Enantioselective synthesis of chiral phosphonylated 2,3-dihydrofurans by copper catalyzed asymmetric formal [3+2] cycloaddition of propargylic esters with β-keto phosphonates

Copper catalyzed asymmetric formal [3+2] cycloaddition of propargylic esters with β-keto phosphonates for the synthesis of chiral phosphonylated 2,3-dihydrofurans was developed. By using a bulky and structurally rigid tridentate ketamine P,N,N ligand, a series of optically active phosphonylated 2,3-dihydrofurans were prepared in high yields and up to 92% ee.