Selective and Gram-Scale Synthesis of [8]Cycloparaphenylene

Selective and large-scale synthesis of [8]cycloparaphenylene (CPP) was achieved in seven steps starting from commercially available 4-bromo-4′-hydroxybiphenyl and 4,4′-dibromobiphenyl. The key unsymmetrical tetraring unit, 4-bromophenyl and 4′-bromobiphenyl-substituted cis-1,4-bis(triethylsiloxy)-2,5-cyclohexadiene-1,4-diyl (5fA), was synthesized on an ∼50 g scale by stereoselective cis-addition of 4-bromo-4′-lithiobiphenyl to...