Organolanthanide-catalyzed C-N bond forming reactions: Intramolecular hydroamination/cyclization/bicyclization of sterically encumbered substrates and intermolecular hydroamination of alkenes, alkynes, vinylarenes, di/trivinylarenes, and methylenecyclopropanes.

摘要

Organolanthanide complexes of the type (η5-Me ₅C₅)₂LnCH(TMS)₂ (Ln = La, Sm), [Me ₂Si(η5-Me₄C₅)₂]SmCH(TMS) ₂, and [Me₂Si(η5-Me₄C ₅)(tBuN)]LnE(TMS)₂ (Ln = Sm, Y, Yb, Lu; E = N, CH) serve as efficient precatalysts for intramolecular hydroamination/cyclization of amine-tethered unactivated 1,2-disubstituted alkenes to afford the corresponding mono- and disubstituted pyrrolidines and piperidines. In addition, chiral C₁-symmetric organolanthanide catalysts of the type Me ₂Si(OHF)(CpR*)LnN(TMS)₂ (OHF = η5-octahydrofluorenyl; Cp = η5-C₅H₃; R* = (−)menthyl; Ln = Sm, Y), and Me₂Si(η5-Me₄C ₅)(CpR*)SmN(TMS)₂ (Cp = η5-H₃C ₅; R* = (−)-menthyl) mediate asymmetric intramolecular hydroamination/cyclization of amines bearing internal olefins and afford chiral 2-substituted piperidine and pyrrolidine in enantioselectivities as high as 68% at 60°C. Thermolysis of (η5-Me₅C₅)₂LaCH(TMS) ₂ in cyclohexane-d₁₂ at 120°C rapidly releases CH ₂(SiMe₃)₂, and leads to possible formation of fulvene (η6-Me₄C₅CH₂-) species. Catalytically active lanthanide-amido complexes (η5-Me ₅C₅)₂La-(NHR)(NH₂R)_n and [Me₂Si(η5-Me₄C₅)( tBuN)]Sm-(NHR)(NH₂R)_n are found to be thermally robust species.; Organolanthanide-catalyzed regioselective intermolecular hydroamination of alkynes R′C≡CMe (R′ = SiMe ₃, C₆H₅, Me), alkenes RCH=CH₂ (R = SiMe₃, CH₃CH₂CH₂), butadiene, vinylarenes ArCH=CH₂ (Ar = phenyl, 4-methylbenzene, naphthyl, 4-fluorobenzene, 4-trifluoromethylbenzene, 4-methoxybenzene, 4dimethylaminobenzene, 4-methylthiobenzene), di/divinylarenes, and methylenecyclopropanes with primary amines R ″NH₂ (R″ = n-propyl, n-butyl, i-butyl, phenyl, 4-methylphenyl, 4-dimethylaminophenyl) affords the corresponding amines and imines. For vinylarenes, intermolecular hydroamination with n-propylamine affords anti-Markovnikov addition product, β-phenylethylamine. In addition, hydroamination of divinylarenes provides a concise synthesis of tetrahydroisoquinoline structures via coupled intermolecular hydroamination/subsequent intramolecular cyclohydroamination sequences. Intermolecular hydroamination of methylenecyclopropane proceeds via highly regioselective exo-methylene C=C insertion into Ln-N bonds, followed by regioselective cyclopropane ring-opening to afford the corresponding imine.