Ligand-dependent stereoselective Suzuki-Miyaura cross-coupling reactions of ß-enamido triflates.

The stereoselective Suzuki-Miyaura cross-coupling of (Z)-ß-enamido triflates is demonstrated. Depending on the nature of the ligand in the palladium catalyst, either retention or inversion of the configuration during the synthesis of ß,ß-diaryl-substituted enamides is observed. Thus, the method provides synthetic access to both isomers of the target enamides from (Z)-ß-enamido triflates.

Stereoselective Synthesis of (Z)-ß-Enamido Triflates and Fluorosulfonates from N-Fluoroalkylated Triazoles.

N-Fluoroalkylated 1,2,3-triazoles in the presence of triflic acid or fluorosulfonic acid underwent a cascade reaction consisting of triazole protonation, ring opening, nitrogen elimination, sulfonate addition, HF elimination, and hydrolysis to furnish novel trifluoromethanesulfonyloxy- or fluorosulfonyloxy-substituted enamides, respectively, in a highly stereoselective fashion. The vinyl triflates underwent cross-coupling reactions to a variety of substituted enamides and serve as sources of the aminovinyl cations. In reactions with triflic acid, electron-rich triazoles afforded 2-fluoroalkylated oxazoles.

Synthesis of tetrafluoroethylene- and tetrafluoroethyl-containing azides and their 1,3-dipolar cycloaddition as synthetic application.

Tetrafluoroethylene-containing azides are accessed in two steps (one pot) from tetrafluoroalkyl bromides by metalation and reaction with electrophilic azides. Subsequent copper(i)-catalyzed azide-alkyne cycloaddition afforded N-tetrafluoroethyl and N-tetrafluoroethylene 4-substituted 1,2,3-triazoles. In addition, the protocol for the synthesis of 4,5-disubstituted 1,2,3-triazoles is presented.

Azidoperfluoroalkanes: Synthesis and Application in Copper(I)-Catalyzed Azide-Alkyne Cycloaddition.

We report an efficient and scalable synthesis of azidotrifluoromethane (CF3 N3 ) and longer perfluorocarbon-chain analogues (RF N3 ; RF =C2 F5 , n C3 F7 , n C8 F17 ), which enables the direct insertion of CF3 and perfluoroalkyl groups into triazole ring systems. The azidoperfluoroalkanes show good reactivity with terminal alkynes in copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC), giving access to rare and stable N-perfluoroalkyl triazoles. Azidoperfluoroalkanes are thermally stable and the efficiency of their preparation should be attractive for discovery programs.

Modular Approach to Heterogenous Catalysis. Manipulation of Cross-Coupling Catalyst Activity.

A new type of robust, heterogeneous, modular Pd catalyst with metal embedded in the gel matrix is presented. The regulatory element of its catalytic activity has been introduced via chemical changes in the gel. The concept is illustrated in a series of Suzuki-Miyaura cross-coupling reactions. The demonstrated catalyst activity variations depend on the structure of the gel.

Metallothionein-inspired prototype of molecular pincer.

Study of Zn and Pb release from complexes with natural and synthetic amidothiol motifs inspired the design of a "molecular pincer" that scavenges quantitatively metals from liquid environment and releases them, on-demand, under very mild oxidative conditions.

Copper/ascorbic acid dyad as a catalytic system for selective aerobic oxidation of amines.

A new, environmentally benign system based on an ascorbic acid (vitamin C)/copper dyad is presented, which facilitates the oxidation of amines to carbonyl compounds. The oxidation utilizes aerobic oxygen as the ultimate electron scavenger, which accepts electrons in a cascade-like fashion via a Cu(+)/Cu(2+) and ascorbic/dehydroascorbic acid couple. Dehydroascorbic acid, the oxidation agent, finally oxidizes amine substrates in a selective fashion after forming a Schiff base intermediate. The selectivity as well as generality of the method is demonstrated on various substrates.