摘要:
The invention describes new spiro[chroman-2,2'-indole] derivatives of formula (I). When compounds of the invention, 1',3',3,4-tetrahydrospiro[chromen-2,2'-indoles], are treated with solution containing cyanide ions, 3,4-dihydropyrane ring opening occurs, resulting in formation of colored 4-nitrophenolate ion, which is detectable colorimetrically.