ABSTRACT
Reported herein is a new approach for the asymmetric installation of a (tetrazolyl)methyl group via Si/F activation using organocatalytic kinetic resolution of racemic MBH-fluorides.
ABSTRACT
Enantioselective trichloromethylation of Morita-Baylis-Hillman (MBH)-type allylic fluorides with chloroform (HCCl3 ) under organocatalysis was achieved with high to excellent enantioselectivities. Silicon-assisted CF bond activation by a Ruppert-Prakash reagent and direct activation of HCCl3 by a carbanion exchange process with trifluoromethyl (CF3 ) carbanion generated inâ situ from the Ruppert-Prakash reagent realized the direct asymmetric trichloromethylation at a stereogenic allylic positon, without any help from transition metal catalysis, and under very mild conditions. Pre-activation of HCCl3 was not required. This method was extended to the direct enantioselective introduction of other C-H compounds such as alkyne, arene, indene, and FBSM without any pre-activation under a metal-free system.
ABSTRACT
Two birds, one stone! The first kinetic resolution of allyl fluorides was achieved by the development of an organocatalyzed enantioselective allylic trifluoromethylation. Two kinds of chiral fluorinated compounds, which incorporate C*F and C*CF3 units, respectively, can thus be accessed by a single transformation.