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)3

Abstract

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.