The formation of these quinolines can be easily followed by the variation of coloration of the reaction. Usually, the color of the mixtures containing Pd(II) species is yellow to dark red-brown for the common palladium-catalyzed reactions such as the Mizoroki−Heck reaction, the Suzuki−Miyaura cross-coupling reaction, the allylation reaction, or even the ene-type cyclization. 12 However, in the present ene-type reactions leading to the chiral ...
