A Simple Synthesis of 1-Aminohexa-1,3,5-trienes - the Formation of Stable Conjugated Primary Enamines Under Thermodynamic Control
作者:Michael Riedel、Gerhard Erker
DOI:10.1055/s-1994-25634
日期:——
Pentadienyllithium reacts with nitriles R-CN (R = 2-pyridyl, phenyl, p-tolyl, 2-furyl, 2-thienyl, tert-butyl) to yield the metallated 1-substituted trienamine systems 7a-f (a mixture of 1Z,3E)/(1E,3E)-isomers). Controlled hydrolysis with aqueous ammonia gave the corresponding 1-aminohexa-1,3,5-triene systems 8a-f as a (1Z,3Z)/(1E,3E)-mixture of isomers in 75-85% overall yield. Under thermodynamic control the conjugated primary enamines are much preferred over their ketimine tautomers which could not be detected by 1H NMR spectroscopy at equilibrium conditions.
五二烯锂与腈 R-CN(R = 2-吡啶基、苯基、对甲苯基、2-呋喃基、2-噻吩基、叔丁基)反应,生成金属化的 1-取代三烯胺体系 7a-f(1Z,3E)/(1E,3E)-异构体的混合物)。用氨水进行受控水解,得到相应的 1-氨基六-1,3,5-三烯体系 8a-f,为 (1Z,3Z)/(1E,3E)- 异构体混合物,总产率为 75-85%。 在热力学控制下,共轭伯胺比它们的酮亚胺同系物更受欢迎,后者在平衡条件下无法通过 1H NMR 光谱检测到。