<scp>DFT</scp> study on the structure and racemization mechanism of 2‐amino‐2′‐hydroxy‐1,1′‐binaphthyl

Da, Liangguo; He, Jie; Hu, Lifang

doi:10.1002/poc.3900

Cited by 4 publications

(4 citation statements)

References 23 publications

(33 reference statements)

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“…It would appear, then, that the dominating characteristic is the size of the substituent. Previous theoretical results obtained for large substituents are consistent with this assumption (computed rotational barriers for 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl and 2-amino-2′-hydroxy-1,1′-binaphthyl are 49.4 and 40.4 kcal/mol, respectively). The barrier for H is by far the lowest, whereas the highest barrier occurs for the bulky phenyl group.…”

Section: Resultssupporting

confidence: 75%

Optical Stability of 1,1′-Binaphthyl Derivatives

Tkachenko

Scheiner

2019

ACS Omega

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The racemization process of various 1,1′-binaphthyl derivatives is studied by quantum calculations. The preferred racemization pathway passes through a transition state belonging to the C i symmetry group. The energy barrier for this process is independent of solvation, the electron-withdrawing/releasing power of substituents, or their ability to engage in H-bonds within the molecule. The primary factor is instead the substituent size. The barrier is thus reduced when the −OH groups of 1,1′-bi-2-naphthol are replaced by H. There is a drop in the barrier also when the substituents are moved from the 2,2′ positions to 6,6′, where they will not come close to one another in the transition state. Upon removal of the peripheral aromatic rings of the binaphthyl system, the biphenyl system undergoes a facile racemization. It is concluded that the optimal means of improving optical stability of 1,1′-binaphthyl systems is the substitution of large bulky groups in the 2,2′ positions.

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Section: Resultssupporting

confidence: 75%

Optical Stability of 1,1′-Binaphthyl Derivatives

Tkachenko

Scheiner

2019

ACS Omega

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“…We begin by examining the uncatalyzed and graphenecatalyzed chirality inversions of BINOL in solution. A number of DFT studies have considered the inversion of binaphthyl derivatives (including BINOL) in the gas-phase [8,[34][35][36] and established that racemization consistently proceeds through a kinetically preferred anti-type transition structure with C i symmetry. Therefore, we focus here on the anti-type reaction pathway.…”

Section: Solvent Effects On the Graphene-catalyzed Racemization Of Binolmentioning

confidence: 99%

Pristine Graphene as a Racemization Catalyst for Axially Chiral BINOL

2020

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Despite versatile applications of functionalized graphene in catalysis, applications of pure, unfunctionalized graphene in catalysis are in their infancy. This work uses both computational and experimental approaches to show that single‐layer graphene can efficiently catalyze the racemization of axially chiral BINOL in solution. Using double‐hybrid density functional theory (DHDFT) we calculate the uncatalyzed and catalyzed Gibbs free reaction barrier heights in a number of representative solvents of varying polarity: benzene, diphenyl ether, dimethylformamide (DMF), and water. These calculations show that (i) graphene can achieve significant catalytic efficiencies (▵▵G≠cat) varying between 47.2 (in diphenyl ether) and 60.7 (in DMF) kJ mol−1. An energy decomposition analysis reveals that this catalytic activity is driven by electrostatic and dispersion interactions. Based on these computational results, we explore the graphene‐catalyzed racemization of axially chiral BINOL experimentally and show that single‐layer graphene can efficiently catalyze this process. Whilst the uncatalyzed racemization requires high temperatures of over 200 °C, a pristine single‐layer graphene catalyst makes it accessible at 60 °C.

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“…Being one of the most common motifs in the backbones of asymmetric metal and organocatalysts, − the racemizations of biaryl compounds have been studied extensively both computationally and experimentally. − Here, we focus on the racemizations of 1,1′-binaphthyl ( 1 ) and its synthetically highly relevant derivative 1,1′-binaphthyl-2,2′-diol (BINOL) ( 2 ) which forms the starting material to a myriad of chiral catalysts. − Table gives experimentally determined rotational barriers for compounds 1 and 2 .…”

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confidence: 99%