Patent ID: 7402707

Claim:
A method of preparation of a precursor oligocene compound comprising a cyclohexadienyl-group, the precursor oligocene having the formula in which: the cyclohexadienyl-group is optionally provided with a —C(O)-bridge between its 2 and 5 positions; R 3 , R 4 are the same as R 1 , R 2 or are H, alkyl, aryl, alkoxy, aryloxy or halogen R 5 , R 6 are H, C 1 -C 4 -alkyl, CN, C 1 -C 4 -alkoxy or halogen and may be the same or different; R 7 , R 8 , R 9 , R 10 are H, alkyl, aryl, halogen or alkoxy, and may be the same or different, and R 7 and R 8 , R 8 and R 9 , R 9 and R 10 may be in combination A 1 , A 2 , A 3 , A 4 , are H or an electron withdrawing group selected from the group consisting of Cl, Br, I, F, H, CN, OCH 3 , CF 3 , and may be the same or different, wherein the method comprises the acts of: a) reacting a dihydro-etheno-oligocene of the formula with a 1,1-disubstituted-cyolopentadiene of the formula to form a Diels-Alder adduct of the formula in which R 1 -R 6 and A 1 -A 4 are the same as above, and R 11 , R 12 is H, C 1 -C 8 -alkyl, aryl, aralkyl or alkaryl and R 1 and R 2 may be different or equal to each other, and may form together a ringshaped chain; and b) converting the adduct with an electrophilic or oxidizing agent to obtain the precursor oligocene compound.