Related Experiment Video
Updated: Jun 16, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
A Novel Synthesis of 1,3,5-Trisubstituted Pyrazoles through a Spiro-pyrazoline Intermediate via a Tandem 1,3-Dipolar
Sureshbabu Dadiboyena1, Edward J Valente, Ashton T Hamme
1Department of Chemistry, College of Science, Engineering and Technology, Jackson State University, Jackson, Mississippi 39217 USA.
Abstract:
The syntheses of an important class of hitherto unreported 1,3,5-pyrazoles, inspired by an unanticipated eliminatory ring opening are described. The reported pyrazole compounds were constructed through the Huisgen cyclization of 2-methylene-1,3,3-trimethylindoline and an in situ generated nitrile imine. The newly formed spiro-pyrazoline intermediate presumably then undergoes a ring opening/elimination process to afford a pyrazole, as evidenced by single X-ray crystal data. The current report constitutes the first formal observation of this kind of ring opening involving a spiro-pyrazoline intermediate.
Related Concept Videos
Cycloaddition Reactions: Overview
Nucleophilic Aromatic Substitution: Elimination–Addition
Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
Cycloaddition Reactions: MO Requirements for Thermal Activation
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement

![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)