Base-enabled access to diastereoselective spirofuran oxindoles and γ-functionalized allenoates
Basavaraja D1, Ajay Krishna M S, Jagadeesh Krishnan
1Chemical Sciences & Technology Division, CSIR-National Institute for Interdisciplinary Science & Technology (NIIST), Thiruvanthapuram-695019, Kerala, India. drsasidharbs@niist.res.in.
Abstract:
Base assisted divergent reactivity of isatins and allenoates has been achieved, which afforded diastereoselective spirofuran oxindoles and γ-functionalized allenoates. The DBU mediated Morita-Baylis-Hillman (MBH) reaction followed by the cascade annulation through the stabilized β-ammonium enolate intermediate led to the spiro-framework, wherein DABCO furnished the γ-functionalized allenoates. The protocol offers access to biologically relevant functionalized oxindole scaffolds with an excellent substrate scope under mild reaction conditions.
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