Synthesis and Structure of Sterically Congested, New Alkenes, syn- and anti-9,9′-Bibenzonorbornenylidenes

Sterically congested alkenes, syn- and anti-9,9′-bibenzonorbornenylidenes (1a) and (1b), were synthesized starting from 9-benzonorbornenone in good overall yields and were isolated in pure form. Their structures were elucidated by analyses of NMR spectra and established by X-ray crystallographic analysis. Structures of the two episulfides, which served as precursors leading to 1a and 1b, were also determined by X-ray crystallographic analysis.

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