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Updated: Jun 4, 2026

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Cascade cyclization, dipolar cycloaddition to bridged tricyclic amines related to the Daphniphyllum alkaloids
Iain Coldham1, Adam J M Burrell, Hélène D S Guerrand
1Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, S3 7HF, UK. i.coldham@sheffield.ac.uk
Abstract:
A tandem one-pot reaction of an aldehyde with a primary amine involving condensation and then cyclization (N-alkylation), followed by intramolecular dipolar cycloaddition of the resulting nitrone or azomethine ylide, provides a synthesis of bridged tricyclic amines. The reaction was most successful using hydroxylamine, and when the dipolarophile was an unsaturated ester, subsequent reduction of the N-O bond and cyclization to the lactam provided the core ring system of the yuzurimine, daphnilactone B, and bukittinggine type Daphniphyllum alkaloids.
Related Concept Videos
Cycloaddition Reactions: Overview
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
Preparation of 1° Amines: Hofmann and Curtius Rearrangement Overview
Cycloaddition Reactions: MO Requirements for Thermal Activation
Nomenclature of Primary Amines

