No abstract

4H-Cromenos e diidropirano[3,2-c]cromenos são obtidos em rendimentos bons a excelentes através de um procedimento simples, brando e eficiente usando poli(N,N´-dibromo-N-etil-benzeno-1,3-dissulfonamida) [PBBS] e N,N,N´,N´-tetrabromobenzeno-1,3-dissulfonamida [TBBDA] como catalisadores. 4H-Chromenes and dihydropyrano[3,2-c]chromenes are obtained in good to excellent yields by a simple, mild and efficient procedure using poly(N,N'-dibromo-N-ethyl-benzene-1,3-disulfonamide) [PBBS] and N,N,N',N'-tetrabromobenzene-1,3-disulfonamide [TBBDA ] as catalysts.

N,N,N',N'-Tetrabromobenzene-1,3-disulfonamide was used as an efficient catalyst for the one-pot synthesis of pyrimidine derivatives in excellent yields from triethoxymethane, ammonium acetate, and various ketone derivatives at 100-110 8C under solvent-free conditions.

A series of 5,7-diaryl-4,7-dihydrotetrazolo [1,5-a]pyrimidines and 5-methyl-7-aryl-4,7-dihydrotetrazolo [1,5-a]pyrimidine-6-carboxylates were obtained from aryl aldehydes, 2-aminotetrazole, substituted acetophenones, or ethyl acetoacetate in good to excellent yields by proceeding through a simple, mild, and efficient procedure utilizing N,N,N,N-tetrabromobenzene-1,3-disulfonamide as catalyst.

A series of pyrimido[1,2‐a]benzimidazoles were obtained from aldehydes, 2‐aminobenzimidazole and ethyl acetoacetate in good‐to‐excellent yields by a simple, mild, and efficient procedure utilizing N,N,N′,N′‐tetrabromobenzene‐1,3‐disulfonamide (TBBDA) and poly(N‐bromo‐N‐ethylbenzene‐1,3‐disulfonamide) (PBBS) as catalysts.