The reaction of 3-methoxy cinnamoyl chloride (1 mol) with diazo-n-octane (2 mol and 3 mol) gives 1-diazo-1-n-heptyl-4-(3-methoxy) phenyl but 3-ene 2-one and 4-(3-methoxy) phenyl-3-n-heptyl 1-diazoacetyl-5-n-heptyl pyrazoline. The diazoketones were characterised by various physico-chemical techniques.