Record Details

Insights on co-catalyst-promoted enamine formation between dimethylamine and propanal through ab initio and density functional theory study

DSpace at IIT Bombay

View Archive Info
 
 
Field Value
 
Title Insights on co-catalyst-promoted enamine formation between dimethylamine and propanal through ab initio and density functional theory study
 
Creator PATIL, MP
SUNOJ, RB
 
Subject asymmetric michael addition
diels-alder reactions
organocatalytic conjugate addition
polarizable continuum model
proton-transfer process
rabbit muscle aldolase
carbonyl addition
ionic liquids
enantioselective organocatalysis
alpha,beta-unsaturated aldehydes
 
Description The mechanistic details on enamine formation between dimethylamine and propanal are unraveled using the ab initio and density functional theory methods. The addition of secondary amine to the electrophile and simultaneous proton transfer results in a carbinolamine intermediate, which subsequently undergoes dehydration to form enamine. The direct addition of amine as well as the dehydration of the resulting carbinolamine intermediate is predicted to possess fairly high activation barrier implying that a unimolecular process is unlikely to be responsible for enamine formation. Different models are therefore proposed which could explain the relative ease of enamine formation under neat condition as well as under the influence of methanol as the co-catalyst. The explicit inclusion of either the reagent or the co-catalyst is considered in the transition states as stabilizing agents. The participation of the reagent or the co-catalyst as a monofunctional ancillary species is found to stabilize the transition states relative to the unassisted or the direct addition/dehydration pathways. The reduction in enthalpy of activation is found to be much more dramatic when two co-catalysts participate in an active bifunctional mode in the rate-determining dehydration step. The transition structures exhibited characteristic features of a relay proton transfer mechanism. The free energy of activation associated with the two methanol-assisted pathway is found to be 16.7 kcal/mol lower than that of the unassisted pathway. The results are found to be in concurrence with the available reports on the rate acceleration by co-catalysts in the Michael reaction between enamine and methyl vinyl ketone under neat conditions.
 
Publisher AMER CHEMICAL SOC
 
Date 2011-10-13T22:14:11Z
2011-12-15T09:16:16Z
2011-10-13T22:14:11Z
2011-12-15T09:16:16Z
2007
 
Type Review
 
Identifier JOURNAL OF ORGANIC CHEMISTRY,72(22)8202-8215
0022-3263
http://dx.doi.org/10.1021/jo071004q
http://dspace.library.iitb.ac.in/xmlui/handle/10054/13865
http://hdl.handle.net/100/3076
 
Language en