Lewis acid-catalyzed diastereoselective ene reaction of thioindolinones with bicyclobutanes

02 April 2024, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Bicyclo[1.1.0]butanes (BCBs), featuring two fused cyclopropane rings, have found widespread application in organic synthesis. Their versatile reactivity towards radicals, nucleophiles, cations, and carbenes makes them suitable for various reactions, including ring-opening and annulation strategies. Despite this versatility, their potential as enophiles in an ene reaction remains underexplored. Considering this and given the challenges of achieving diasteroselectivity in ring-opening reactions of BCBs, herein, we present a unique method utilizing BCBs as enophiles in a mild and diastereoselective Sc(OTf)3-catalyzed ene reaction with thioindolinones, delivering 1,3-disubstituted cyclobutane derivatives in high yields and excellent regio- and diastereoselectivity. Notably, structurally different thione derivatives underwent diastereoselective addition to BCBs, affording the corresponding cyclobutanes. The synthesized thioindole-substituted cyclobutanes could serve as a versatile tool for subsequent functional group manipulations.


ene reaction
Lewis acid catalysis
Strain release

Supplementary materials

Supporting Information
Details on experimental procedures, mechanistic experiments, characterization data of all the 1,3-disubstituted cyclobutanes and X-ray data of 8.

Supplementary weblinks


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