1,3-Benzothiazin-4-ones (BTZs) are a promising new class of drugs with activity against Mycobacterium tuberculosis, which have already reached clinical trials. A product obtained in low yield upon treatment of 8-nitro-2-(piperidin-1-yl)-6-(trifluoromethyl)-4H-benzothiazin-4-one with 3-chloroperbenzoic acid, in analogy to a literature report describing the formation of sulfoxide and sulfone derived from BTZ043 [Tiwari et al. (2015). ACS Med. Chem. Lett.
6, 128–133], is a ring-contracted benzisothiazolinone (BIT) 1-oxide, namely, 7-nitro-2-(piperidine-1-carbonyl)-5-(trifluoromethyl)benzo[d]isothiazol-3(2H)-one 1-oxide, C14H12F3N3O5S, as revealed by X-ray crystallography. Single-crystal X-ray analysis of the oxidation product originally assigned as BTZ043 sulfone provides clear evidence that the structure of the purported BTZ043 sulfone is likewise the corresponding BIT 1-oxide, namely, 2-[(S)-2-methyl-1,4-dioxa-8-azaspiro[4.5]decane-8-carbonyl]-7-nitro-5-(trifluoromethyl)benzo[d]isothiazol-3(2H)-one 1-oxide, C17H16F3N3O7S. A possible mechanism for the ring contraction affording the BIT 1-oxides instead of the anticipated constitutionally isomeric BTZ sulfones and antimycobacterial activities thereof are discussed.
1,3-苯并噻嗪-4-酮(BTZs)是一类具有抗结核分枝杆菌活性的新型药物,目前已进入临床试验阶段。在用 3-氯过苯甲酸处理 8-硝基-2-(哌啶-1-基)-6-(三氟甲基)-4H-苯并噻嗪-4-酮时,以低产率获得了一种产物,与文献报告中描述的 BTZ043 形成亚砜和砜的情况类似 [Tiwari et al.ACS Med.Chem.Lett.
6,128-133],经 X 射线晶体学揭示,这是一种环状收缩的苯并异噻唑啉酮(BIT)1-氧化物,即 7-硝基-2-(哌啶-1-羰基)-5-(三氟甲基)苯并[d]异噻唑-3(2H)-酮 1-氧化物,C14H12F3N3O5S。对最初被归类为 BTZ043 砜的氧化产物进行的单晶 X 射线分析清楚地证明,所谓的 BTZ043 砜的结构同样是相应的 BIT 1-氧化物,即 2-[(S)-2-甲基-1,4-二氧杂-8-氮杂螺[4.5]癸烷-8-羰基]-7-硝基-5-(三氟甲基)苯并[d]异噻唑-3(2H)-酮 1-氧化物,C17H16F3N3O7S。本文讨论了环收缩产生 BIT 1-氧化物而非预期的 BTZ 磺酮异构体的可能机制及其抗霉菌活性。