Development of the Ti-Catalyzed Intermolecular Hydroamination of Alkynes

Abstract

This account describes the development of Ti-catalyzed intermolecular hydroamination reactions of alkynes, achieved in the author's laboratories during the last five years. Starting from initial ideas and early results with Cp 2 TiMe 2 as a catalyst precursor, mechanistic studies and applications of Cp 2 TiMe 2 -catalyzed hydroaminations of alkynes for the synthesis of biologically interesting classes of compounds are presented. Particular attention is paid to the identification of improved second generation catalysts such as Cp* 2 TiMe 2 and Ind 2 TiMe 2 . 1

Ligand Bridged and Bis‐ligand Coordinated Titanium Complexes: Synthesis, Structure and Relevance to Phenylacetylene Hydroanilination Catalysis

“…Traditionally, the hydroamination reaction catalyzed by titanium catalyst should be carried out by 10 mol% of catalyst loading, 5,6 however, our study indicated that the catalyst loading could be reduced to 5 mol% by using the binuclear complex 1 as the catalyst. It was proposed that both titanium centers be involved in the hydroanilination reactions.…”

“…[1][2][3] Compared to the widely used catalysts, such as late transition metal and lanthanide complexes, titanium catalysts have significant advantages over toxic mercury and more expensive ruthenium, palladium, rhodium and gold ones. Of all the titanium hydroamination catalysts, the most efficient ones for such transformation include titanium dialkyl, [4][5][6] titanium diamide 7,8 and titanium imide 9,10 complexes. The support ligands, usually chelating to the titanium centers, are cyclopentadienyl, [4][5][6] …”

“…Of all the titanium hydroamination catalysts, the most efficient ones for such transformation include titanium dialkyl, [4][5][6] titanium diamide 7,8 and titanium imide 9,10 complexes. The support ligands, usually chelating to the titanium centers, are cyclopentadienyl, [4][5][6] …”

Asymmetric Hydroamination

“…Group 4 metal-based catalysts have been studied intensively in hydroamination reactions involving alkynes and allenes [77][78][79][80][81], but (achiral) hydroamination reactions involving aminoalkenes were only recently reported [82][83][84]. The reactivity of these catalysts is significantly lower than that of rare earth, alkali, and alkaline earth metal-based catalysts.…”

A Practical and Benign Synthesis of Primary Amines through Ruthenium‐Catalyzed Reduction of Nitriles

“…[2] In this respect, several interesting methods have been developed, such as the palladium-catalyzed amination of aryl halides, [3] hydro-A C H T U N G T R E N N U N G amination of olefins and alkynes, [4] hydroaminomethylation of olefins, [5] and reductive amination of carbonyl compounds. [6] In addition, the catalytic hydrogenation of nitriles represents an atom-economic and valuable route to amines.…”