Synthesis of 2H-1,2-oxaphosphorin 2-oxides via Ag2CO3-catalyzed cyclization of (Z)-2-alken-4-ynylphosphonic monoesters

Six new 2-ethoxy-2H-1,2-oxaphosphorin 2-oxides were synthesized with high regioselectivity in good yields via Ag2CO3-Catalyzed cyclization of (2)-2-alken-4-ynylphosphonic monoesters in CH2Cl2 at room temperature. This cyclization of P-OH to substituted alkynes is reported for the first time. The products are a class of phosphorus heterocycles with potential use and are heretofore prepared with difficulty.