DIRECT OBSERVATION OF C-O REDUCTIVE ELIMINATION FROM PALLADIUM ARYL ALKOXIDE COMPLEXES TO FORM ARYL ETHERS
DIRECT OBSERVATION OF C-O REDUCTIVE ELIMINATION FROM PALLADIUM ARYL ALKOXIDE COMPLEXES TO FORM ARYL ETHERS
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DOI：
10.1021/ja963324p
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发表时间：
1997-07
影响因子：
15
通讯作者：
R. Widenhoefer;A. Zhong;S. Buchwald
中科院分区：
文献类型：
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作者：
R. Widenhoefer;A. Zhong;S. Buchwald
Reaction of KOCH2CMe3 with [(R)-Tol-BINAP]Pd(p-C6H4CN)Br formed [(R)-Tol-BINAP]Pd(p-C6H4CN)(OCH2CMe3) (5) in quantitative yield (1H NMR spectroscopy). Thermolysis of 5 in THF-d8 at 47 °C led to C−O reductive elimination with formation of p-neopentoxybenzonitrile (85 ± 2%). A secondary P−C bond-cleavage process led to formation of 4,4‘-dimethylbiphenyl (16 ± 2%). Kinetic analysis of the decomposition of 5 at 47 °C in the presence of excess potassium neopentoxide established the two-term rate law, rate = k[5] + k‘[5][KOCH2CMe3], where k = 1.50 ± 0.07 × 10-3 s-1 and k‘ = 6.2 ± 0.4 × 10-3 s-1 M-1, consistent with reductive elimination via competing alkoxide-dependent and alkoxide-independent pathways. In addition, excess KOCH2CMe3 exchanged rapidly with the palladium-bound alkoxide ligand of 5 at 47 °C according to the rate law: rate exchange = kex[5][KOCH2CMe3], where kex = 1.0 ± 0.1 × 102 s-1 M-1. Thermolysis of the related palladium p-cyanophenyl alkoxide complexes (P−P)Pd(p-C6H4CN)(OR) [P−P = (S)-BINAP, ...
