Iodine Catalysed Synthesis of Luminescent β-Carboline Tethered Thiazolo[4,5-c]carbazole and Naphtho[2,1-d]thiazole Derivatives and Estimation of their Light Emitting Properties

A Simple, convenient and highly efficient I-2-catalysed approach has been unfolded towards the synthesis of highly fluorescent beta-carboline C-1(3)-tethered thiazolo[4,5-c]carbazoles, naphtho[2,1-d]thiazoles and benzothiazole derivatives using Kumujian C as a template. This domino strategy proceeds through assembly of 1-formyl-9H-beta-carbolines, arylamines and elemental sulfur via formation of one C-N and two C-S bonds in a single operation. Importantly, the methodology was found applicable to beta-carboline acetals also. A diversely substituted library of 37 beta-carboline tethered arylthiazole hybrids was prepared in excellent yields. The strategy was found appropriate for gram scale synthesis also. The photophysical properties of these fluorophores were also estimated and showed excellent fluorescence properties with quantum yield (phi(F)) up to 92 %.