Nucleophilic cleavage of 1-oxo-2,8-disubstituted-2,5,8-triaza-1λ5-phosphabicyclo[3.3.0]octanes: a new route to eight- and five-membered heterocyclic systems
作者:Zhengjie He、Susan Laurens、Xavier Y. Mbianda、Agnes M. Modro、Tomasz A. Modro
DOI:10.1039/a903835c
日期:——
8-triaza-1λ5-phosphabicyclo[3.3.0]octanes 1 have been prepared and the nucleophilic cleavage of one of their P–N bonds has been studied. The acid-catalyzed alcoholysis involves in each case the cleavage of the P–N(5) bond, yielding the eight-membered monocyclic diamides 2. In the base-catalyzed reaction, the N(2),N(8)-dialkyl substituted substrates 1 yielded the same products 2, while for the N(2),N(8)-diaryl derivatives
五1-氧代-2,8-二取代的2,5,8-三氮杂- 1λ 5 -phosphabicyclo [3.3.0]辛烷1已经制备和它们的P-N键中的一个的亲核裂解进行了研究。在每种情况下,酸催化的醇解均涉及P–N(5)键的裂解,产生八元单环二酰胺2。在碱催化的反应中,N(2),N(8)-二烷基取代底物1产生相同的产物2,而对于N(2),N(8)-二芳基衍生物,观察到P–N(2)(或P–N(8))键的唯一裂解,得到同分异构体1 ,3,2-二氮杂磷腈产品3。产品2作为N(5)铵盐或N(5)-酰基衍生物,但作为游离碱,它们通过分子内N(5)→P亲核攻击伴随P–N(2)(或P–N(8))键断裂而自发地重排为产物3 。研究了2中N(2)-和N(8)取代基对2→3重排速率以及非对称双取代底物产物分布的影响。产品3的形成的机理通过重排和通过直接1→3的亲核裂解在攻击亲核试剂,磷酰基中心的亲电性的反应性方面所讨论