Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 3. Preparation of o-methoxyphenyl- and o-methylsulfanylphenyl-alkynes and their cyclisation to benzofurans and benzothiophenes
作者:R. Alan Aitken、Graham Burns
DOI:10.1039/p19940002455
日期:——
loss of Me· and cyclisation of the resulting radicals to afford 2-substituted benzofurans or benzothiophenes 17–24. Where the substituent R1 on the ylidic carbon of the starting material is phenyl, this is incorporated unchanged into the heterocyclic products. Where R1 is Et or Pri the vinyl products are formed by intramolecular abstraction of a β-hydrogen atom following cyclisation. For R1= Me, Pr
十四新β氧代磷叶立德1 - 14轴承ö甲氧基苯甲酰基或ø - (甲基硫烷基)苯甲酰基已经制备和它们的热分解行为的研究。而闪光真空热解(FVP)在700℃下使约pH的挤出3 PO,得到预期炔16,这是伴随着在850℃下通过我的损失·所得的基团的和环化,得到2-取代的苯并呋喃或苯并噻吩17 – 24。在起始原料的芳基碳上的取代基R 1是苯基的情况下,其未改变地并入杂环产物中。其中R 1为Et或Pr我乙烯基产品由下列环化β氢原子的分子内抽象形成。对于R 1= Me,Pr,Bu和C 5 H 11,环化之后是从烷基中夺取氢原子,导致其断裂并产生具有2-甲基,乙基和乙烯基取代基的产物。在这些情况下,可以通过自由基链反应解释产物,该自由基链反应涉及在饱和碳原子上碳原子的不寻常的均质取代。