A new route to 3-(2-vinylphenyl)-2-methyl-2H-isoquinolin-1-ones and benzo[c]phenanthridines: total synthesis of fagaronine

Treatment of N-carbethoxy-1-benzylideneisoquinolines with LDA gives N-ethoxycarbonyl-1-amino-1-(2-vinylphenyl)-2-phenylethylenes, which can be transformed into 3-(2-vinylphenyl)-2-methyl-2H-isoquinolin-1-ones by Bischler–Napieralski reactions, and thence into benzo[c]phenanthridin-6-ones. The use of this route for a new total synthesis of fagaronine is described.