Pd-Catalyzed Regio- and Stereoselective Cyclization−Heck Reaction of Monoesters of 1,2-Allenyl Phosphonic Acids with Alkenes

[reaction: see text] The cyclization-Heck reactions of monoesters of 1, 2-allenyl phosphonic acids with alkenes were studied. The reaction afforded 4-(1-Z-alkenyl)-2-ethoxy-2,5-dihydro[1,2]oxaphosphole 2-oxides regio- and stereoselectively. Pd(II) was regenerated from the in situ formed Pd(0) using CaH2(cat.)/NaI/O2 or benzoquinone to furnish the catalytic cycle.