Halochromic Molecules. Synthesis of Substituted 6H‐Chromeno[4,3‐b]indolizines and their Aza‐analoguesWe have synthesized a series of substituted chromeno[4,3‐b]indolizines and their respective aza‐analogues. Dyes generated from them contain the electrondonating 2‐(2‐hydroxy‐5‐methylphenyl)indolizin‐3‐yl moiety. The 90 MHz FT1H‐NMR spectra of starting and final products supported the postulated structures. Fragmentations in the mass spectra also were consistent with