A pinboard by
Deepti Kalsi

Graduate Student, Indian Institute Of Technology Kanpur


C-H bond funtionalization utilizing first row transition metals like cobalt catalyst.

Functionalization of unreactive C-H bonds into selective C-C or C-X bonds not only simplify the synthesis of pharmaceuticals, natural products, but also sustainable. In this regard, catalyst based on noble metals like Rh, Ir, Pd has attained its pinnacle over the past few years for a vast number of synthetic transformations through C−H bond functionalization. But, due to its meagre resources and its extortionate prices, however, we need an alternative for bringing our research to a more pragmatic or industrial level. As a result, the use of inexpensive first-row transition-metal catalysts for sustainable C−C or C-X transformations has gained considerable recent momentum. In this context, rather environmentally benign cobalt complexes bear great potential for applications in homogeneous catalysis. Cobalt possess variable oxidation state hence it is expected to have better catalytic activity and unique reactivity. To find its interesting mode of action and I explore during my thesis to study C-H bond functionalization using air stable, low cost, versatile cobalt (III) catalyst. To begin with I have chosen functional groups such as sulphonamide which are common motifs in many drugs and medicinal compounds and play a significant role in their bioactivity. We reported cobalt catalyzed C-H bond annulation of sulfonamide via C−H and N−H activation with terminal and internal alkynes.In continuation, we have also reported C–H and N–H Bond Annulation of Benzamides with Isonitriles Catalyzed by Cobalt(III) under mild conditions. Hence, we have shown atom economical sustainable insertion of isonitrile to C-H and N-H bond of benzamide using green solvent such as CPME. Moving from concept of utilizing chelation assisted directing group concept of chelation assisted directing group to traceless directing group stratergy. At times, it was difficult to remove the cheation assisted directing group after fucntionalization. Therefore, we examined reactivity of CpCo(III) where the potential for exploiting its unique reactivity is still great using weakly chelating/traceless directing groups. We have shown an unprecedented C(8)-H bond allylation of quinoline with allyl carbonate and allyl alcohol catalyzed by CpCo(III) using a quinoline-N-oxides as substrates.Further understanding of reaction mechanism and exploration of new reaction through activation of unreactive C-H bonds are currently progress in my doctoral studies.