Acid-mediated decarboxylative C-H coupling between arenes and O-allyl carbamates

Treatment of O-allyl N-tosyl carbamates with aromatic compounds in the presence of Cu(OTf)2 or TMSOTf as promoters affords N-substituted 1-arylpropan-2-amines, 1,2-diarylpropanes, 1,1-diarylpropanes, or indanes, depending on the nature of the promoter and of the aryl substrates. A full mechanistic rational allowing appreciation of the outcome of these novel C-H based cascades is proposed. An initial acid promoted decarboxylative/deamidative Friedel-Crafts allylation takes place. After protonation of the allylated arene, evolution of the resulting cation may follow different paths depending on the nature of the arene partner and of the allyl moiety in the carbamate.