1,1,3,3-tetramethyl-2-methyleneindan derivatives: Syntheses with imminent rearrangement

Article abstract of DOI:10.1016/S0040-4020(01)81904-9

The syntheses of 2,2,3,3-tetramethyl-1-indanylidene and of 1,1,3,3-tetramethyl-2-indanylidene derivatives from 1,1,3,3-tetramethyl-2-indanone are reported. Access to the second series is restricted by the ease of methyl migration under carbenium-like conditions, such as electrophilic bromination. The rearrangement products are described and also the methods avoiding their formation. Nucleophilic bromination of the oxirane 19 allows to efficiently prepare the sterically shielded bromoalkene 21 (Section B) or the enol acetate 34 (Section C) and other key compounds for further transformations.