Synthesis of Quinone Methide Substituted Neonicotinoid
Derivatives via 1,6-Conjugate Addition of <i>N</i>‑Benzyl
Nitro Ketene Aminals with <i>para</i>-Quinone Methides Accompanying
Oxidation
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Abstract
A concise and efficient route for
the synthesis of quinone methide
substituted neonicotinoid derivatives (<b>4</b>–<b>5</b>) via the one-pot Cs<sub>2</sub>CO<sub>3</sub>-catalyzed
1,6-conjugate addition of <i>N</i>-benzyl nitro ketene amines
(<b>2</b>) or 1,1-enediamines (<b>3</b>) with <i>para</i>-quinone methides (<b>1</b>) in acetone and an
oxidation reaction using atmospheric oxygen has been developed. This
protocol represents a route to obtain a novel class of quinone methide
substituted neonicotinoid derivatives in a concise, rapid, and practical
manner. This reaction is particularly attractive because of the following
features: low-cost and biocompatible solvent, mild temperature, atomic
economy, high yields, and potential biological activity of the product