A novel sandwich-type thorium-substituted phosphotungstate, H2N(CH3)210Th(PW11O39)2·24H2O (ThP2W22) was successfully synthesized and characterized, which is constructed from two mono-lacunary Keggin-type PW11O397- units bridged by an eight-coordinate Th4+ ion. ThP2W22 demonstrates exceptional catalytic activity as a Lewis acid catalyst in the synthesis of 2,3-dihydroquinazolinones via cyclization of 2-aminobenzamides with aldehydes. Various quinazolinones were synthesized in excellent yield (75%-92%) under mild and green reaction conditions. Control experiments confirm the synergistic role of Th4+ and the polyoxometalate framework in enhancing catalytic efficiency, highlighting thorium-containing polyoxometalate as a promising catalyst in heterocycle synthesis.
Chen et al. (Sun,) studied this question.