Homoleptic Lanthanide Amides as Homogeneous Catalysts for Alkyne Hydroamination and the Tishchenko Reaction

Abstract

The homoleptic bis(trimethylsilyl)amides of Group 3 metals and lanthanides of the general type [Ln[N(SiMe3)2]3] (1) (Ln=Y, lanthanide) represent a new class of Tishchenko precatalysts and, to a limited extent, precatalysts for the hydroamination/cyclization of aminoalkynes. It is shown that 1 is the most active catalyst for the Tishchenko reaction. This contribution presents investigations on the scope of the reaction, substrate selectivity, lanthanide-ion size-effect, and kinetic/mechanistic aspects of the Tishchenko reaction catalyzed by 1. The turnover frequency is increased by the use of large-center metals and electron-withdrawing substrates. The reaction rate is second order with respect to the substrate. While donor atoms, such as nitrogen, oxygen, or sulfur, on the substrate decrease the turnover frequency, 1 shows a tolerance for a large number of functional groups. For the hydroamination/cyclization of aminoalkynes, 1 is less active than the well-known metallocene catalysts. On the other hand, 1 is much more readily accessible (one-step synthesis or commercially available), than the metallocenes and might therefore be an attractive alternative catalyst.

Synthesis, characterization of amine-bridged bis(phenolate) yttrium alkyl complex and its catalytic behavior for the Tishchenko reaction

“…However, it took several days to complete the reaction, and the catalysts are expensive and difficult to prepare. Berberich and Roesky [12] , and Bürgstein et al [13] found that lanthanide silylamides Ln[N(SiMe 3 ) 2 ] 3 are among the best catalyst precursors for this reaction, and the reaction can be …”

Lanthanide‐Catalyst‐Mediated Tandem Double Intramolecular Hydroalkoxylation/Cyclization of Dialkynyl Dialcohols: Scope and Mechanism

“…Successful intermolecular transformations include ynone synthesis,23 cross‐aldol reactions,24 coupling of isocyanides with terminal alkynes,25 dimerization of terminal alkynes,26 guanylation of amines,27 hydrosilylation,28 hydroboration,29 Tishchenko aldehyde dimerization,30and amidations 31. Intramolecular transformations include hydroelementation processes, such as hydroamination,32, 30b hydrophosphination,20b and hydroalkoxylation 33. In regard to organolanthanide‐mediated tandem hydrofunctionalization processes, several very efficient and selective hydroamination/CC bond formation sequences have been reported [e.g., Eq.…”

Synthesis and molecular structures of lanthanocene amide complexes and their catalytic activity for addition of amines to nitriles

“…For example, lanthanide amides are active catalysts for a variety of olefin and alkyne transformations, including hydroamination/cyclization [1,2], hydroalkoxylation/cyclization [3], ethylene polymerization [4,5], hydrosilylation [6], the addition of terminal alkynes to nitriles [7], the monocoupling reaction of isocyanides with terminal alkynes [8]. They are also found to be the catalysts for the polymerization of polar monomers, such as methylmethacrylate [9][10][11], phenylisocyanate [12], e-caprolactone and lactide [13,14], as well as for the Tishchenko reaction [15,16], guanylation of amines with carbodiimides [14], amidation of aldehydes with amines [17], and Mannich-type reaction [18]. etc.…”