scholarly journals Transition state analysis of an enantioselective Michael addition by a bifunctional thiourea organocatalyst

2019 ◽  
Vol 17 (16) ◽  
pp. 3934-3939 ◽  
Author(s):  
Joseph A. Izzo ◽  
Yaroslaw Myshchuk ◽  
Jennifer S. Hirschi ◽  
Mathew J. Vetticatt
Keyword(s):  
Dft Calculations ◽  
Transition State ◽  
Michael Addition ◽  
Transition Structure ◽  
State Analysis

Transition structure for the bifunctional thiourea catalyzed Michael addition using 13C KIEs and DFT calculations.

Reactions of an Aluminium(I) Reagent with 1,2-, 1,3- and 1,5-Dienes: Dearomatisation, Reversibility, and a Pericyclic Mechanism

2019 ◽  
Author(s):  
Clare Bakewell ◽  
Martí Garçon ◽  
Richard Y Kong ◽  
Louisa O'Hare ◽  
Andrew J. P. White ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Dft Calculations ◽  
Transition State ◽  
Reaction Pathways ◽  
Aromatic Rings ◽  
Aromatic Character ◽  
Pericyclic Reaction

The reactions of an aluminium(I) reagent with a series of 1,2-, 1,3- and 1,5-dienes are reported. In the case of 1,3-dienes the reaction occurs by a pericyclic reaction mechanism, specifically a cheletropic cycloaddition, to form aluminocyclopentene containing products. This mechanism has been interrogated by stereochemical experiments and DFT calculations. The stereochemical experiments show that the (4+1) cycloaddition follows a suprafacial topology, while calculations support a concerted albeit asynchronous pathway in which the transition state demonstrates aromatic character. Remarkably, the substrate scope of the (4+1) cycloaddition includes dienes that are either in part, or entirely, contained within aromatic rings. In these cases, reactions occur with dearomatisation of the substrate and can be reversible. In the case of 1,2- or 1,5-dienes complementary reactivity is observed; the orthogonal nature of the C=C π-bonds (1,2-diene) and the homoconjugated system (1,5-diene) both disfavour a (4+1) cycloaddition. Rather, reaction pathways are determined by an initial (2+1) cycloaddition to form an aluminocyclopropane intermediate which can in turn undergo insertion of a further C=C π-bond leading to complex organometallic products that incorporate fused hydrocarbon rings.

scholarly journals Transition State Analysis of Thymidine Hydrolysis by Human Thymidine Phosphorylase

2010 ◽  
Vol 132 (38) ◽  
pp. 13425-13433 ◽  
Author(s):  
Phillip A. Schwartz ◽  
Mathew J. Vetticatt ◽  
Vern L. Schramm
Keyword(s):  
Transition State ◽  
Thymidine Phosphorylase ◽  
State Analysis

scholarly journals Transient [3,3] Cope rearrangement of 3,3-dicyano-1,5-dienes: computational analysis and 2-step synthesis of arylcycloheptanes

2018 ◽  
Vol 9 (46) ◽  
pp. 8760-8764 ◽  
Author(s):  
Ehsan Fereyduni ◽  
Jacob N. Sanders ◽  
Gabriel Gonzalez ◽  
K. N. Houk ◽  
Alexander J. Grenning
Keyword(s):  
Transition State ◽  
Computational Analysis ◽  
Cope Rearrangement ◽  
State Analysis

Unexpectedly mild [3,3] rearrangement computed transition state analysis, regio- and diastereoselecitve transformations multicomponent couplings, convergent 2-step arylcycloheptene synthesis.

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