Green Approach Toward One Pot Cascade Synthesis of 3-Aryl-3,4-Dihydro-1,2,4 Benzothiadiazine-1,1-Dioxides
A silica-gel-supported ceric ammonium nitrate (CAN-SiO2) was found to be an effective catalyst for the cascade synthesis of functionalized 3-aryl-3,4-dihydro-1,2,4-benzo- thiadiazine-1,1-dioxides using 2-aminobenzenesulfonamide and benzaldehydes at room temperature. The reaction allows rapid cyclization (10−70 min) with 5 mol% CAN impregnated on silica gel to give the desired products in excellent yield without further column purification. The protocol uses inexpensive and environmentally friendly CAN-SiO2as the catalyst, and no ligand or additive was required.
[Supplementary materials are available for this article. Go to the publisher's online edition ofPhosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional figures]