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Updated: Aug 14, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Sequential intermediates in the base-catalyzed conversion of bis(pi-conjugated propargyl) sulfones to
Yossi Zafrani1, Hugo E Gottlieb, Milon Sprecher
1Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel.
Abstract:
[reaction: see text] In a recent article, we reported on the base-catalyzed rearrangements of dipropargyl selenides, -sulfides, -sulfoxides, and -sulfones that eventually lead to polycyclic aromatic products. In the present work, we report on the first isolation and characterization of the thiophene dioxide intermediates 5b,c from a mild tandem isomerization/cyclization/aromatization of bis(pi-conjugated propargyl) sulfones. Monoallene 2b,c and diallene 3b intermediates were also identified by NMR. A kinetic study of the rearrangement of 1a-c revealed that the unusual facile tandem process is highly dependent on the nature of gamma-substitution.
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