Phosphine-catalyzed [5+1] annulation of β'-acetoxy allenoates: straightforward access to tetrahydroquinoline derivatives.

An unprecedented phosphine-catalyzed [5+1] annulation of β'-acetoxy allenoates with 1,5-dinucleophiles has been developed, which provides novel and facile access to functionalized tetrahydroquinolines in good to high yields in the presence of PPh 3 and K 3 PO 4 under mild reaction conditions. Notably, it is the first report of β'-acetoxy allenoates acting as C1 synthons in Lewis base-catalyzed annulation reactions.