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B(C6F5)3 catalyzed hydrosilation of enones and silyl enol ethers
被引:146
作者:
Blackwell, JM
[1
]
Morrison, DJ
[1
]
Piers, WE
[1
]
机构:
[1] Univ Calgary, Dept Chem, Calgary, AB T2N 1N4, Canada
来源:
基金:
加拿大自然科学与工程研究理事会;
关键词:
Lewis acid catalysis;
hydrosilation;
enones;
silylenol ethers;
tris-(pentafluorophenyl)borane;
D O I:
10.1016/S0040-4020(02)00974-2
中图分类号:
O62 [有机化学];
学科分类号:
070303 ;
081704 ;
摘要:
The 1,4 hydrosilation of a variety of simple alpha,beta-unsaturated enones as catalyzed by B(C6F5)(3) (1-2%) is described. For substrates with no steric hindrance near the beta-carbon, 1,4 addition of silane is very clean; in other instances, 1,2 hydrosilation is competitive. The reaction is facile with five commercially available silane reagents. For two examples, a novel hydrosilation of the resulting silylenol ethers was also observed. The net trans stereochemistry of H-Si addition to the silylenol ether C=C bond was established and points to a stepwise mechanism for this reaction. This was supported by the observation and full spectroscopic characterization of a silylcarboxonium ion intermediate with an [HB(C6F5)(3)](-) counteranion in the hydrosilation of the silylenol ether derived from 4,4-dimethyl-2-cyclohexen-1-one and PhMe2SiH. (C) 2002 Elsevier Science Ltd. All rights reserved.
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页码:8247 / 8254
页数:8
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