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Density functional study on the reaction mechanism of palladium‐catalyzed addition of cyanoboranes to alkynes
Author(s) -
Wang M. Y.,
Cheng L.,
Wu Z. J.
Publication year - 2008
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.20944
Subject(s) - intramolecular force , chemistry , alkyne , intermolecular force , dissociation (chemistry) , catalysis , phosphine , reaction mechanism , palladium , density functional theory , ligand (biochemistry) , photochemistry , oxidative addition , computational chemistry , medicinal chemistry , stereochemistry , molecule , organic chemistry , biochemistry , receptor
The B3LYP hybrid density functional method has been carried out to study theoretically the mechanism of Pd(0)‐catalyzed alkyne cyanoboration reaction. Both the intermolecular and intramolecular alkyne cyanoboration reactions were studied. For each reaction, three paths were proposed. In path A of each reaction, the first step is BCN bond oxidative addition to bisphosphine complex Pd(PH 3 ) 2 , in path B of each reaction, the first step is alkyne coordination to bisphosphine complex Pd(PH 3 ) 2 , and in path C of each reaction, the first step is the PH 3 dissociation from Pd(PH 3 ) 2 to form monophosphine complex Pd(PH 3 ). For both reactions, path B is favored. The dissociation and recoordination of phosphine ligand are found to be very important for the entire reaction, in agreement with the experiment. In both intermolecular and intramolecular cyanoboration reactions, cyano migration is preferred to take place compared with alkenylboryl migration for the formation of the final cis products. The rate‐determining step for both intermolecular and intramolecular cyanoboration reactions is found to be the insertion of carbon‐carbon triple bond into PdB bond with the activation energy of 38.4 and 34.3 kcal/mol relative to the initial reactants, respectively. These values suggest that intramolecular reaction is relatively easy to occur. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008