Coumarins from Free ortho-Hydroxy Cinnamates by Heck-Matsuda Arylations: A Scalable Total Synthesis of (R)-Tolterodine

Free ortho-hydroxy cinnamate ester derivatives are evaluated in the synthesis of structurally diverse 4-aryl-coumarins via a tandem Heck-Matsuda cyclization reaction. Free phenolic groups were considered incompatible with such a reaction, which usually provide the corresponding diazo dyes. A concise and scalable route employing a ligand-free, Pd-catalyzed Heck-Matsuda arylation under aerobic conditions for the preparation of (R)-Tolterodine in high overall yield and ee is also presented.