Synthesis of photochromic spiroindolinopyrans with extended conjugation
Unsaturated side chains have been introduced in benzopyran site of parent indolinospiropyran moiety using Wittig reaction under conditions of Phase Transfer Catalysis in a one pot synthesis. The resultant unsaturated photochromic indolinospirobenzopyrans show significant bathochromic shift in the uv region of absorption spectra.