Synthesis of Functionalized Cyclobutenes and Spirocycles via Asymmetric P(III)/P(V) Redox Catalysis

An enantioselective phosphine-catalyzed transformation has been developed for the synthesis of chiral cyclobutene triesters and fluorinated spirocyclic compounds. The strategy involved a P(III)/P(V) redox cycling process, via in situ reduction of phosphine oxide with phenylsilane. This catalytic methodology has enabled the enantioselective synthesis of functionalized cyclobutenes (24 examples, up to 94% ee). On the occasion of the extension of this study to alpha-ketoester indenone substrates, a surprising reactivity has been discovered for the synthesis of spiro-indenone products.

Automated summary

An enantioselective phosphine-catalyzed transformation has been developed for the synthesis of chiral cyclobutene triesters and fluorinated spirocyclic compounds. This catalytic methodology enables the synthesis of functionalized cyclobutenes and surprising reactivity for the synthesis of spiro-indenone products.