Propargylic Alcohols as Coupling Partners in Transition-Metal-Catalyzed Arene C-H Activation

Transition-metal-catalyzed site selective arene C-H bond activation concomitant functionalization with various coupling partners gain magnificent attraction in synthetic organic chemistry as complementary to traditional transformations. Mechanistically, these C-H functionalization approaches involve directing group assisted concerted metalation-deprotonation (CMD), migratory insertion, and reductive elimination sequences. In this realm, diverse categories of coupling partners were employed as C-H functionalization buddies. Particularly alkynes gain enormous attention as annulating agents. These units coordinates with metalcycle through pi-interaction produce annulation outcomes in a straightforward manner. Very recently, propargylic alcohols were appointed as valuable archetypes in arene C-H activation armoury, as they have shown regio- and chemoselective migratory insertion into primary metalcycle species via hydroxy chelation. The influential regioselectivity was drawn by dual coordination of metal complexes with the pendent directing group and a propargylic hydroxyl group. In this review, we focused on annulations and functionalization of arenes and propargylic alcohols, which afford intricate cycles as well as complex acyclic motifs in a trouble-free manner. We categorized these transformations based on number of atoms of propargylic alcohols involved in annulation along with some addition reactions. We anticipate to pave a way towards enhanced endeavours for discovering novel reaction avenues.