A higher energy conformer of (S)-proline is the active catalyst in intermolecular aldol reaction: Evidence from DFT calculations

Ajitha, M.; Suresh, Cherumuttathu H.

doi:10.1016/j.molcata.2011.05.016

Cited by 21 publications

(16 citation statements)

References 81 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As shown in Scheme 1 , three proline conformers have been considered in this work: two canonical ( P A and P B ) while the third zwitterionic ( P C ), which are in line with previous studies (Rankin et al 2002 ; Yang et al 2010 ; Ajitha and Suresh 2011 ; Yang et al 2015 ). P A and P B are canonical conformers that predominant in gas phase (Eszter et al 2003 ; Alln et al 2004 ; Kapitán et al 2006 ) and become the choice for catalytic studies (Rankin et al 2002 ; Yang et al 2010 ; Ajitha and Suresh 2011 ). P A is slightly less stable than P B with the relative energy of 1.6 kcal/mol (Table 1 and Additional file 1 : Table S1).…”

Section: Resultssupporting

confidence: 81%

“…Single-point energy calculations at the B3LYP/6-311++G (2df, 2pd) and MP2/6-311++G (2df, 2pd) levels of theory were then carried out on these optimized structures. Afterwards, the 6-31+G(d,p) and 6-311++G (2df, 2pd) basis sets were respectively designated as bs1 and bs2, and unless otherwise noted, all energies were reported at the B3LYP/bs2//B3LYP/bs1 level, which has been sufficiently validated before (Li et al 2011 ; Kim et al 2014 ; Yang et al 2009 ; Rankin et al 2002 ; Yang et al 2010 ; Ajitha and Suresh 2011 ) and in this work.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Stabilization of zwitterionic versus canonical proline by water molecules

2016

View full text Add to dashboard Cite

At physiological conditions, a majority of biomolecules (e.g., amino acids, peptides and proteins) exist predominantly in the zwitterionic form that usually decides the biological functions. However, zwitterionic amino acids are not geometrically stable in gas phase and this seriously hampers the understanding of their structures, properties and biological functions. To this end, one of the recent research focuses is to demonstrate the stabilization effects of zwitterionic amino acids. Relative stabilities of canonical conformers are dependent on water contents, while zwitterionic stability improves monotonously and pronouncedly with increase of water contents. We find that one water molecule can render zwitterionic proline geometrically stable, and stabilities of different zwitterionic amino acids increase as glycine

show abstract

Section: Resultssupporting

confidence: 81%

Section: Methodsmentioning

confidence: 99%

Stabilization of zwitterionic versus canonical proline by water molecules

2016

View full text Add to dashboard Cite

show abstract

“…It has been established [ 21 , 23 ] that structural interconversion from 1a to 1b does not require a large energy barrier. This means that the two conformers are always present in a reaction vessel.…”

Section: Resultsmentioning

confidence: 99%

“…As pertaining to the proline catalyzed aldol reaction, Ajitha and Suresh proposed in 2011 [ 21 ], based on a density functional theory (DFT) study, that the lowest energy conformer (LEC) of ( S ) proline [ 22 ] was inactive with its reaction pathway not proceeding beyond an initial proton transfer step. In 2019, we confirmed these findings using the REP-FAMSEC technique [ 23 ] (Reaction Energy Profile–Fragment Attributed Molecular System Energy Change).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Molecular-Wide and Electron Density-Based Approach in Exploring Chemical Reactivity and Explicit Dimethyl Sulfoxide (DMSO) Solvent Molecule Effects in the Proline Catalyzed Aldol Reaction

Cukrowski¹,

Dhimba²,

Riley³

2022

Molecules

View full text Add to dashboard Cite

Modelling of the proline (1) catalyzed aldol reaction (with acetone 2) in the presence of an explicit molecule of dimethyl sulfoxide (DMSO) (3) has showed that 3 is a major player in the aldol reaction as it plays a double role. Through strong interactions with 1 and acetone 2, it leads to a significant increase of energy barriers at transition states (TS) for the lowest energy conformer 1a of proline. Just the opposite holds for the higher energy conformer 1b. Both the ‘inhibitor’ and ‘catalyst’ mode of activity of DMSO eliminates 1a as a catalyst at the very beginning of the process and promotes the chemical reactivity, hence catalytic ability of 1b. Modelling using a Molecular-Wide and Electron Density-based concept of Chemical Bonding (MOWED-CB) and the Reaction Energy Profile–Fragment Attributed Molecular System Energy Change (REP-FAMSEC) protocol has shown that, due to strong intermolecular interactions, the HN-C-COOH (of 1), CO (of 2), and SO (of 3) fragments drive a chemical change throughout the catalytic reaction. We strongly advocate exploring the pre-organization of molecules from initially formed complexes, through local minima to the best structures suited for a catalytic process. In this regard, a unique combination of MOWED-CB with REP-FAMSEC provides an invaluable insight on the potential success of a catalytic process, or reaction mechanism in general. The protocol reported herein is suitable for explaining classical reaction energy profiles computed for many synthetic processes.

show abstract

Activation Modes In Asymmetric Organocatalysis

Moyano¹

2013

Stereoselective Organocatalysis

View full text Add to dashboard Cite

A higher energy conformer of (S)-proline is the active catalyst in intermolecular aldol reaction: Evidence from DFT calculations

Cited by 21 publications

References 81 publications

Stabilization of zwitterionic versus canonical proline by water molecules

Stabilization of zwitterionic versus canonical proline by water molecules

A Molecular-Wide and Electron Density-Based Approach in Exploring Chemical Reactivity and Explicit Dimethyl Sulfoxide (DMSO) Solvent Molecule Effects in the Proline Catalyzed Aldol Reaction

Activation Modes In Asymmetric Organocatalysis

Contact Info

Product

Resources

About