Intramolecular Hydroamination/Cyclization of Aminoalkenes Catalyzed by Ln[N(SiMe₃)₂]₃ Grafted onto Periodic Mesoporous Silicas

Abstract

Homoleptic rare-earth metal silylamide complexes Ln[N(SiMe(3))(2)](3) (Ln = Y, La, Nd) were grafted onto a series of partially dehydroxylated periodic mesoporous silica (PMS) supports, SBA-15(-500) (d(p) = 7.9 nm), SBA-15LP(-500) (d(p) = 16.6 nm), and MCM-41(-500) (d(p) = 4.1 nm). The hybrid materials Ln[N(SiMe(3))(2)](3)@PMS efficiently catalyze the intramolecular hydroamination/cyclization reaction of 2,2-dimethyl-4-penten-1-amine. Under the prevailing slurry conditions the metal size (Y > La > Nd), the pore size, and the particle morphology affect the catalytic performance. Material Y[N(SiMe(3))(2)](3)@SBA-15LP(-500) displayed the highest activity (TOF = up to 420 h(-1) at 60 °C), with the extralarge pores minimizing restrictive product inhibition and substrate diffusion effects. The catalytic activity of Y[N(SiMe(3))(2)](3)@SBA-15LP(-500) is found to be much higher than that of the molecular counterpart (TOF = up to 54 h(-1)), and its recyclability is demonstrated.

N‐Heterocyclic Carbene–Ytterbium Amide as a Recyclable Homogeneous Precatalyst for Hydrophosphination of Alkenes and Alkynes

“…The reactionw ith 1,1-diphenyl alkene at room temperature yielded as ingleh ydrophosphination product in almostq uantitative yield ( Table 3, entry 1). In contrast, cis-a nd trans-1,2-di- (12), C7ÀYb1ÀC7* 79.28 (13). 3:Yb1ÀP1 2.9645(7), Yb1ÀP2 2.8914(8), Yb1ÀC25 2.5859 (19), Yb1ÀC322 .567(2), Yb1ÀC39 2.591(2);P1 ÀYb1ÀP2 147.350 (16), C25ÀYb1ÀC32 111.29(6), C25ÀYb(1) ÀC39 104.63(6), C32ÀYb1À C39 143.70(6).…”

Silylamide Complexes of Chromium(II), Manganese(II), and Cobalt(II) Bearing the Ligands N(SiHMe2)2 and N(SiPhMe2)2

“…18 Ln[N-(SiMe 3 ) 2 ] 3 /SBA-15 hybrid materials (Ln = Y, La, Nd; SBA-15 = high-surface periodic mesoporous silica) exhibit better performance than in the intramolecular hydroamination cyclization of aminoalkenes than the molecular counterparts. 19 Grafting of lanthanide and aluminum bis(dimethylsilyl)amide complexes M[N(SiHMe 2 ) 2 ] 3 (thf) x and subsequent ligand exchange against 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione generates surface species that are active in the hetero-Diels−Alder cyclization (Danishefsky transformation). 20 The surface chemistry of bis(dimethylphenylsilyl)amide complexes is less exploited.…”

Facile method to synthesize platelet SBA-15 silica with highly ordered large mesopores

“…However, the resulting long parallel nanopores may exhibit slower diffusion and thus reduced accessibility of molecules, especially those with high molecular weights, such as enzymes [10][11][12], and thus they may be less efficient in heterogeneous catalysis [9]. The pore accessibility in SBA-15 can be improved by shortening the mesopore length [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24], fostering the access to the cylindrical mesopores through complementary micropores/mesopores in the framework [10], or enlarging the mesopore diameter [5,9,12,[25][26][27][28][29]. The first two strategies usually involve the control of the SBA-15 particle morphology.…”