Reaction of Aryl Grignard Reagents with Hexahalobenzenes: Novel Arenes via a Multiple Aryne Sequence

Article abstract of DOI:10.1021/jo00350a018

New methodology for forming four to six new carbon-carbon bonds to an existing benzene ring in a "one-pot" reaction is described.Reaction of hexabromobenzene (7) or 1,2,4,5-tetrabromo-3,6-dichlorobenzene with excess arylmagnesium bromide in THF gives, after aqueous quench, 1,2,4,5-tetraarylbenzenes in good yield (Table I).The actual product is the corresponding di-Grignard 29, formed from a tetrahalo di-Grignard (24, 31) through a sequence of organometallic aryne intermediates (Scheme II).