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Updated: Jul 15, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Rh(I)-catalyzed bimolecular cyclization between two different 1,5-bisallenes: a combinatorial one-step approach to
1State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China. masm@mail.sioc.ac.cn
Abstract:
In this paper, a bimolecular-cyclization reaction between two different bis(allene)s with at least one heteroatom as the tether under the catalysis of trans-[RhCl(CO)(PPh3)2] is described. This protocol provides an efficient entry to different heterocyclic 18,19-norsteroid-like scaffolds. The tricyclic product was formed highly selectively from the cyclization reaction of bis(2,3-butadienyl)sulfide with dimethyl 2-bis(2',3'-butadienyl)malonate, which sheds light on the mechanism involving the metalla-[4.3.0]-bicyclic intermediate formed by the cyclometallation of the terminal and the internal C=C bonds of each of the two allene moieties in 2-bis(2',3'-butadienyl)malonate.
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