Synthesis of chiral (tetrazolyl)methyl-containing acrylates via silicon-induced organocatalytic kinetic resolution of Morita-Baylis-Hillman fluorides.

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.

Enantioselective Trichloromethylation of MBH-Fluorides with Chloroform Based on Silicon-assisted C-F Activation and Carbanion Exchange Induced by a Ruppert-Prakash Reagent.

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 in 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.

Asymmetric Mannich reaction between (S)-N-(tert-butanesulfinyl)-3,3,3-trifluoroacetaldimine and malonic acid derivatives. Stereodivergent synthesis of (R)- and (S)-3-amino-4,4,4-trifluorobutanoic acids.

Inorganic as well as organic base catalysis was found to be effective for diastereoselective Mannich additions of malonic acid derivatives to (SS)-N-(tert-butanesulfinyl)-3,3,3-trifluoroacetaldimine. In the presence of catalytic amounts of inorganic bases, n-BuLi or DMAP, the reaction gives the corresponding (R,SS)-ß-aminomalonates in good yield and with diastereoselectivity up to 9/1 dr. In contrast, phosphazene bases favour the formation of the (S,SS)-diastereomer with selectivities as high as 99/1. Simple choosing of an appropriate base catalyst for the Mannich addition reaction allowed us to obtain enantiomerically pure (R)- or (S)-configured 3-amino-4,4,4-trifluorobutanoic acids after hydrolysis and decarboxylation of the corresponding ß-aminomalonates.

Kinetic resolution of allyl fluorides by enantioselective allylic trifluoromethylation based on silicon-assisted C-F bond cleavage.

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.

Organic base-catalyzed stereodivergent synthesis of (R)- and (S)-3-amino-4,4,4-trifluorobutanoic acids.

Organic base-catalyzed reaction of (S)-N-tert-butanesulfinyl (3,3,3)-trifluoroacetaldimine with dialkyl malonates was found to be effective for synthesis of both (S,S(S)) and (R,S(S)) ß-aminomalonates in high yield with good to excellent diastereoselectivity (76-98% de). The products of this Mannich reaction provide direct access to ß-trifluoromethyl-ß-alanine of either (R) or (S) absolute configuration.

Organocatalyzed regio- and enantioselective allylic trifluoromethylation of Morita-Baylis-Hillman adducts using Ruppert-Prakash reagent.

The organocatalyzed regioselective allylic trifluoromethylation of Morita-Baylis-Hillman adducts using Ruppert-Prakash reagent was achieved in high to excellent yields via a successive S(N)2'/S(N)2' mode for the first time. The reaction was extended to the asymmetric allylic trifluoromethylation by the use of a bis-cinchona alkaloid catalyst with high enantioselectivities up to 94% ee.