TY - JOUR
T1 - Role of base assisted proton transfer in N-heterocyclic carbene-catalyzed intermolecular Stetter reaction
AU - Ajitha, Manjaly J.
AU - Suresh, Cherumuttathu H.
N1 - Funding Information:
We thank the support from the Council of Scientific and Industrial Research (CSIR), Government of India through the project CSC0129 . A.M.J. is thankful to UGC, Government of India for a fellowship.
PY - 2013/12/25
Y1 - 2013/12/25
N2 - The mechanism of the NHC-catalyzed intermolecular Stetter reaction between benzaldehyde and cyclopropene has been investigated using the PCM-M062X/6-311++G(3df,2p)//M062X/6-31+G(d,p) level of DFT. Compared to the direct reaction, a substantial reduction in the activation free energy by 10.6-14.4 kcal/mol is observed when the reaction is performed in the presence of water, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), and 1,8-diazabicyclo[5.4.0] undec-7-ene (DBU). The bases promote the proton transfer step of the reaction to yield the Breslow intermediate. An early concerted transition state has been located for the stereocontrolling C-C bond formation step (ΔG# = 26.6 kcal/mol) which is used to explain the diastereomeric ratio observed in the experiment.
AB - The mechanism of the NHC-catalyzed intermolecular Stetter reaction between benzaldehyde and cyclopropene has been investigated using the PCM-M062X/6-311++G(3df,2p)//M062X/6-31+G(d,p) level of DFT. Compared to the direct reaction, a substantial reduction in the activation free energy by 10.6-14.4 kcal/mol is observed when the reaction is performed in the presence of water, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), and 1,8-diazabicyclo[5.4.0] undec-7-ene (DBU). The bases promote the proton transfer step of the reaction to yield the Breslow intermediate. An early concerted transition state has been located for the stereocontrolling C-C bond formation step (ΔG# = 26.6 kcal/mol) which is used to explain the diastereomeric ratio observed in the experiment.
KW - Breslow intermediate
KW - Density functional theory
KW - N-Heterocyclic carbene
KW - Organocatalysis
KW - Stetter reaction
UR - http://www.scopus.com/inward/record.url?scp=84888134754&partnerID=8YFLogxK
U2 - 10.1016/j.tetlet.2013.10.116
DO - 10.1016/j.tetlet.2013.10.116
M3 - Article
AN - SCOPUS:84888134754
SN - 0040-4039
VL - 54
SP - 7144
EP - 7146
JO - Tetrahedron Letters
JF - Tetrahedron Letters
IS - 52
ER -