Use of Molecular Oxygen as a Reoxidant in the Synthesis of 2‐Substituted Benzothiazoles via Palladium‐Catalyzed CH Functionalization/Intramolecular CS Bond Formation
2010; Wiley; Volume: 352; Issue: 14-15 Linguagem: Inglês
10.1002/adsc.201000604
ISSN1615-4169
AutoresKiyofumi Inamoto, Chisa Hasegawa, Junpei Kawasaki, Kou Hiroya, Takayuki Doi,
Tópico(s)Synthesis and Catalytic Reactions
ResumoAbstract Molecular oxygen (O 2 ) was successfully employed as a reoxidant in cyclizations of thiobenzanilides 1a – s through a palladium‐catalyzed CH functionalization/intramolecular CS bond formation process, leading to an efficient, green method for the synthesis of 2‐arylbenzothiazoles 2a – s . Addition of cesium fluoride (CsF) greatly enhanced the reactions, which produced variously substituted 2‐arylbenzothiazoles with good functional group tolerance. Thioureas 4a – j were also found to be suitable substrates for the cyclization process using a palladium/O 2 catalyst system, thus generating 2‐aminobenzothiazoles 5a – j . One‐pot syntheses of 2‐aminobenzothiazoles 5a – j from aryl isothiocyanates 6 and amines 7 were also successful.
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