Catalyst Assisted Selective Vinylation and Methylallylation of Quaternary Carbon Centre by using tert-Butyl Acetate

The In(OTf)3-catalyzed α-vinylation of various hydroxy functionalized quaternary carbon centre by using isobutylene generated in situ from tert-butyl acetate is presented as first synthetic methodology. Moreover, tert-butyl acetate is non-flammable feedstock and is a readily available source for the in-situ production of vinyl substituents, demonstrated vinylation reaction with quaternary hydroxy/methoxy compounds. Moreover, an excellent selectivity for the methylallylation over the vinylation was obtained with Ni(OTf)2. In case of peroxyoxindole, methylallyl functionalized 1,4-benzoxazin-3-one derivatives were formed through the sequential rearrangement of peroxyoxindole and the nucleophilic attack by isobutylene. The detailed mechanism for this reaction has been provided based on the preliminary experiments and kinetics studies.