Nucleophilic Reactivities of Azulene and Fulvenes

European Journal of Organic Chemistray, 2009, 2009, 8, 1202-06 published on 16.01.2009
European Journal of Organic Chemistry, online article
The kinetics of the reactions of azulene (1), 6,6-dimethylfulvene (2), 6-[4-(dimethylamino)phenyl]fulvene (3) and 6-(julolidin-9-yl)fulvene (4) with a set of benzhydrylium ions (reference electrophiles) have been investigated in MeCN. The second-order rate constants for these reactions correlate linearly with the electrophilicity parameters (E) of the benzhydrylium ions. According to the linear free-enthalpy relationship log k2(20 °C) = s(N + E), the nucleophilicity parameters N and s of the -nucleophiles 1-4 were determined and compared with those of other types of nucleophiles. Azulene (1, N = 6.66) is about 10 times more nucleophilic than N-methylpyrrole and comparable to 2-methylindole.
TU München