Related Experiment Video
Updated: Aug 7, 2026

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides
Published on: May 26, 2019
1,3-Dipolar character of 2-vinyl quinazoline 3-oxides; first and second generation cycloaddition products
Frances Heaney1, Elaine Lawless, Mary Mahon
1Department of Chemistry, National University of Ireland, Maynooth, Ireland.
Abstract:
The reaction between the heteroaromatic N-oxides 1a, 1b and 1c with dimethyl acetylenedicarboxylate or methyl propiolate furnishes 1,3-benzodiazepines, the products of ring transformations of primarily formed cycloadducts. The structures of 8a and 10a have been confirmed by X-ray crystallographic analysis. The aldonitrone 1c also reacts with N-methylmaleimide and with phenyl vinyl sulfone to furnish the first examples of primary cycloaddition products from quinazoline 3-oxides.
Related Concept Videos
Cycloaddition Reactions: MO Requirements for Thermal Activation
Cycloaddition Reactions: Overview
Electrophilic 1,2- and 1,4-Addition of X2 to 1,3-Butadiene
Conjugate Addition (1,4-Addition) vs Direct Addition (1,2-Addition)
Conjugate addition results in a thermodynamically stable product. The reaction retains the stronger C=O bond at the expense of the weaker C=C π bond. The process is slow as the β carbon is less electrophilic than the carbonyl carbon.
Direct addition products are formed faster owing to...
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Thermal and Photochemical Electrocyclic Reactions: Overview

