Synthesis, X-ray crystal structures and biological evaluation of some mono- and bi-cyclic 1,3-diazetidin-2-ones: non-natural β-lactam analogues
作者:P. S. Chandrakala、Amy K. Katz、H. L. Carrell、P. R. Sailaja、A. R. Podile、Ashwini Nangia、Gautam R. Desiraju
DOI:10.1039/a802438c
日期:——
Mono- and bi-cyclic 1,3-diazetidin-2-ones (aza-β-lactams) are synthesised and evaluated as non-natural analogues of β-lactams. The aza-β-lactams are designed on the principle that their reaction with active site serine hydroxy will form a carbamoylâenzyme intermediate that is sluggish to hydrolysis. The synthesis of racemic mono- and bi-cyclic aza-β-lactams is carried out starting from pyrimidinone 18 which is transformed to the densely functionalised substrate 20. The chemical reactivity of tricarbonyl 20 for selective functional group manipulation was first assessed and then it was transformed to amino alcohol 24. Cyclisation of 24 affords aza-carbapenams and its homologation followed by aldol cyclisation provides access to aza-carbacephams. The X-ray structures of aza-carbapenam 35 and aza-carbacepham 42 suggest that the structural requirements for biological activity in β-lactams are fulfilled. An unexpected ozonolysis product, phenol 52 resolves spontaneously during crystallisation and its crystal structure was also determined. The biological activity of the novel mono- and bi-cyclic aza-β-lactams was evaluated with potent gram-positive bacterial strain, Bacillus subtilis and compared with β-lactam antibiotics, ampicillin and penicillin G. Of the 19 aza-β-lactams tested, eight compounds show inhibition better than the standards while another eight are of comparable activity. This study shows that aza-β-lactams represent a novel and non-natural lead towards serine peptidase inhibitors.
合成了单环和双环 1,3-二氮杂环丁-2-酮(杂环δ-内酰胺),并将其作为δ-内酰胺的非天然类似物进行评估。杂氮δ-内酰胺的设计原理是,它们与活性位点丝氨酸羟基的反应将形成一种氨基甲酰基酶中间体,这种中间体对水解有抑制作用。外消旋单环和双环氮杂-δ-内酰胺的合成是从嘧啶酮 18 开始的,嘧啶酮 18 转化为功能性很强的底物 20。首先评估了三羰基 20 在选择性官能团操作方面的化学反应活性,然后将其转化为氨基醇 24。对 24 进行环化可得到氮杂碳青霉烯类化合物,对其进行同族反应后再进行醛醇环化可得到氮杂碳青霉烯类化合物。氮杂碳青霉烷 35 和氮杂碳青霉烷 42 的 X 射线结构表明,δ-内酰胺具有生物活性的结构要求已经得到满足。一种意想不到的臭氧分解产物苯酚 52 在结晶过程中自发分解,其晶体结构也已测定。用强效革兰氏阳性细菌菌株枯草芽孢杆菌评估了新型单环和双环偶氮δ-内酰胺的生物活性,并将其与δ-内酰胺类抗生素、氨苄西林和青霉素 G 进行了比较。这项研究表明,氮杂-δ-内酰胺是一种新的非天然丝氨酸肽酶抑制剂。