures, with the proviso that a compound of formula (Ia) is not W = -CH 2 -C≡CH, A = phenyl, m = 0, n = 1, G1 = methyl, G2 = chloro, G3= hydrogen. and any pharmaceutically acceptable salt, ester, amide.