3,1-Benzothiazin-4-ones and 3,1-Benzoxazin-4-ones: Highly Different Activities in Chymotrypsin Inactivation
摘要:
3,1-Benzothiazin-4-ones are suIfur analogs of the potent serine protease inactivators of the 3, l-benzoxazin-4-one type, which acylate the serine residue within the active site of the enzymes. A series of 2-amino-3,1-benzothiazinones was synthesized, but these compounds showed only very little inhibitory activity toward chymotrypsin, a model serine protease. Detailed investigations revealed that benzothiazinones and benzoxazinones react with identical mechanisms, but benzothiazinones acylate chymotrypsin with much lower rate constants. Investigations of nonenzymatic hydrolysis showed the benzothiazinones to be intrinsically more stable than benzoxazinones. It was concluded from spectroscopic results, that benzoxazinones are highly activated due to the absence of ester-like resonance. 2-Benzoylamino-4H-3,1-benzoxazin-4-one was found to be a new, highly active chymotrypsin inactivator. In contrast, benzothiazinones were found to be resonance stabilized. The contribution of a resonance structure with an exocyclic oxanion to the overall structure of the benzothiazinones and its nonproductive binding to the active site explained their low reactivity toward chymotrypsin. (C) 1995 Academic Press, Inc.
The decarboxylation of isatoicanhydrides with disulfides was realized in the presence of sodium dithionite, leading to S-aryl 2-aminobenzothioate derivatives in moderate to excellent yields. Furthermore, the decarboxylation of diphenyldiselenide with isatoicanhydrides was also examined. It was noted that unexpected 2-(dimethylamino)-4H-benzo[d][1,3]thiazin-4-one was obtained using tetramethylthiuram
在连二亚硫酸钠的存在下,用二硫化物实现了ISA酸酐与二硫化物的脱羧反应,从而以中等至极好的收率得到了S-芳基2-氨基苯甲硫酸酯衍生物。此外,还研究了二苯二硒化物与iSAtoic酸酐的脱羧作用。注意到使用四甲基秋兰姆二硫化物作为硫源获得了出人意料的2-(二甲氨基)-4 H-苯并[ d ] [1,3]噻嗪-4-酮。