Aspects of structural thiohydroxamate chemistry—on a systematic in the 5-(p-methoxyphenyl)-4-methylthiazole-2(3H)-thione series

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• 作者：Jens Hartung ; Uwe Bergsträ ; ß ; er ; Kristina Daniel ; Nina Schneiders ; Ingrid Svoboda ; Hartmut Fuess
• 关键词：Heterocycle ; Lithium thiohydroxamate ; Pyridinethione ; Steric substituent effect ; Taft– ; Dubois parameter ; Thiazolethione ; Thiohydroxamic acid ; X-ray crystallography
• 刊名：Tetrahedron
• 出版年：2009
• 出版时间：21 March 2009
• 年：2009
• 卷：65
• 期：12
• 页码：2567-2573
• 全文大小：328 K

文摘

Bond angles at thiohydroxamate oxygen in crystal structures of 3-alkoxy-5-(p-methoxyphenyl)-4-methylthiazole-2(3H)-thiones gradually increased with the size of the 3-alkoxy substituent. This effect was attributed to strain on the basis of (i) a linear free energy relationship (Taft–Dubois correlation) and (ii) signal coalescence from resonances of diastereotopic CH₃ groups in solution (O-cumyl substituent; DNMR). Substitution at oxygen along the sequence OR (R=prim-, sec-, and tert-alkyl), OH, and OLi was reflected in a gradual decrease of N,O distances and lengthening of associated C,S bonds. The responsivity for these changes was more pronounced in the thiazole-2(3H)-thione than in the pyridine-2(1H)-thione series.