Herein, we report an efficient and chemoselective method for
the generation of β-ketophosphonates based on the Claisen
condensation of the lithiated α-(trimethylsilyl)methylphosphonate
with activated esters (Scheme 1, eq 3). By taking
advantage of the α-effect of the silicon
14
and the steric
hindrance of the trimethylsilyl group, the reactivity of such
phosphonate reagents could be modulated, thereby increasing
the chemoselectivity and functional group tolerance in the
substrates. α-(Trialkylsilyl)phosphonates have been extensively
studied by Savignac et al.
15
and are mainly used as precursors of
vinylphosphonates through the Peterson olefination.
ever, to the best of our knowledge, only two reports were
dealing with the use of those reagents for the synthesis of
‑substituted β‑ketophosphonates.
17,18
In one report, the
conjugate addition of organolithium reagents to diethyl
16
How-