We have detailed mild and operationally simple reaction conditions to achieve tert-alkylations of aromatic systems with tertiary alkylperoxides and alcohols in forming all-carbon quaternary centers through synergistic Brønsted/Lewis acid catalysis. These reactions fill a gap in the Friedel-Crafts alkylation literature by enabling the use of tertiary aliphatic alcohols that lack stabilizing aryl, alkenyl, and alkynyl substituents. We expect this approach will prove to be practical in installing quaternary carbon centers when orchestrated into synthesis plans that take advantage of C-O bonds (e.g., triflyl and methoxy groups) for cross-coupling applications. The use of cost-effective and readily-available iron, alcohol and arene reagents render this methodology advantageous for all-carbon quaternary center and C(sp 2 )-C(sp 3 ) bond synthesis.