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In this research, we studied about how to apply the
1-(alpha-silyloxy)-cycloalkyl radical intermediate that
was obtained from the radical cyclization of acylsilane.
In our idea, if there is a good leaving group on the
beta-position of the intermediate, then it would be set up
to perform facile beta-scission and finally give a useful
silyl enol ether in a regiospecific manner.
In six-membered ring system, we used sulfonyl group as
alpha-substituent on the acylsilane to decrease the rate of
1,5-hydrogen transfer and to increase the reactivity of
the carbonyl. In the same time, we designed different
kinds of methods in trapping the sulfonyl radical or to
remove sulfinic acid in order to prevent the reaction between
silyl enol ether and sulfinic acid.
To demonstrate the regiospecific nature of this approach for
the preparation of the cyclic silyl enol ether,
we synthesized two kind of cyclic silyl enol ether with methyl
substituent on 3- or 5-position of the ring which can not be
easily prepared from simple cyclic ketone.
We have also developed an efficient approach to synthesize
the alpha-sulfonyl acylsilane from the reaction of simple
acylsilane with N-phenylthio succinimide followed by oxidation.
We believe it is an useful way in the preparation of
alpha-sulfonyl acylsilane.
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