4 r 5 r 6 and r 7 independently represent hydrogen lower c 1 c 4 alkyl lower perhaloalkyl c 1 c 4 cyano hydroxyl nitro lower alkoxycarbonyl halogen lower c 1 c 4 alkoxy lower perhaloalkoxy c 1 c 4 amino or lower alkyl c 1 c 4 amino to give a compound of formula i wherein ar r 1 r 2 r 3 r 4 r 5 r 6 r 7 and x are the same as defined earlier the condensation of the compound of formula ii with a compound of formula iii to give a compound of formula i is carried out in the presence of a condensing agent which is selected from the group consisting of 1 3 dimethylaminopropyl 3 ethyl carbodiimide hydrochloride edc and 1 8 diazabicyclo 5 4 0 undec 7 ene dbu the condensation of the compound of formula ii with a compound of formula iii to give a compound of formula i is carried out in a suitable solvent selected from the group consisting of n n dimethylformamide and dimethylsulphoxide the reaction temperature and duration may be adjusted according to the desired needs alternatively the compounds of the present invention can be prepared by modified mannich reaction of an acetylenic compound with an aldehyde and substituted azabicyclo 3 1 0 cyclohexane derivatives the compounds of the invention can also be synthesised through ester alcohol interchange involving 4 amino 2 butynyl alcohols and various alkyl esters or treatment of amino butynols with various acid chlorides or transesterification reactions suitable salts of the compounds represented by the formula i were prepared so.