402937-77-3Relevant academic research and scientific papers
Hydroamination of Alkynes Catalyzed by Imido Complexes of Titanium and Vanadium
Lorber, Christian,Choukroun, Robert,Vendier, Laure
, p. 1845 - 1850 (2004)
Intermolecular alkyne hydroamination with primary amines is catalyzed with group 5 (vanadium and tantalum) transition metal complexes and a new imido-Ti(IV) complex. The reaction is very regioselective. The scope of the reaction was investigated with a variety of alkynes and amines; 1-hexyne and anilines were found to be especially good substrates.
Catalytic formal [2+2+1] synthesis of pyrroles from alkynes and diazenes via TiII/TiIV redox catalysis
Gilbert, Zachary W.,Hue, Ryan J.,Tonks, Ian A.
, p. 63 - 68 (2015/12/30)
Pyrroles are structurally important heterocycles. However, the synthesis of polysubstituted pyrroles is often challenging. Here, we report a multicomponent, Ti-catalysed formal [2+2+1] reaction of alkynes and diazenes for the oxidative synthesis of penta- and trisubstituted pyrroles: a nitrenoid analogue to classical Pauson-Khand-type syntheses of cyclopentenones. Given the scarcity of early transition-metal redox catalysis, preliminary mechanistic studies are presented. Initial stoichiometric and kinetic studies indicate that the mechanism of this reaction proceeds through a formally TiII/TiIV redox catalytic cycle, in which an azatitanacyclobutene intermediate, resulting from [2+2] alkyne + Ti imido coupling, undergoes a second alkyne insertion followed by reductive elimination to yield pyrrole and a TiII species. The key component for catalytic turnover is the reoxidation of the TiII species to a TiIV imido via the disproportionation of an η2-diazene-TiII complex.
A general and facile one-step synthesis of imido-titanium(IV) complexes: Application to the synthesis of compounds containing functionalized or chiral imido ligands and bimetallic diimido architectures
Lorber, Christian,Choukroun, Robert,Vendier, Laure
, p. 4503 - 4518 (2007/10/03)
One-pot reactions of Ti(NMe2)4 with a wide range of primary alkyl, aryl, and silylamines RNH2 in the presence of excess chlorotrimethylsilane produced the corresponding imido-titanium(IV) complexes [Ti(=NR)Cl2(NHMe2)2] (1a-j), in which R = tBu, 1-adamantane, Ph3C, Ph3Si, Ph, 2,6-iPr2-C 6H3, 2,6-Cl2-C6H3, 2,6-Br2-4-Me-C6H2, C6F5, and 3,5-(F3C)2-C6H3. This general synthesis, which starts from commercially available reagents, represents a simple and direct route to imido complexes. Reaction of complexes 1 with pyridine afforded the six-coordinate tris-pyridine adducts [Ti(=NR)Cl 2(Py)3] (2). Another advantage of this method is its tolerance to other functional groups; complexes that contain halides, ether, dialkylamino, cyano, ethynyl, olefin, and nitro substituents on the imido moiety have been prepared. The use of enantiomerically pure primary amines affords the first group of titanium complexes that contain chiral imido groups, and the use of diamines produces diimido complexes. Alternatively, CH3I has been used as an alkylating agent to generate titanium-imido complexes of the type [Ti(NR)I2(THF)2]2. All compounds were fully characterized by spectroscopic methods (IR, 1H NMR, 13C NMR) and elemental analysis. Some of the compounds were also analyzed by single-crystal X-ray diffraction studies. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
