Converting the role of LiClO4 from salting-in to salting-out in Diels-Alder reactions by solvent manipulation

2003 ◽  
Vol 16 (9) ◽  
pp. 633-635 ◽  
Author(s):  
Suvarna S. Deshpande ◽  
Sanjay S. Pawar ◽  
Usha Phalgune ◽  
Anil Kumar
Keyword(s):  
Diels Alder ◽  
Salting Out

scholarly journals Theoretical Insight into the Reversal of Chemoselectivity in Diels-Alder Reactions of α,β-Unsaturated Aldehydes and Ketones Catalyzed by Brønsted and Lewis Acids

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 38-49
Author(s):  
Lakhdar Benhamed ◽  
Sidi Mohamed Mekelleche ◽  
Wafaa Benchouk
Keyword(s):  
Lewis Acids ◽  
Major Product ◽  
Diels Alder ◽  
Unsaturated Ketone ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones ◽  
Theoretical Insight ◽  
Insight Into ◽  
Good Agreement

Experimentally, a reversal of chemoselectivity has been observed in catalyzed Diels–Alder reactions of α,β-unsaturated aldehydes (e.g., (2E)-but-2-enal) and ketones (e.g., 2-hexen-4-one) with cyclopentadiene. Indeed, using the triflimidic Brønsted acid Tf2NH as catalyst, the reaction gave a Diels–Alder adduct derived from α,β-unsaturated ketone as a major product. On the other hand, the use of tris(pentafluorophenyl)borane B(C6F5)3 bulky Lewis acid as catalyst gave mainly the cycloadduct of α,β-unsaturated aldehyde as a major product. Our aim in the present work is to put in evidence the role of the catalyst in the reversal of the chemoselectivity of the catalyzed Diels–Alder reactions of (2E)-but-2-enal and 2-Hexen-4-one with cyclopentadiene. The calculations were performed at the ωB97XD/6-311G(d,p) level of theory and the solvent effects of dichloromethane were taken into account using the PCM solvation model. The obtained results are in good agreement with experimental outcomes.

ChemInform Abstract: Switched Role of Fullerene in the Diels-Alder Reaction: Facile Addition of Dienophiles to the Conjugated Fullerene Diene Moiety.

ChemInform ◽  
2009 ◽  
Vol 40 (24) ◽  
Author(s):  
Jiayao Yao ◽  
Zuo Xiao ◽  
Jianxin Zhang ◽  
Xiaobing Yang ◽  
Liangbing Gan ◽  
...  
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction

Concerted and Diradical Stepwise Mechanisms in the Diels-Alder Reactions of Phosphinine and Phosphinine Sulfide: A DFT Investigation

2008 ◽  
Vol 63 (3) ◽  
pp. 321-330 ◽  
Author(s):  
Raj K. Bansal ◽  
Neelima Gupta ◽  
Surendra K. Kumawat
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Diels Alder ◽  
Dimethyl Acetylenedicarboxylate ◽  
Functional Theory ◽  
Concerted Mechanism ◽  
Density Functional Theory Level ◽  
The Density Functional Theory

Computations of the concerted and diradical stepwise mechanisms of the Diels-Alder (DA) reactions on the >C=P− functionality of phosphinine and phosphinine sulfide with 1,3-butadiene at the density functional theory level B3LYP/6-311++G**//B3LYP/6-31G** give the values of energy of concert as 10.7 and 2.6 kcal mol−1, respectively. Similarly, the DA reaction of dimethyl acetylenedicarboxylate (DMAD) with the −CH=CH−CH=P− moiety of phosphinine or its sulfide has been investigated theoretically at the same level of theory. The results reveal that in the DA reaction of phosphinine, the role of sulfur is to oxidize phosphorus to generate a phosphinine sulfide intermediate, which subsequently undergoes DA reaction with 2,3-dimethylbutadiene or DMAD by a concerted mechanism to afford the respective cycloadducts.

ChemInform Abstract: Highly Diastereoselective Diels-Alder Reaction Mediated by a Chiral Auxiliary Derived from Amino Indanol: The Role of Conformation on Diastereoselectivity.

ChemInform ◽  
2010 ◽  
Vol 27 (5) ◽  
pp. no-no
Author(s):  
I. W. DAVIES ◽  
C. H. SENANAYAKE ◽  
L. CASTONGUAY ◽  
R. D. LARSEN ◽  
T. R. VERHOEVEN ◽  
...  
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Chiral Auxiliary ◽  
Diels Alder Reaction

Towards the Synthesis of a Dewar Furan Stabilized by a Pinching Group: the Role of Dewar o-Xylylenes as Dienes and Dienophiles

1991 ◽  
Vol 44 (9) ◽  
pp. 1293 ◽  
Author(s):  
RN Warrener ◽  
IG Pitt ◽  
RA Russell
Keyword(s):  
Active Species ◽  
Diels Alder

The synthesis of a photosubstrate (42) suitable for the production of a Dewar furan (46) containing a four-carbon bridge at the 1,4-position is described. The route to this product illustrates an example of transfer technology in synthesis, by using the oxanorbornadiene (29). Other active species such as Dewar benzene (32) and Dewar o-xylylene (50) play key roles as intermediates. Diels-Alder cycloadditions are also central to the overall strategy, and some observations are made regarding the facial specificities operating, especially in regard to Dewar o-xylylene (50) and its dimerization. Attempts to isolate the photoproducts, presumably involving the Dewar furan (46) as intermediate, were unsuccessful.

scholarly journals On the Role of Hydrogen Bond Strength and Charge Transfer of a Diels-Alder Reaction On-Water: Semiempirical and Free Energy Calculations.

2021 ◽  
Author(s):  
Andrés Henao Aristizàbal ◽  
Yomna Gohar ◽  
René Whilhelm ◽  
Thomas D. Kühne
Keyword(s):  
Hydrogen Bond ◽  
Free Energy ◽  
Charge Transfer ◽  
Hydrogen Bonds ◽  
Density Functional ◽  
Alder Reaction ◽  
Free Energy Calculations ◽  
Diels Alder ◽  
Diels Alder Reaction

Accelerated chemistry at the interface with water has received increasing attention. The mechanisms behind the enhanced reactivity On-Water are not yet clear. In this work we use a Langevin scheme in the spirit of second generation Car-Parrinello to accelerate the second-order density functional Tight-Binding (DFTB2) method in order to investigate the free energy of two Diels-Alder reaction On-Water: the cycloaddition between cyclopentadiene and ethyl cinnamate or thionocinnamate. The only difference between the reactants is the substitution of a carbonyl oxygen for a thiocarbonyl sulfur, making possible the distinction between them as strong and weak hydrogen-bond acceptors. We find a different mechanism for the reaction during the transition states and uncover the role of hydrogen bonds along with the reaction path. Our results suggest that acceleration of Diels-Alder reactions do not arise from an increased number of hydrogen bonds at the transition state and charge transfer plays a significant role. However, the presence of water and hydrogen-bonds is determinant for the catalysis of these reactions.

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