Clauson–Kaas-Type Synthesis of Pyrrolyl-phenols, from the Hydrochlorides of Aminophenols, in the Presence of Nicotinamide

Abstract

A facile Clauson–Kaas-type pyrrolyl-phenol synthesis has been achieved in the presence of nicotinamide, which is inexpensive and nontoxic. The starting material is aminophenol hydrochloride. This is advantageous in certain cases because it is the only isolatable form of the corresponding aminophenol.

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GRAPHICAL ABSTRACT

Keywords:

• Aminophenol hydrochloride
• Clauson–Kaas
• nicotinamide
• pyrrolyl-phenol

Notes

^a Isolated product 1 after refluxing for 4 h.

^a Isolated product 1 after refluxing for 9 h.

^b Similar yield after 24 h refluxing.

^a Isolated products 2–5 after refluxing for 9 h.

^b From 2a in refluxing acetic acid.

^c From 3a in refluxing acetic acid.

^d In the presence of 4-chloropyridine.