Handbook of Functionalized Organometallics Applications in S

196
5 Polyfunctional Silicon Organometallics for Organic Synthesis
n-C 7H 15
F
O
O
O
144
146
F
SiMe 3
O
SiMe 3
H
Ts
N
H
Ph
148
SiMe3 MeCHO
Bu 4NF
1) p-MeO-C 6H 4CHO
Bu 4NF, MS4A
THF/hexane, RT
2) HF aq., MeCN
62%
PhCHO
Bu 4NSiPh 3F 2
THF, 40 ºC
60%
n-C7H 15
THF
-40 ºC
F
85% 145
O
O
OH
O
147
O F
OH
C 6H 4-p-OMe
H
Ph
Ts
N
H
OH
Ph
149 (98:2ds)
Scheme 5.37 Fluoride-mediated aldehyde addition of oxiranyl- and aziridinylsilanes.
Me 3Si
150
O
Ph
Ph
TiCl 4
CH 2Cl 2
-78 ºC
79%
151
CHO
OTi
Ph
Ph
OH
Me
O
152
(syn : anti =12:1)
Scheme 5.38 Lewis acid-promoted reaction of cyclopropylmethylsilane with aldehyde.
5.4.3
Synthetic Reactions of Polysilylmethanes
Bis(trimethysilyl)methane derivatives react with aldehydes and ketones in the
presence of a fluoride ion to afford di- and trisubstituted alkenes in one pot [56].
The reaction involves the fluoride-catalyzed carbonyl addition followed by Peterson
elimination. For example, a,a-bis(trimethylsilyl)acetonitrile 153 produces
b-phenylacrylonitrile 154 with high E-selectivity, whereas tris(trimethylsilyl)methane
155 reacts with anisaldehyde at room temperature to give alkenylsilane
156 (Scheme 5.39).
Ph