Formal Dehydrative [3+2] Annulation of N‐Arylhydroxamine and Activated Alkyne Toward Indole
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A cascade dehydrative [3+2] annulation reaction of N-substituted arylhydroxylamines and activated alkynes was developed for the synthesis of indole under catalyst-free conditions, water as the the only by-product during this transformation.
Abstract
An efficient approach for the synthesis of indole by the annulation of N-substituted hydroxylamine with activated alkynes under mild reaction conditions was established without the additional catalyst or chemical reagents. Both 3-substituted and 2,3-disubstituted indoles were obtained with good-to-excellent isolated yields by using the terminal and internal electron-deficient alkynes, respectively. This novel and green protocol provides a rapid, mild, and efficient method for the construction of indole heterocycles.
![Formal Dehydrative [3+2] Annulation of N‐Arylhydroxamine and Activated Alkyne Toward Indole](/_next/image?url=%2F_next%2Fstatic%2Fmedia%2Fplaceholder.5ca6fc18.png&w=256&q=75)
![Formal Dehydrative [3+2] Annulation of N‐Arylhydroxamine and Activated Alkyne Toward Indole](/_next/image?url=https%3A%2F%2Fcdn.gdch.de%2Fprod%2Fnadc20264158444_fig_0001_a_36fd5c002c.png&w=256&q=75)
![Formal Dehydrative [3+2] Annulation of N‐Arylhydroxamine and Activated Alkyne Toward Indole](/_next/image?url=https%3A%2F%2Fcdn.gdch.de%2Fprod%2Fnadc20264158499_fig_0001_a_8463b1bf14.png&w=256&q=75)
![Formal Dehydrative [3+2] Annulation of N‐Arylhydroxamine and Activated Alkyne Toward Indole](/_next/image?url=https%3A%2F%2Fcdn.gdch.de%2Fprod%2Fnadc20264158504_gra_0001_a_6653df00f8.png&w=256&q=75)
