Solventless cyclocondensation of 2-aminothiophenol with thiourea afforded the benzo[]oxazole-2-thiol () capable of existing also in the tautomeric form benzo[]oxazole-2(3)-thione (). Acylation with methyl chloroacetate in dry ethanol in absence of any base or catalyst selectively afforded the -substituted ester 2-(methoxycarbonylmethylthio)benzo[]oxazole () in preference to the corresponding -substituted ester -(methoxycarbonylmethyl)thioxobenzoxazole (). Quantum chemical calculations were conducted to determine the conformational landscape and NBO population analysis showed the strong electronic delocalization resonance interactions on the 2-mercaptobenzaxazole group. The anomeric effect and the occurrence of a 1,4-S···O intramolecular interactions suggest the relevance of chalcogen bonding in the conformational preference. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (33.2%), H⋯O/O⋯H (19.9%) and H⋯C/C⋯H (17.8%) interactions. Hydrogen bonding and van der Waals interactions are the dominant interactions in the crystal packing. Computational chemistry indicates that in the crystal, the C–H⋯O hydrogen-bond energy is 44.8 kJ mol.

中文翻译：

---

作为杂环化合物通用结构单元的苯并恶唑甲酯的合成、构象和赫什菲尔德表面分析


2-氨基苯硫酚与硫脲的无溶剂环缩合得到苯并[]恶唑-2-硫醇()，其也能够以互变异构形式苯并[]恶唑-2(3)-硫酮()存在。在无水乙醇中，在不存在任何碱或催化剂的情况下，用氯乙酸甲酯酰化，选择性地提供取代的酯2-(甲氧基羰基甲硫基)苯并[]恶唑()，优先于相应的取代的酯-(甲氧基羰基甲基)硫代苯并恶唑()。进行量子化学计算以确定构象景观，NBO 群体分析显示 2-巯基苯并恶唑基团上存在强烈的电子离域共振相互作用。异头效应和 1,4-S·O 分子内相互作用的发生表明硫族键合在构象偏好中的相关性。晶体结构的赫什菲尔德表面分析表明，对晶体堆积最重要的贡献来自H⋯H（33.2%）、H⋯O/O⋯H（19.9%）和H⋯C/C⋯H（17.8%） ）相互作用。氢键和范德华相互作用是晶体堆积中的主要相互作用。计算化学表明，晶体中的C-H⋯O氢键能为44.8 kJ mol。