Journal ArticleDOI
Constrained β-Proline Analogues in Organocatalytic Aldol Reactions: The Influence of Acid Geometry
TLDR
A comparative density functional theory study of proline 1, beta-proline 5b, and 11 in the latter reaction revealed the origin of the improved enantioselectivity of 11 over 5b.Abstract:
7-Azabicyclo[2.2.1]heptane-2-carboxylic acid 11 was prepared in enantiopure form, and its catalytic potential in the direct aldol reaction between acetone and 4-nitrobenzaldehyde was assessed. The bicyclic system was found to be more selective than its monocyclic analogue β-proline 5b. A comparative density functional theory study of proline 1, β-proline 5b, and 11 in the latter reaction revealed the origin of the improved enantioselectivity of 11 over 5b. The geometry of the carboxylic acid group in the transition states, which depended critically on pyrrolidine ring conformation, was found to play a key role.read more
Citations
More filters
Journal ArticleDOI
Fluorine Conformational Effects in Organocatalysis: An Emerging Strategy for Molecular Design
TL;DR: This minireview highlights examples of catalyst refinement by introduction of an aliphatic C-F bond which functions as a chemically inert steering group for conformational control.
Journal ArticleDOI
The Houk–List transition states for organocatalytic mechanisms revisited
Alan Armstrong,Roberto A. Boto,Roberto A. Boto,Paul Dingwall,Julia Contreras-García,Julia Contreras-García,Matthew J. Harvey,Nicholas J. Mason,Henry Rzepa +8 more
TL;DR: The ten year old Houk–List model for rationalising the origin of stereoselectivity in the organocatalysed intermolecular aldol addition is revisited, using a variety of computational techniques that have been introduced or improved since the original study.
Journal ArticleDOI
Konformative Fluoreffekte in der Organokatalyse: eine neuartige Strategie zum molekularen Design
TL;DR: In this paper, beispiele zur Verbesserung von Katalysatoren durch die Einfuhrung einer aliphatischen C-F-Bindung erlautert, die als eine chemisch inerte dirigierende Gruppe zur Steuerung der Konformation dient.
Journal ArticleDOI
Highly selective asymmetric Rh-catalyzed hydroformylation of heterocyclic olefins.
TL;DR: Application of the small bite-angle ligands L1 and L2 in the highly selective asymmetric hydroformylation (AHF) of the challenging substrate 2,3-dihydrofuran yielded the 2-carbaldehyde as the major regioisomer in up to 68% yield (with ligand L2) along with good ee's of up to 62%.
Journal ArticleDOI
β-Amino Acid Catalyzed Asymmetric Michael Additions: Design of Organocatalysts with Catalytic Acid/Base Dyad Inspired by Serine Proteases
Hui Yang,Ming Wah Wong +1 more
TL;DR: A new type of chiral β-amino acid catalyst has been computationally designed, mimicking the enzyme catalysis of serine proteases, based on the bioinspired catalytic acid/base dyad, namely, a carboxyl and imidazole pair.
References
More filters
Journal ArticleDOI
Density‐functional thermochemistry. III. The role of exact exchange
TL;DR: In this article, a semi-empirical exchange correlation functional with local spin density, gradient, and exact exchange terms was proposed. But this functional performed significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.
Journal ArticleDOI
Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density
TL;DR: Numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, show that density-functional formulas for the correlation energy and correlation potential give correlation energies within a few percent.
Journal ArticleDOI
A new integral equation formalism for the polarizable continuum model: Theoretical background and applications to isotropic and anisotropic dielectrics
TL;DR: In this paper, a new integral equation formulation of the polarizable continuum model (PCM) is presented, which allows one to treat in a single approach dielectrics of different nature: standard isotropic liquids, intrinsically anisotropic medialike liquid crystals and solid matrices, or ionic solutions.
Journal ArticleDOI
An improved algorithm for reaction path following
TL;DR: In this article, a second order algorithm for finding points on a steepest descent path from the transition state of the reactants and products is presented. But the points are optimized so that the segment of the reaction path between any two adjacent points is given by an arc of a circle, and the gradient at each point is tangent to the path.
Journal ArticleDOI
Ab initio study of solvated molecules: A new implementation of the polarizable continuum model
TL;DR: In this article, an efficient version of the polarizable continuum solvation model was implemented in the GAUSSIAN94 package, which exploits a new definition of surface elements area, and a direct formulation of the electrostatic self-consistent problem.
Related Papers (5)
Asymmetric synthesis of bicyclic intermediates of natural product chemistry
Zoltan G. Hajos,David R. Parrish +1 more