Organolanthanide-catalyzed hydroamination. A kinetic, mechanistic, and diastereoselectivity study of the cyclization of N-unprotected amino olefins

Journal Article · Wed Jan 01 04:00:00 EST 1992 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja00027a036· OSTI ID:171659

Gagne, M R; Stern, C L; Marks, T J ^[1]

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1. Northwestern Univ., Evanston, IL (United States)

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, favored 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.

• Sponsoring Organization: USDOE
• OSTI ID: 171659
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 1 Vol. 114; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
CATALYTIC EFFECTS
CHEMICAL PREPARATION
CYCLIZATION
HETEROCYCLIC COMPOUNDS
ISOTOPE EFFECTS
LANTHANUM COMPLEXES
LUTETIUM COMPLEXES
NEODYMIUM COMPLEXES
RARE EARTHS
REACTION KINETICS
SAMARIUM COMPLEXES
YTTRIUM COMPLEXES