An Enantioselective Synthesis of Spirobilactams through Copper‐Catalyzed Intramolecular Double N‐Arylation and Phase Separation

Abstract

Spirobicyclic structures are versatile building blocks for functional chiral molecules. An enantioselective synthesis of chiral spirobilactams via a copper-catalyzed double N-arylation was developed. Amplification of solution ee by in situ precipitation of the racemate was observed with this method and enantioenriched spirobilactams were obtained with excellent ee values through simple solid-solution phase separation.

Effect of Residual Lithium Rearrangement on Ni‐rich Layered Oxide Cathodes for Lithium‐Ion Batteries

“…Then ext-generation of Li-ion battery (LIB) cathodes requires higher energy density,l onger cyclability,a nd better safety to enablet heir successful use for energy storage in electric vehicles (EVs)a nd plug-in hybrid electric vehicles (PHEVs). [1][2][3] Nickel-rich layered oxides (LiNi x M 1Àx O 2 ;M = Mn, Co,a nd Al; x > 0.5) are among the most promising candidate materials because of their high capacity,e xcellentr ate capability,a nd low cost. However, Ni-rich layered oxides show poor cyclability at high operating temperatures (> 45 8C) and high voltages (> 4.3 V) because of the presence of reactive and unstable Ni 4 + ions in the delithiated state.…”

“…However, Ni-rich layered oxides show poor cyclability at high operating temperatures (> 45 8C) and high voltages (> 4.3 V) because of the presence of reactive and unstable Ni 4 + ions in the delithiated state. [3][4][5][6] Thep resence of unreacted lithium on the surface of Ni-rich layered oxides leads to the formationo fl ithium impurities (termed residual lithium) such as lithium carbonates (Li 2 CO 3 )a nd lithium hydroxides (LiOH). These species are extremely prone to reactions with atmospheric carbond ioxide (CO 2 )and moisture.…”

In situ Formed Co(TCNQ)2 Metal‐Organic Framework Array as a High‐Efficiency Catalyst for Oxygen Evolution Reactions

“…TOF can be cal-culated using the following equation (3 and 4) and the TOF value for Co(TCNQ) 2 /Co is 0.66 mol s À1 at overpotential of 380 mV,m ore TOF values are shown in Figure 4c.O ur Co(TCNQ) 2 /Co has higher TOF value than that of other reported Co-based catalysts like MnCo 2 S 4 ( % 0.21 mol s À1 , h = 380 mV) [47] and Co 3 S 4 ( % 0.16 mol s À1 , h = 380 mV). [48] Faradic efficiency (FE) is another significant parameter to evaluate water oxidation activity of ac atalyst. In this work, we obtained the FE by comparing the quantity of practically evolved oxygen with theoretically calculated oxygen (assuming 100 %F E).…”

Catalytic Enantioselective Synthesis of C1‐ and C2‐Symmetric Spirobiindanones through Counterion‐Directed Enolate C‐Acylation

“…[11] We consideredt hat an alternative approach thatd id not utilize ap reformed enolate derivative could be extremelyv aluable, buta lsor ecognized that this was likelyt ob ec hallengingd ue to competitive O-acylation, especially as the oxygen of an enolate is intrinsically the most nucleophilic site; [12] to ourknowledge no methods for the direct catalytic enantioselective C-acylation of ketones have been disclosed.W er ationalizedt hati ntramoleculara cylation of ak etone enolate couldg eometricallyd isfavour reactiono n oxygen andf avour the desired C-acylation. [16] We prepared asuitable substrate 7 in which the acyl group was activated as ap henyl ester in three steps from indan-1one. Spiro compounds are valuable intermediates in synthesis,m aterials and catalysis, [14] but catalytic enantioselective routesf or their synthesis arerelativelyunderdeveloped.…”

“…[15] Catalytice nantioselective methodsf or the generationo fa xially chirals piro compounds are particularly rare. [16] We prepared asuitable substrate 7 in which the acyl group was activated as ap henyl ester in three steps from indan-1one. [17] Upon exposure of 7 to tetrabutylammonium bromide (TBAB) and 50 %aqueous potassium carbonate in toluene at room temperature,w eo bserved smooth cyclization to the racemic C 2 -symmetric spirobiindanone 9,with no trace of Oacylation observed ( Table 1, entry 1).…”