Journal ArticleDOI
Organolanthanide-Catalyzed Hydroamination. A Kinetic, Mechanistic, and Diastereoselectivity Study of the Cyclization of N-Unprotected Amino Olefins
TLDR
In this article, an efficient, regiospecific Cp{sup {prime}}{sub 2}LnR (Cp{Sup {prime} = {eta}{sup 5}-Me{sub 5}C{sub 3}H{sub 4]NCHR{sup 1}R{sup 2}CH=CH{sub 1}Abstract:
This contribution reports the efficient, regiospecific Cp{sup {prime}}{sub 2}LnR (Cp{sup {prime}} = {eta}{sup 5}-Me{sub 5}C{sub 5};R = H, CH(TMS){sub 2}, {eta}{sup 3}-C{sub 3}H{sub 5}, N(TMS){sub 2}; Ln-La,Nd,Sm,Y,Lu)-catalyzed hydroamination/cyclization of the amino olefins H{sub 2}NCHR{sup 1}R{sup 2}CH=CH{sub 2} to yield heterocycles. Kinetic isotope effects are observed for some of the cyclizations. The complexes were synthesized to model species in the catalytic cycle. Two independent molecules crystallize per unit cell with average La-NHCH{sub 3} and La{le}NH{sub 2}CH{sub 3} bond distances of 2.31 (1) and 2.70 (1) {Angstrom}, respectively. The amine-amido complexes undergo rapid intramolecular proton transfer between some of the amine and amido ligands. Intermolecular exchange with free amine is rapid on the NMR time scale at -80 {degrees}C. The ordering of precatalyst activities accords with known olefin insertion reactivities. Diastereoselection in H{sub 2}NCH(CH{sub 3})(CH{sub 2}){sub 2}CH=CH{sub 2}(5) cyclization depends on both lanthanide and ancillary ligation. Mechanistic evidence suggests that olefin insertion into the Ln-N bond of the amine-amido complexes is turnover-limiting and is followed by a rapid protonolysis of the resulting Ln-C bond. The proposed catalytic mechanism invokes parallel manifolds, with one manifold populated at high amine concentrations exhibiting high diastereoselectivity in the cyclization of 5, and with the second, favoredmore » at low substrate concentrations, exhibiting lower diastereoselectivity. The catalyst at high amine concentrations is postulated to be a Ln(amido)(amine){sub 2} complex. 93 refs., 15 figs., 8 tabs.« lessread more
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Journal ArticleDOI
Hydroamination: direct addition of amines to alkenes and alkynes.
TL;DR: Hydroamination of Alkenes and Alkynes under Microwave Irradiation and Nitromercuration Reactions 3878 9.8.4.5.
Journal ArticleDOI
Transition-metal-catalyzed addition of heteroatom-hydrogen bonds to alkynes.
Journal ArticleDOI
Transition-Metal-Catalyzed Reactions in Heterocyclic Synthesis
Journal ArticleDOI
Metal-Initiated Amination of Alkenes and Alkynes.
Thomas Müller,Matthias Beller +1 more
TL;DR: The catalytic production of organic molecules is one of the most important applications of organometallic chemistry and enantioselective syntheses of molecules bearing an amine functionality use classical stoichiometric reactions with chiral auxiliaries or utilize enantiomerically pure starting material.
Journal ArticleDOI
Organolanthanide-catalyzed hydroamination.
Sukwon Hong,Tobin J. Marks +1 more
TL;DR: Sterically less encumbered ligand designs have been developed to improve reaction rates, and metallocene and nonmetallocene chiral lanthanide complexes have been synthesized for enantioselective hydroamination.