4-Azapteridines.<b>2</b>. spectral, chromatographic, and X-Ray crystallographic studies concerning the mode of covalent addition to the pyrazino[2,3-<i>e</i>]-<i>as</i>-triazine ring system
作者:Cherng-Chyi Tzeng、Urszula Rychlewska、Derek J. Hodgson、Raymond P. Panzica
DOI:10.1002/jhet.5570230108
日期:1986.1
compounds are obtained. Initially, cyclization of the ortho-diamino-as-triazines with glyoxal proceeds in a stereoselective manner giving rise to both the cis and trans adducts. A single-crystal X-ray diffraction study has determined the predominant and most stable adduct to be the trans (R,R or S,S) isomer. Spectroscopy (nmr) has verified the intermediacy of the cis adduct, but because of the aforementioned
未知吡嗪并[2,3- e ]-为-三嗪环系统的第一个例子,即6,7-二羟基-5,6,7,8-四氢吡嗪并[2,3 - e ]-为-通过将选定的5,6-二氨基-作为-三嗪与40%的乙二醛水溶液闭环来制备三嗪。这些4-氮杂环丁烷在C(7)位置经历与醇的新型交换过程。当溶于醇中并在室温下搅拌时,形成并分离出7-烷氧基,6-羟基类似物。实际上,在闭环过程中,如果将醇用作溶剂,则仅获得后者的化合物。最初,邻位-二氨基-环化为带有乙二醛的β-三嗪以立体选择性方式进行,同时产生顺式和反式加合物。单晶X射线衍射研究已确定主要和最稳定的加合物是反式(R,R或S,S)异构体。光谱法(nmr)证实了顺式加合物的中间体,但是由于上述交换过程,仅反式异构体被分离出来。这些σ加合物的交换位点已严格确定为C(7)。提出了发生这种交换过程的可能的反应机理。