Titanium Catalysts with Linked Indenyl–Amido Ligands for Hydroamination and Hydroaminoalkylation Reactions

Abstract

Titanium complexes containing a bridging indenylethylamido ligand have been synthesized and used as catalysts for hydroamination and hydroaminoalkylation reactions. All dichloro titanium complexes (η 5 :η 1 -Ind-C 2 H 4 -NR)TiCl 2 (R = i-Pr (2a), t-Bu (2b), Cy (2c), Ph (2d)), which were prepared by reacting TiCl 4 (Et 2 O) 2 with Li 2 [Ind-C 2 H 4 -NR], were fully characterized by single-crystal X-ray analysis. Reaction of 2a−c with methyllithium gave the thermally sensitive corresponding dimethyl titanium complexes [η 5 :η 1 -Ind-C 2 H 4 -N(alkyl)]TiMe 2 (alkyl = i-Pr (3a), t-Bu (3b), Cy (3c)), while the N-aryl-substituted dimethyl titanium complexes [η 5 :η 1 -Ind-C 2 H 4 -N(aryl)]-TiMe 2 (aryl = Ph (3d), p-MeOC 6 H 4 (3e)) were directly prepared by reacting Li 2 [Ind-C 2 H 4 -N(aryl)] with in situ generated Cl 2 TiMe 2 . In the case of complex 3d, the molecular structure could be determined by single-crystal X-ray analysis. All dimethyl titanium complexes (η 5 :η 1 -Ind-C 2 H 4 -NR)TiMe 2 (R = i-Pr (3a), t-Bu (3b), Cy (3c), Ph (3d), p-MeOC 6 H 4 (3e)) were finally used as precatalysts for the intermolecular hydroaminoalkylation of 1-octene (4), the intramolecular hydroamination and hydroaminoalkylation reactions of aminoalkenes, and the intermolecular hydroamination of 1-phenylpropyne (12). These experiments showed that the N substituent of the indenylethylamido ligand strongly influences the activity of the catalysts in the individual reactions.

Reaction of Pentafulvene Titanium and Zirconium Complexes with Phosphorus Ylides: Stoichiometric Reactions and Catalytic Intramolecular Proton Shuttles

“…Compounds Ti2a−e were characterized by NMR spectroscopy. Table 1 summarizes selected 1 H, 13 C, and 31 P NMR data compared to a selection of the used free ylides.…”

“…Characteristic of all compounds are the 1 H and 13 C NMR shifts of the α-CH ylide group connected to the metal center. Those are significantly shifted to lower fields, compared to the free ylides, and are in good comparison to known complexes.…”

“…Reacting the pentafulvene (Zr1a, Zr1b) and benzofulvene complexes (Zr1a-benzo, Zr1b-benzo) with the ylides Y1 and Y2 under mild conditions, the compounds Zr2a−Zr2c can be isolated as yellow solids in moderate to good yields. Compounds Zr2a−c were characterized by NMR spectroscopy (Zr2a-benzo is insoluble in common deuterated solvents); Table 2 summarizes selected 1 H, 13 C, and 31 P NMR data. Similar to the complexes Ti2a−e, the characteristic NMR shifts of the CH exo 31,36,31 and CH ylide group can be observed.…”

Tandem Hydroamination/Cyclization Access to N-2(5H)-Furanone Derivatives for COX-2 Inhibitor

“…Hence, it is more and more desirable to achieve the N -2­(5 H )-furanone derivatives efficiently by a noble metal-free catalyst. That is, the active centers of the catalyst are directly influenced by amine substrate (i) . Alkynes, with a too-high reactivity bearing electron-donating groups, obtains some side effects such as self-polymerization (ii) .…”

“…That is, the active centers of the catalyst are directly influenced by amine substrate (i). 14 Alkynes, with a too-high reactivity bearing electron-donating groups, obtains some side effects such as self-polymerization (ii). 15 As for a major shortcoming, it is required of directing groups to build selective C−H activation with the existence of multiple C−H bonds (iii).…”