Abstract:
Predominantly, aggressive acid chlorides and stoichiometric coupling
reagents are employed in the acylating process for synthesizing
carbonyl tethered heterocycles. Herein, we report simple acyl
sources, viz. methyl and phenyl esters, which acylate oxindoles via
the mixed Claisen condensation. This straightforward protocol is
mediated by LiHMDS and KOtBu and successfully applied to a wide
range of substrates. It is a noteworthy transformation that skips
the stepwise generation of enolates and acylation, and the reaction
is performed at a moderate temperature with no side reactions.
This protocol produces the first examples of ortho-substituents in
an aryl ring flanked with electron-donating and electron-withdrawing
substrates. Interestingly, robust organometallic ferrocenyl
methyl ester cleaved under these conditions with ease.
Furthermore, biologically important Tenidap’s analog was synthesized
by this protocol.
