Enantioselective addition of diethylzinc to aromatic aldehydes catalyzed by chiral BINOL-functionalized nanoporous graphene oxides

Catalytic N2 Reduction to Silylamines and Thermodynamics of N2 Binding at Square Planar Fe

“…Treatment of Fe I Br with NaBAr F 4 (Ar F = 3,5-bis (trifluoromethyl)phenyl) or KB(C 6 F 5 ) 4 in fluorobenzene immediately changes the solution color from orange to deep purple, affording [Fe I ] + (S = 1/2, μ eff = 1.5 μ B , Scheme 1). The molecular structure of [Fe I ] + [B(C 6 F 5 ) 4 ] − confirms the distorted square planar geometry, formally a 15-electron species with a τ 4 value of 0.23 (τ 4 = 0 for square planar, τ 4 = 1 for tetrahedral; 26 Figure 2). Aside from four Fe−P bonds, the next closest atomic contact to Fe in the solid-state is a phenylphosphine ortho-CH interaction, (Fe•••H20 = 2.786 Å, Fe•••C20 = 3.389 Å), which is best described as a weak σ-agostic interaction.…”

Application of chiral recyclable catalysts in asymmetric catalysis

“…In 2019, Yan et al published a study introducing a novel heterogeneous catalyst 29-Ti ( Scheme 29 ), based on graphene oxide. 116 The catalyst consists of an amino-terminated BINOL molecule, which is covalently linked to the graphene oxide sheet. The preparation of this graphene oxide catalyst involved the initial oxidation of commercial graphene oxide to nanoporous graphene oxide in an acidic environment.…”

Graphene-based materials for asymmetric catalysis

“…The chiral BINOL-functionalized nanoporous graphene oxides-catalyzed conjugate addition of diethylzinc to aromatic aldehydes was performed by Yan and co-workers. 48 To prepare GO-BINOL-Ti catalyst, a commercial GO was first oxidized in an acidic environment to make nano-porous GOs and then enantiopure (R)-or (S)-NH2-BINOLs were covalently attached to the nanoporous GOs, and this GO-BINOL was subsequently treated with Ti(Oi-Pr)4. Applied in asymmetric addition of ZnEt2, the GO-BINOL-Ti catalyst displayed a very good activity (resulting in 99% conversion), but relatively low enantioselectivity (up to 45% ee, Figure 14) as compared with the use of R-BINOL as catalyst (90% ee).…”