Treatment of beta-keto esters with terminal acetylenes in the presence of a catalytic amount of a manganese complex, MnBr(CO)(5), and molecular sieves, gave multisubstituted aromatic compounds in good to excellent yields. This reaction employs [2 + 2 + 2] cycloaddition of beta-keto esters and 2 equiv of terminal acetylenes with dehydration. In the case of a 1,3-diketone, the corresponding acetophenone derivative and its deacylated compound can be synthesized selectively.
Yoshikai, Naohiko; Zhang, Song-Lin; Yamagata, Ken-Ichi, Journal of the American Chemical Society, 2009, vol. 131, p. 4099 - 4109