Synthesis 2022; 54(08): 2037-2048
DOI: 10.1055/s-0041-1737326

Palladium-Catalyzed C–H Bond Arylation and O- to N-Alkyl Migratory Rearrangement of 2-Alkoxythiazoles: One-Pot Access to 2-Alkoxy-5-arylthiazoles or 3-Alkyl-5-arylthiazol-2(3H)-ones

Hai-Yun Huang
Haoran Li
Marie Cordier
Henri Doucet
We thank the Centre National de la Recherche Scientifique (CNRS) and the Université de Rennes 1 for financial support. The China Scholarship Council (CSC) is acknowledged for fellowships to H.-Y.H. and H.L.


Pd-catalyzed direct arylation of 2-alkylthiazoles is a well-known reaction affording the corresponding 2-alkyl-5-arylthiazoles in very high yields. Conversely, the reactivity of 2-alkoxythiazoles has not been described yet. Herein, we report conditions for the Pd-catalyzed regioselective C5-arylation of 2-alkoxythiazoles. Moreover, we also found reaction conditions leading to 3-alkyl-5-arylthiazol-2(3H)-ones via a one-pot direct arylation with an O- to N-alkyl migratory rearrangement. The judicious choice of reaction temperature and time allows control over the selectivity of the reaction. In general, at 100 °C, 2-alkoxy-5-arylthiazoles were the major products, whereas, at 120 °C with a longer reaction time, 3-alkyl-5-arylthiazol-2(3H)-ones were obtained with good selectivities. The arylation reaction is promoted by a ligand-free air-stable palladium catalyst and a simple and inexpensive base, without oxidant or further additives, and tolerates a variety of useful substituents on the aryl bromide and also heteroaryl bromides.

Supporting Information

Publication History

Received: 05 October 2021

Accepted after revision: 05 November 2021

Publication Date:
17 January 2022 (online)

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