A study on the solid-solid phase transitions of (E)- and (Z)-9-(bicyclo[4.2.1]nonan-9-ylidene)bicyclo[4.2.1]nonane and some related compounds. Assignment of the configuration to the product of monoepoxidation of (E)-9-(bicyclo[4.2.1]non-3-en-9-ylidene)bicyclo[4.2.1]non-3-ene by ¹H nuclear magnetic resonance spectroscopy using the shift reagent Eu(fod) <inf>3</inf>

The solid-solid phase transitions of (E)- and (Z)-9-(bicyclo[4.2.1]non-3- en-9-ylidene)bicyclo[4.2.1]non-3-ene (1) and (2), (E)- and (Z)-9-(bicyclo[4.2.1] nonan-9-ylidene)bicyclo[4.2.1]nonane (3) and (4), (1R,1″R,6S,6″S,9r, 9″r)- and (1R,1″R,6S,6″S,9r,9″s)-dispiro(bicyclo[4.2.1] nonane-9,2′-oxirane-3′,9″-bicyclo[4.2.1]nonane) (5a) and (6), and (1R,1″R,6S,6″S, 9s,9″s)- and (1R,1″R,6S,6″S, 9r,9″s)-dispiro(bicyclo[4.2.1]non-3-ene-9,2′-oxirane-3′, 9″-bicyclo[4.2.1]non-3″-ene) (7a) and (8) are studied by differential scanning calorimetry. In general, the syn-compounds, (1), (3), (5a), and (7a) show higher m.p.s and exhibit plasticity over a larger range of temperatures than anti-compounds (2), (4), (6), and (8). The intracyclic double bond is a negative factor for plasticity in these compounds. The unit-cell dimensions of alkene (4) and epoxide (7a) have been determined by X-ray diffraction. The configuration of epoxide (7a) has been established through the comparison of its 200 MHz 1H n.m.r. spectrum with those of the epoxide (8) and the model compounds syn- (9) and anti-bicyclo[4.2.1]non-3-en-9- ol (10). Also, the assigned configuration of epoxide (7a) has been confirmed through the analysis of its 1H n.m.r. spectrum in the presence of known amounts of the shift reagent Eu(fod)3.