Ring expansions of N-methyl-1,2,5-oxadiazolium and 1,2,3-triazolium perchlorate salts with bases to six-membered azines: direct detection of an addition intermediate in an addition–elimination mechanism and a degradation of 1,2,5-oxadiazolium salts to α-cyano nitrones
作者:Richard N. Butler、Elaine C. McKenna、John M. McMahon、Karen M. Daly、Desmond Cunningham、Patrick McArdle
DOI:10.1039/a701233k
日期:——
α-cyano nitrones via a ring degradation which competes with ring expansion. The reactions with KOBut and LiNPri2 do not involve an addition of the base to the azolium salt. Reactions have been monitored by 13C NMR spectroscopy by using 13CN–. An X-ray crystal structure is reported for (E)-N-(α-cyanobenzylidene)methylamine N-oxide.
2-甲基-1,2,5-恶二唑高氯酸盐和1-甲基-2-芳基-1,2,3-三重氮高氯酸盐与碱KCN,NaOEt,KOBu t和LiNPr i 2的反应使环扩展为取代的1,2,5-恶二嗪和1,2,4-三嗪 以氰化物为基础,反应遵循加成消除途径,在两种情况下,加成中间体已被分离或通过低温NMR光谱法直接检测到。含有氰化物的恶二唑鎓体系还通过与环扩环竞争的环降解,为α-氰基硝酮提供了一条有用的新途径。与KOBu t和LiNPr i 2的反应不需要将碱加到偶氮盐中。通过使用13 CN –进行13 C NMR光谱监测反应。报告了(E)-N-(α-氰基亚苄基)甲胺N-氧化物的X射线晶体结构。