Transition metal catalyzed [2+2+2] cycloaddition reactions for the synthesis of N-ARYL-, 1-(2-Pyridyl)-, 3-(2- Thiopyridyl) indoles

Abstract

Introduction N-Aryl-, 1-(2-pyridyl)- and 3-(2-thiopyridyl)indoles are ubiquitously found in various pharmaceuticals, agrochemicals as shown in figure 1. Over the past decades, transition metal catalyzed C-H activation reactions, metal-free cascade reactions or cross coupling reactions have been generally employed for their synthesis. Due to the importance of these bioactive molecules, organic chemists are involved in development of efficient, economical and short routes for their synthesis from long time. However, the greatest challenge in synthetic chemistry is the development of a new methodology that can efficiently furnish target products without creating by-product(s). Therefore, our aim was to develop new methodologies that can efficiently afford our target compounds [N-Aryl-, 1-(2-pyridyl)-, 3-(2- thiopyridyl)indoles] without creating any by-product(s) under mild reaction conditions and one such class of reactions are [2+2+2] cycloadditions. Finally, we have developed transition metal catalyzed [2+2+2] cycloaddition reaction for the construction of various N-aryl-, 1-(2-pyridyl)-, 3- (2-thiopyridyl)indoles moieties.