Physical properties
air stable, colorless liquid; bp 67°C/13 mmHg;
n20
D 1.4184; 1H NMR (CDCl3, 90 MHz) 0.13 (s, 9H), 1.45
(s, 9H), 1.80 (s, 2H); IR 1710 cm?1.
Uses
t-Butyl Trimethylsilylacetate is used to prepare lithium enolates which can be alkylated;can
be alkenated with aldehydes and ketones;can be acylated;can
be reacted with Group 14 halides.
Most applications require initial formation
of the enolate (1) (eq 1), which is obtained as a white solid suspended
in THF, stable indefinitely at ?78°C.
Preparation
an advantage of t-butyl trimethylsilylacetate
over its methyl and ethyl ester analogs is that it can be prepared
by C-silylation of the lithium enolate of t-butyl acetate at
?78°C in THF (85–90% yield). Under the same conditions the
enolates of methyl and ethyl acetate give primarily O-silylated
products.The reagent has also been prepared by a rapid boron
trifluoride etherate catalyzed reaction of trimethylsilylketene
with t-butyl alcohol.
