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
以聚(N,N'-二
溴-N-乙基-苯-1,3-二磺酰胺)[PBBS]和 N,N,N',N'-四
溴苯-1,3-二磺酰胺[T
BBDA]为催化剂,通过简单、温和、高效的程序获得 4H-色烯和二氢
吡喃并[3,2-c]色烯,收率从良好到极佳