Allenyl allylic ethers: synthesis and thermal rearrangements
摘要:
Application of the sequence halogenation/dehydrohalogenation/isomerization to alkenes 1a-g affords allenyl allylic ethers 5a-g. Thermal isomerizations of 5a,d,e proceed by Claisen rearrangement, while 5b,c,f,g are transformed by alternate modes of [2 + 2]cycloaddition involving biradical intermediates of type 19 to polycyclic structures; the variations in these thermal isomerizations are mainly a function of ring size.
Thermal isomerizations of allenyl cycloalken-3-yl ethers
作者:Jean-Pierre Dulcere、Jack K. Crandall
DOI:10.1039/c39900000561
日期:——
Thermalisomerization of allenylether (1b) proceeds by intramolecular [2 + 2] cycloaddition to give (4), whereas the higher homologue (1c) is transformed by an alternate mode of [2 + 2] cycloaddition to the unstable alkene(7), which spontaneously dimerizes to (8) and (9); X-ray determinations confirm the structures of (8), (9), and lactone (6) derived from (4).