(Trimethylsilyl)methyl allylic sulfones in intramolecular 4 + 3 cycloadditions
摘要:
Treatment of (trimethylsilyl)methyl allylic sulfones tethered to a furan with trimethylaluminum results in the formation of products derived from the intramolecular 4 + 3 cycloaddition of the corresponding allylic cations. 2,5-Disubstitution on the furan precludes the formation of cycloadducts and results in two different classes of products which apparently result from ipso or ortho attack of the allylic cation on the furan ring followed by trapping of the resulting oxonium ions by trimethylaluminum.
Photochemical activation of trimethylsilylmethyl allylic sulfones for intramolecular 4+3 cycloaddition
作者:Michael Harmata、Barry F. Herron
DOI:10.1016/s0040-4039(00)73914-1
日期:1993.1
represents the first apparent photochemical generation of acyclic allylic cations for 4+3 cycloadditions. Mechanistically, this process is interpreted as an electron transfer process to form an internal radical cation/radical anion reactive intermediate. This eliminates p-tolylsulfinate anion to form an allylic cation which undergoes an intramolecular 4+3 cycloaddition.