"Front Matter". In: Organosilanes in Radical Chemistry - Index of

102 Addition to Unsaturated Bonds
Table 5.2 Kinetic data for the reaction of Et3Si: radicals with a variety of carbonylcontaining
compounds [49]
Substrate k=M 1 s 1 at 27 8C log A=M 1 s 1 Ea=kJ mol 1
O
O H
3:5 104 8.3 21.3
O
O O
O
O
O
H
Ph Me
O
Ph
Ph
O
O
Ph H
O O
2:8 10 5
O 6:6 10 5
CF 3 CF 2 O CF 2 CF 3
O
Me Me
Me Me
O
1:6 10 6 8.0 10.5
1:2 10 7 7.8 4.2
1:2 10 7 9.4 13.4
3:3 10 8 9.3 4.2
4:1 10 8
5:7 10 8 8.9 0.8
2:5 10 9
5.3.2 HYDROSILYLATION OF CARBONYL GROUPS
The reduction of ketones with silicon hydrides has been occasionally performed
by radical chemistry for a synthetic purpose. The radical adduct is stabilized by
the a-silyloxyl substituent and for R3Si (R ¼ alkyl and/or phenyl) the hydrogen
abstraction from the parent silane is much slower than a primary alkyl radical
(cf. Chapter 3). On the other hand, (TMS) 3SiH undergoes synthetically useful
addition to the carbonyl group and the reactions with dialkyl ketones afford
yields 70 % under standard experimental conditions, i.e., AIBN, 80–85 8C
[45,51]. Reaction (5.25) shows as an example the reduction of 4-tert-butyl-