The 1Hmr and 13Cmr spectra for 15 4-alkylidene-1-pyrazolines and 19 alkylidenecyclopropanes are reported. The assignments of E and Z isomers are made on the basis of shielding effects about the exo cyclic double bonds. The addition of diazomethane-d2 to 1,2-butadiene is shown to be both regiospecific and stereospecific.

Es werden die Spektren von Pyrazolinen wie z.B. (I) untersucht, die durch Cycloaddition von Diazoalkanen an die entsprechenden Diene dargestellt werden.