The synthesis of sulfur heterocycles via the construction of C–S bonds has received considerable attention due to their biological value and extensive pharmaceutical application. While diverse sulfurating agents have been developed over the past few decades, in this regard, elemental sulfur, with advantages of low toxicity, odorless nature and chemical stability, has great potential for the construction of diverse sulfur heterocycles through its direct incorporation into the target molecules in a concise way. Direct functionalization of inert C–H bonds can shorten the number of reaction steps and minimize the amount of waste formed. Hence, heteroannulations via direct C–H sulfuration is considered to be an attractive strategy for the synthesis of sulfur heterocycles. In the last few years, a vast array of concise systems have been reported for the synthesis of some valuable sulfur heterocycles such as thiophenes, thienoindoles, thienothiazoles, thiazoles, benzothiazoles, and thiadiazoles through direct C–H sulfuration/annulations with elemental sulfur. These are discussed in detail in this review. 1 Introduction 2 Thiophenes 3 Thienoindoles 4 Thienothiazoles 5 Other Fused Thiophenes 6 Thiazoles 7 Benzothiazoles 8 Thiadiazoles 9 Others 10 Summary and Outlook

中文翻译：

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用元素硫直接硫化 C-H 形成含硫杂环的最新进展

通过构建 C-S 键合成硫杂环由于其生物学价值和广泛的药物应用而受到广泛关注。虽然在过去的几十年里已经开发了多种硫化剂，但在这方面，元素硫具有低毒、无味和化学稳定性的优点，通过直接结合到目标分子中，具有构建多种硫杂环的巨大潜力以简洁的方式。惰性 C-H 键的直接官能化可以缩短反应步骤的数量并最大限度地减少形成的废物量。因此，通过直接 C-H 硫化的杂环化被认为是合成硫杂环的有吸引力的策略。在过去的几年中，已经报道了大量简洁的系统，用于通过直接 C-H 硫化/与元素硫成环来合成一些有价值的硫杂环，例如噻吩、噻吩并吲哚、噻吩并噻唑、噻唑、苯并噻唑和噻二唑。这些将在本综述中详细讨论。1 引言 2 噻吩 3 噻吩并吲哚 4 噻吩噻唑 5 其他稠合噻吩 6 噻唑 7 苯并噻唑 8 噻二唑 9 其他 10 总结和展望