The use of mechanical ball milling to facilitate the
synthesis
of organic compounds has attracted intense interest from organic chemists.
Herein, we report a new process for the preparation of xanthene and
pyrimidinone compounds by a one-pot method using polymeric aluminum
chloride (PAC), silica gel, and reaction raw materials under mechanical
grinding conditions. During the grinding process, polymeric aluminum
chloride and silica gel were reconstituted in situ to obtain a new
composite catalyst (PAC–silica gel). This catalyst has good
stability (six cycles) and wide applicability (22 substrates). The
Al–O–Si active center formed by in situ grinding recombination
was revealed to be the key to the effective catalytic performance
of the PAC–silica gel composites by the comprehensive analysis
of the catalytic materials before and after use. In addition, the
mechanism of action of the catalyst was verified using density functional
theory, and the synthetic pathway of the xanthene compound was reasonably
speculated with the experimental data. Mechanical ball milling serves
two purposes in this process: not only to induce the self-assembly
of silica and PAC into new composites but also to act as a driving
force for the catalytic reaction to take place. From a practical point
of view, this “one-pot” catalytic method eliminates
the need for a complex preparation process for catalytic materials.
This is a successful example of the application of mechanochemistry
in materials and organic synthesis, offering unlimited possibilities
for the application of inorganic polymer materials in green synthesis
and catalysis promoted by mechanochemistry.