Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 6. Pyrolysis of substituted cinnamoyl ylides as a route to conjugated enynes
作者:R. Alan Aitken、Christine Boeters、John J. Morrison
DOI:10.1039/p19940002473
日期:——
The substituted cinnamoyl ylides 6 and 7, readily prepared in one step from the quaternary phosphonium salts 8 and cinnamoyl chlorides 9, undergo extrusion of Ph3PO upon FVP to give the 1,3-enynes 12 and 13 in moderate yield. At 500 °C there is little double bond isomerisation, but at 700 °C this does occur to give almost 1:1 mixtures of E and Z isomers. In a few cases, including those with a nitrophenyl
由季phospho盐8和肉桂酰氯9一步制备的取代肉桂酸酯基化物6和7在FVP上经过Ph 3 PO挤出,以中等收率得到1,3-烯炔12和13。在500°C下几乎没有双键异构化,但是在700°C时确实发生了几乎1:1的E和Z混合物异构体。在少数情况下,包括存在硝基苯基的情况,收率很低或反应完全失败。通过使用酯稳定的内酯来改善1-苯基丁烯的不良产率的尝试仅部分成功,因为失去酯基所需的苛刻条件导致明显的异构化为萘。报告了20个炔的完全归属的13 C NMR光谱。已经制备了一个异构体β,γ-不饱和-δ-氧代酰化物的例子,14,发现在700°C下FVP上的Ph 3 P损失,从而以低收率得到了茚和苯。