A combined synthetic and ab initio study of chiral oxazaborolidines structure and enantioselectivity relationships

Quallich, George J.; Blake, James F.; Woodall, Teresa M.

doi:10.1021/ja00098a012

Cited by 86 publications

(43 citation statements)

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“…The -N bond distance is in the order of 1.6 Å , in agreement with results earlier reported for complex 1 [28], and in the systems without the B-H-B bonding in the order of 1.7 Å . The latter value is in a good agreement with theoretical values by Quallich et al [32].…”

Section: Resultssupporting

confidence: 92%

“…Linney et al [28] investigated model oxazaborolidine-borane complex within the HF, MP2, and AM1 approximations. Moreover, theoretical studies on the mechanism of reduction of ketones were carried out using the semiempirical MNDO [29] and AM1 [30,31] methods as well as within the ab initio techniques and the density functional theory (DFT) [32][33][34]. Reduction of oxime ethers [35] and imines [36] has been the subject of detailed analyses using DFT.…”

Section: Introductionmentioning

confidence: 99%

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The B–H–B bridging interaction in B-substituted oxazaborolidine–borane complexes: a theoretical study

et al. 2012

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Ten oxazaborolidine-borane complexes, nine among them boron-substituted (B-R, R=CH 3 , CF 3 , and OCH 3 ), are carefully analysed using quantum-chemistry methods to determine their equilibrium geometries and the corresponding oxazaborolidine-borane interaction energies. It is observed that in all B-trifluoromethyl substituted oxazaborolidine-borane complexes and in one B-methyl substituted complex the B-H-B bond is formed and the interaction energies are 1.5-2.5 times as large as in other investigated complexes. We believe that the presented results may be helpful in experimental recognition of oxazaborolidine-borane complexes which may appear, inter alia, as reaction intermediates.keywords B-substituted oxazaborolidine-borane complexes Á B-H-B bond Á Ab initio calculations Á Density functional theory calculations Á Intermolecular interaction energy

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

The B–H–B bridging interaction in B-substituted oxazaborolidine–borane complexes: a theoretical study

et al. 2012

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“…As a cheap and commercially available chiral source, camphor is structurally rigid and can be easily modified to form two chiral centres at atoms C-2, C-3. However, to the best of our knowledge, the derivatives from (R)-(+)-camphor were rarely used as chiral ligands in asymmetric reduction of prochiral ketones [10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Asymmetric reduction of prochiral ketones with borane using chiral squaric amino alcohols derived from camphor as catalysts

Zou

Zhang

et al. 2005

Journal of Molecular Catalysis A: Chemical

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“…2), the reduction of the oxime to generate another chiral carbon, and finally the chiral alcohol A is generated. www.scichina.com www.springerlink.com Many quantum chemical studies on the enantioselective reduction catalyzed by oxazaborolidine were performed and some interesting results were obtained [5][6][7][8][9][10][11][12][13][14][15][16][17][18] . Up to now, however, almost all the reported studies are computations of the enantioselective reduction of prochiral ketone with borane catalyzed by oxazaborolidine, and only one carbonyl bond is reduced in the reaction.…”

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confidence: 99%

Density functional study on enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine

Li¹,

Zheng

Tian

2006

SCI CHINA SER B

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The enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine is discussed by the density functional theory (DFT) method. The main intermediates and transition states for this reaction are optimized completely at the B3LYP/6-31g(d) level, and the transition states are verified by vibrational modes. As shown, the chirality-controlled steps for this reaction are the hydride transfer from borane to carbonyl carbon and oxime carbon of keto oxime ether, and the chirality for the reduced products is determined in these two reaction steps. In all examined reaction paths, the first hydride is transferred via a six-membered ring and the second hydride via a five-membered ring or a four-membered ring.

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A combined synthetic and ab initio study of chiral oxazaborolidines structure and enantioselectivity relationships

Cited by 86 publications

References 0 publications

The B–H–B bridging interaction in B-substituted oxazaborolidine–borane complexes: a theoretical study

The B–H–B bridging interaction in B-substituted oxazaborolidine–borane complexes: a theoretical study

Asymmetric reduction of prochiral ketones with borane using chiral squaric amino alcohols derived from camphor as catalysts

Density functional study on enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine

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