Efficient synthesis of benzo(hetero)aryl-5-yl(2-hydroxyphenyl)methanones <i>via</i> mechanochemical benzannulation

A new mechanochemical approach to novel benzo(hetero)aryl-5-yl(2-hydroxyphenyl)methanones is disclosed. The advantages of this approach include its avoidance of potentially harmful organic solvents, relatively short reaction times, and relatively simple operational handling. Upon sp³ C-H activation, unprecedented benzannulations of 2-methylbenzaldehyde and 2-methylindole-3-carbaldehyde with 3-formylchromones were successfully achieved, accompanied by significantly reduced E-factors. Products from our reactions are very useful and have the potential to be readily transformed into sophisticated multicyclic molecules and chemical auxiliaries.