Recent Advances in Alkenyl sp² C–H and C–F Bond Functionalizations: Scope, Mechanism, and Applications

Abstract

Alkenes and their derivatives are featured widely in a variety of natural products, pharmaceuticals, and advanced materials. Significant efforts have been made toward the development of new and practical methods to access this important class of compounds by selectively activating the alkenyl C(sp2)–H bonds in recent years. In this comprehensive review, we describe the state-of-the-art strategies for the direct functionalization of alkenyl sp2 C–H and C–F bonds until June 2022. Moreover, metal-free, photoredox, and electrochemical strategies are also covered. For clarity, this review has been divided into two parts; the first part focuses on currently available alkenyl sp2 C–H functionalization methods using different alkene derivatives as the starting materials, and the second part describes the alkenyl sp2 C–F bond functionalization using easily accessible gem-difluoroalkenes as the starting material. This review includes the scope, limitations, mechanistic studies, stereoselective control (using directing groups as well as metal-migration strategies), and their applications to complex molecule synthesis where appropriate. Overall, this comprehensive review aims to document the considerable advancements, current status, and emerging work by critically summarizing the contributions of researchers working in this fascinating area and is expected to stimulate novel, innovative, and broadly applicable strategies for alkenyl sp2 C–H and C–F bond functionalizations in the coming years.

Cooperativity between the Silver(I) and Iodine(III) Centers in Electrophilic Activation of Organic Substrates

“…Considering this, AgOTf has been chosen as a model noble metal-containing compound, since availability of the triflate-anion excludes anion metathesis upon addition of any of Cat1 OTf -Cat4 OTf and this compound is relatively stable under mild conditions in the presence of oxygen and traces of water, as well as it has many applications in catalysis. [55][56][57][58] Iodolium salt-silver(I) interplay in the solid state. To study possible binding modes between the iodolium salts Cat1 OTf -Cat4 OTf and AgOTf, cocrystals of these species were tried to obtain from MeOH solution.…”

Nickel-Catalyzed Stereoselective Cascade C–F Functionalizations of gem-Difluoroalkenes

“…The selective functionalization of C–F bonds has thus been of long-standing interest in diverse fields of chemistry . Over the past decades, the chemical modification of organic fluorocompounds involving a C–F bond activation has been extensively achieved . However, successively replacing two fluorine atoms from a multifluorinated compound while maintaining high chemoselectivity has scarcely been documented to date.…”

Development of water-based C-X bond formation reactions

“…The earliest known study of a water-based catalyst-free reaction was illustrated by Diels and Alder (1931). 5 They outlined a [4+2] cycloaddition reaction between furan and maleic anhydride by employing water as the solvent for the pericyclic reaction. Under ambient conditions and vigorous mixing, the desired product was obtained.…”

“…H NMR (400 MHz, CDCl 3 ) δ 7.92 (d, J = 7 5. Hz, 2H), 7.54 (t, J = 7.3 Hz, 1H), 7.45 (t, J = 7.6 Hz, 2H), 6.73 (s, 1H), 4.24 (m, 2H), 2.71 (m, 1H), 2.46 -2.31 (m, 3H), 2.12 (s, 3H), 1.99 (m, 2H), 1.28 (t, J = 7.1 Hz, 3H).…”

“…H NMR (400 MHz, CDCl3) δ 7.91 (d, J = 7 5. Hz, 2H), 7.56 (t, J = 7.4 Hz, 1H), 7.47 (t, J = 7.7 Hz, 2H), 6.93 (s, 1H), 2.84 (m, 1H), 2.39 (t, J = 7.7 Hz, 2H), 2.30 (s, 3H), 2.11 -2.07 (m, 1H), 2.06 (s, 3H), 1.91 (m, 2H).…”