(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.