TY - JOUR
T1 - Computationally Assisted Mechanistic Investigation into Hypervalent Iodine Catalysis
T2 - Cyclization of N-Allylbenzamide
AU - Butt, Smaher
AU - Das, Mirdyul
AU - Sotiropoulos, Jean-Marc
AU - Moran, Wesley
PY - 2019/12/6
Y1 - 2019/12/6
N2 - Previous experimental work identified 2-iodoanisole as the best precatalyst for the oxidative cyclization of N-alkenylamides into 2-oxazolines. Herein, we describe our investigation into the effect on the reaction rate based on the structure of the iodoarene precatalyst. We also reveal the mechanism of the cyclization based on DFT modeling and obtain a clear correlation between observed reaction rates and computationally derived activation energies for different iodoarenes. In addition, the rate-limiting step is shown to be the cyclization of the substrate that is zero order in the concentration of the iodoarene precatalyst. The rate of cyclization is found to correlate with the ease of oxidation of the iodoarene; however, the most easily oxidized iodoarenes generate iodine(III) species that decompose readily. Finally, loss of iodoarene from the cyclized intermediate can proceed by either ligand-coupling or S
N2 displacement (reductive elimination), and this is shown to be substrate-dependent.
AB - Previous experimental work identified 2-iodoanisole as the best precatalyst for the oxidative cyclization of N-alkenylamides into 2-oxazolines. Herein, we describe our investigation into the effect on the reaction rate based on the structure of the iodoarene precatalyst. We also reveal the mechanism of the cyclization based on DFT modeling and obtain a clear correlation between observed reaction rates and computationally derived activation energies for different iodoarenes. In addition, the rate-limiting step is shown to be the cyclization of the substrate that is zero order in the concentration of the iodoarene precatalyst. The rate of cyclization is found to correlate with the ease of oxidation of the iodoarene; however, the most easily oxidized iodoarenes generate iodine(III) species that decompose readily. Finally, loss of iodoarene from the cyclized intermediate can proceed by either ligand-coupling or S
N2 displacement (reductive elimination), and this is shown to be substrate-dependent.
KW - Activation energy
KW - Ligands
KW - Reaction rates
UR - http://www.scopus.com/inward/record.url?scp=85075173930&partnerID=8YFLogxK
U2 - 10.1021/acs.joc.9b02623
DO - 10.1021/acs.joc.9b02623
M3 - Article
VL - 84
SP - 15605
EP - 15613
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
SN - 0022-3263
IS - 23
ER -