Metal-free oxidative cyclization for the one-pot synthesis of benzo[d]imidazo[2,1-b]thiazoles from 2-aminobenzothiazoles and cyclic ketones is described. Elemental sulfur combined with molecular oxygen as the benign co-oxidant was found to be unique and highly effective to promote this transformation without the aid of any metal salts. Various cyclic ketones smoothly reacted with 2-aminobenzothiazoles to give functional benzo[d]imidazo[2,1-b]thiazoles in good to very high yields, which thereby demonstrated the synthetic convergence of this methodology.

中文翻译：

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通过元素硫和氧的结合实现2-氨基苯并噻唑和环状酮的无金属氧化环化

描述了用于从2-氨基苯并噻唑和环状酮一锅合成苯并[ d ]咪唑并[ 2,1- b ]噻唑的无金属氧化环化反应。发现元素硫与分子氧结合作为良性助氧化剂是独特的，并且高度有效地促进了这种转变，而无需任何金属盐的帮助。各种环状酮与2-氨基苯并噻唑平稳反应，以高至非常高的收率得到官能化的苯并[ d ]咪唑并[ 2,1- b ]噻唑，从而证明了该方法的合成收敛性。