The derivatives of trans-bicyclo[3.3.0]octane 3 and 6 have been obtain
ed the bicyclo[3.3.0]oct-1-enes, sterically hindered at the exo-side,
via photoinduced [2+2]cycloaddition of 1 with ethylvinyl ether and by
hydroboration-oxidation of 5d, respectively.