Palladium Pincer-Complex Catalyzed Allylation of Tosylimines by Potassium Trifluoro(allyl)borates

Amine adducts of triallylborane as highly reactive allylborating agents for Cu(I)-catalyzed allylation of chiral sulfinylimines

The implementation of selective catalytic processes with highly active reagents is an attractive strategy that meets the modern principles of sustainable development of chemistry. In the current study, we for the first time describe the method and general principles of Cu(I)-catalyzed allylation of imines with amine adducts of allylic triorganoboranes. Triallylborane is an extremely reactive compound and cannot be used for the catalytic allylation of imines, whereas its amine adducts are ideal substrates for catalysis. The structure of the amine fragment successfully balances the safety, selectivity and stability of the allylboron reagent, allowing it to demonstrate high activity in catalytic allylation reactions, exceeding many times any known allylboranes. The obtained results are supported by quantitative kinetics data and DFT calculations. The catalytic efficacy of the system was demonstrated on model sulfinylimines (23 examples). High diastereoselectivity up to >99% was achieved, including for the gram-scale synthesis of 2-hydroxyphenyl-derivatives. Taking into account the high reactivity and unsurpassed atom-economy of amine adducts of triallylborane (AAT), they can be considered as prospective allylation reagents with Cu(I) and other appropriate metallocatalysts.

Iron(III)-Catalyzed Synthesis of 2-Alkyl Homoallyl Sulfonyl Amides: Antiproliferative Study and Reactivity Scope of Aza-Prins Cyclization

A direct, catalytic, and complementary method to obtain 2-substituted homoallyl sulfonyl amides is described, starting from sulfonyl amides, aldehydes, and allyltrimethylsilane using iron(III) chloride as a sustainable catalyst. The scope of the process and the reactivity in aza-Prins cyclization is evaluated and supported by density functional theory (DFT) studies. Finally, an evaluation of the antiproliferative activity for this family of sulfonyl amides is also included.

Iron-Catalyzed Stereoselective Allylboration of 3,4-Dihydroisoquinolines with Potassium Allyltrifluoroborates

An iron-catalyzed allyation of isoquinoline with potassium allyltrifluoroborate is described. The operation of this reaction is very simple and highly practical. The diastereoisomer having two adjacent chiral centers were obtained in single anti-configuration.

Development of (quinolinyl)amido-based pincer palladium complexes: a robust and phosphine-free catalyst system for C–H arylation of benzothiazoles

Well-defined (quinolinyl)amido-pincer palladium complexes are developed and employed for the catalytic C–H bond arylation of benzothiazoles with aryl iodides, which can be recycled and reused for several cycles.

Asymmetric palladium-catalyzed umpolung cyclization of allylic acetate-aldehyde using formate as a reductant

Asymmetic palladium/chiral diphosphine-catalyzed umpolung cyclization of allylic acetate-aldehyde using formate as a reductant affordscis-disubstituted pyrrolidine, tetrahydrofuran, and spiro carbocycle.

Palladacycles: Effective Catalysts for a Multicomponent Reaction with Allylpalladium(II)-Intermediates

Palladium(II) complexes with an auxiliary bidentate ligand featuring one C-Pd bond and a Pd-N-donor bond (palladacycles) have been shown to afford improved yields of homoallylic amines from a three-component coupling of boronic acids, allenes and imines in comparison to the yields of homoallylic amines achieved with the originally reported catalyst (Pd(OAc)₂/P(t-Bu)₃), thus extending the scope of the reaction. ³¹P NMR monitoring studies indicate that distinct intermediates featuring Pd-P bonds originate in the reactions catalyzed by either Pd(OAc)₂/P(t-Bu)₃ or the pallada(II)cycle/P(t-Bu)₃ systems, suggesting that the role of the pallada(II)cycles is more complex than just precatalysts. The importance of an additional phosphine ligand in the reactions catalyzed the pallada(II)cycles was established, and its role in the catalytic cycle has been proposed. Insights into the nature of the reactive intermediates that limit the performance of the originally reported catalytic systems has been gained.

Iron-catalyzed 1,4-hydroboration of 1,3-dienes

A chemo-, regio-, and stereoselective iron-catalyzed 1,4-hydroboration of dienes that affords gamma-disubstituted allylboranes has been developed. 1,4-Hydroboration of 2-substituted dienes forms allylborane products with (E)-trisubstituted double bonds exclusively.

Allylic ethers as educts for Suzuki-Miyaura couplings in water at room temperature

The first examples of Suzuki-Miyaura couplings of allylic ethers are reported. These can be done not only under very mild room-temperature conditions but also in water as the only medium. The process is made possible by micellar catalysis using the designer surfactant PTS.

Catalytic performance of symmetrical and unsymmetrical sulfur-containing pincer complexes: synthesis and tandem catalytic activity of the first PCS-pincer palladium complex

The synthesis and catalytic applications of a new aryl-based unsymmetrical PCS-pincer complex are reported. Preparation of the robust air- and moisture-stable PCS-pincer palladium complex 5[X] started from the symmetrical alpha,alpha'-dibromo-meta-xylene and involved the selective substitution of one bromide by PPh(2)(BH(3)), followed by substitution of the second bromide by SPh and subsequent introduction of the palladium. The new PCS complexes (5[X]) were employed as catalysts in two important organic transformations. Firstly, complex 5[Cl] displays high catalytic activity in aldol reactions but enters the catalytic cycle as a precatalyst. Secondly, complex 5[BF(4)] displays tandem catalytic activity in the coupling of allyl chlorides with aldehydes and imines in the presence of hexamethylditin. In these tandem catalytic reactions the first process is the conversion of allyl chlorides into trimethylallyltin (and trimethyltin chloride) with Sn(2)Me(6), which is followed by catalytic allylation of aldehyde and sulfonimine substrates. In addition, we present a new catalytic process for the one-pot allylation of 4-nitrobenzaldehyde with vinyloxirane. The catalytic performance of the novel PCS-pincer palladium complex was compared to those of its symmetrical PCP- and SCS-pincer complex analogues. It was concluded that the unsymmetrical PCS complex advantageously unifies the attractive catalytic features of the corresponding symmetrical pincer complexes including both (pi-) electron-withdrawing (such as phosphorus) or (sigma-) electron-donating (such as sulfur and nitrogen) heteroatoms. Thus, in the aldol reaction the PCS-pincer palladium complex 5[X] provides a high turnover frequency, while in the tandem process both reactions are catalysed with sufficiently high activity.