Theoretical study on E-selective HWE reactions

Mechanistic investigation on the mechanism of the Horner-Wadsworth-Emmons (HWE) reaction of (MeO)₂P(O)CHLiCO₂Me with CH₃CHO using ab initio calculations （RHF/6-31+G*）. Oxaphosphetane formation is the rate-limiting step (TS2), in which the transition state leading to the E-olefin is more stable than that leading to the Z-isomer.^1,2

1) Ando, K. J. Org. Chem. 1999, 64, 6815-6821.

2) Ando, K. J. Org. Synth. Chem., Jpn. 2000, 58, 869-876. (written in Japanese)