A cationic gold(I)/PPh3 complex catalyzes cycloisomerizations of bicyclic N-alkenyl alkynylamides leading to tricyclic 2-pyridone derivs. at room temp. in good yields. The bicyclic N-alkenyl alkynylamides are readily prepd. starting from com. available 2-substituted cycloalkanones. E.g., reaction of 2-phenylcyclohexanone with 1-bromo-3-chloropropane, followed by NaN3, PPh3, and phenylpropiolic acid gave 45% bicyclic N-alkenyl alkynylamide I. Cycloisomerization of the latter in presence of AuCl(PPh3)3/AgBF4 gave 64% tricyclic 2-pyridone deriv. II. [on SciFinder(R)]
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