Switchable Enantioselectivity in Conjugate Alkyne Addition of β,γ-Unsaturated α-Keto Esters by Asymmetric Binary Acid Catalysis

Switchable enantioselectivity was uncovered in the enantioselective catalytic conjugate addition of β,γ-unsaturated α-keto esters with terminal alkynes to the chiral Lewis acid complex of In(BF4)3 and chiral phosphoric acid.

Highly Enantioselective Chiral Diol-Catalyzed Conjugate Addition of Boronic Acids to α,β-Unsaturated Trifluoromethyl Ketones

The (R)-3,3'-(3,5-(CF3)2-C6H3)2-BINOL-catalyzed enantioselective conjugate addition of organic boronic acids to α,β-unsaturated 1,1,1-trifluoromethyl ketones affords corresponding addition products bearing a stereogenic center at the β-position in moderate to high yields and excellent enantioselectivities (up to 99% ee), without any 1,2-addition product formation. Moreover, this catalytic protocol features mild reaction conditions, a broad substrate scope, suitability for alkenylboronic acids and (hetero)arylboronic acids, and easy scale-up.

α,β-Disubstituted CF3-Enones as a Trifluoromethyl Building Block: Regioselective Preparation of Totally Substituted 3-CF3-Pyrazoles

An efficient pathway toward a novel class of trifluoromethyl building blocks was elaborated. The reaction of α-CF₃-enamines with arylaldehydes resulted in direct synthesis of α,β-diaryl-CF₃-enones isolated in up to 93% yield as E-isomers. The possible reaction mechanism was proposed using the Zimmerman-Traxler model. The reaction of α,β-diaryl-CF₃-enones with hydrazines opens a novel pathway to trifluoromethylated pyrazolines. Oxidation of pyrazolines with DDQ opened access to totally regioselective preparation of 3-CF₃-pyrazoles isolated in high yield. Using this strategy, 4-arylated derivatives of known drugs Celebrex, Mavacoxib, and SC-560 can be synthesized.

Synthesis of 1-(β-coumarinyl)-1-(β-indolyl)trifluoroethanols through regioselective Friedel-Crafts alkylation of indoles with β-(trifluoroacetyl)coumarins catalyzed by Sc(OTf)3

A highly efficient Friedel-Crafts alkylation of indole derivatives with β-(trifluoroacetyl)coumarins using Sc(OTf)3 as a catalyst has been developed, which gives regioselective 1,2-adducts to afford 1-(β-coumarinyl)-1-(β-indolyl)trifluoroethanols. A series of tertiary trifluoroethanols containing different indole and coumarin groups were synthesized in moderate to excellent yields (up to 95%) in the presence of 5 mol% catalyst in a short time (only 2 minutes at least). A mechanism of the reaction, in which the trace amount of water plays the role of proton transfer in catalyzing circulation was proposed and confirmed.

Recent Advances in Metal-Catalyzed Asymmetric 1,4-Conjugate Addition (ACA) of Nonorganometallic Nucleophiles

The metal-catalyzed asymmetric conjugate addition (ACA) reaction has emerged as a general and powerful approach for the construction of optically active compounds and is among the most significant and useful reactions in synthetic organic chemistry. In recent years, great progress has been made in this area with the use of various chiral metal complexes based on different chiral ligands. This review provides comprehensive and critical information on the enantioselective 1,4-conjugate addition of nonorganometallic (soft) nucleophiles and their importance in synthetic applications. The literature is covered from the last 10 years, and a number of examples from before 2007 are included as background information. The review is divided into multiple parts according to the type of nucleophile involved in the reaction (such as C-, B-, O-, N-, S-, P-, and Si-centered nucleophiles) and metal catalyst systems used.

Iridium-catalysed conjugated alkynylation of α,β-unsaturated amide through alkene isomerization

We have developed an iridium-catalysed conjugated alkynylation of α,β-unsaturated amide.

Copper-catalysed enantioselective Michael addition of malonic esters to β-trifluoromethyl-α,β-unsaturated imines

A diastereo- and enantioselective Michael addition of methyl malonate to β-trifluoromethyl unsaturated imines is presented.