Polyoxometalate Catalysis under Alkaline Conditions: Self-Assembly of Lanthanum Ion-Doped Steady Polyoxophosphitemolybdates for Quinazoline Synthesis.

The convenient and effective catalytic synthesis of quinazolines holds considerable significance due to their high economic value, and designing a cluster-type alkali-resisting catalyst such as polyoxometalates (POMs) still poses a significant challenge. Herein, three lanthanum ion-doped steady polyoxophosphitemolybdates with the formulas of [CHNH]{La(HO)Na[MoO(OH)(HPO)]}·10HO (), [CHNH]{La(HO)[MoO(OH)(HPO)]}·8HO (), and [CHNH]{La(HO)Na[MoO(OH)(HPO) (PO)]}·16HO () were synthesized by using HPO as the template. Structural analysis revealed that forms a three-dimensional structure through the connection of La with an hourglass-shaped {Na[PMoO]} unit. forms a three-dimensional structure with a porous channel and the same {PMoO} building block. When the synthetic microenvironment was adjusted by changing the type of reducing agent, some of the hypophosphite in the building units was oxidized, thereby altering the structure, and compound was formed. All compounds are alkali-resistant and catalytically active toward the conversion of 2-aminobenzyl alcohol and benzonitrile into 2-phenylquinazoline, and achieves the best yield of 91.7%, which is much better than those of classic Keggin and inorganic CaMoO, indicating the synergistic catalytic effect of Mo and La centers. Also, compound exhibits good activity and reliability in catalyzing reactions of the same type with different substrates.