Palladium-Catalyzed Stereoselective C-F Bond Vinylation and Allylation of Tetrasubstituted gem-Difluoroalkenes via Stille Coupling: Synthesis of Monofluorinated 1,3- and 1,4-Dienes

Stereodivergent Palladium-Catalyzed C-F Bond Functionalization of gem-Difluoroalkenes

We herein describe a stereodivergent C-F bond functionalization of gem-difluoroalkenes. Using trisubstituted β,β-difluoroacrylates, both E and Z monofluoroalkene products can be obtained with excellent diastereoselectivities. The design of two different reaction manifolds, i.e., Pd(II)- versus Pd(0)-catalyzed cross-coupling of boronic acids, is the key to stereocontrol.

Rhodium(I)-Catalyzed Defluorinative Bisarylation of Monofluorodienes with Boronic Acids

We herein describe a Rh(I)-catalyzed bisarylation reaction of monofluorodienes using arylboronic acids. Two aryl groups are installed in the trisubstituted (E)-alkene products in one step with excellent diastereoselectivities. An intriguing reaction sequence of Rh(I)-catalyzed 1,6-addition followed by defluorinative coupling is proposed for product formation.

Stereoselective Palladium-Catalyzed Hiyama Cross-Coupling Reaction of Tetrasubstituted gem-Difluoroalkenes

We herein describe a diastereoselective Pd(0)-catalyzed Hiyama cross-coupling reaction of gem-difluoroalkenes. The use of organosilicon reagents in this reaction is advantageous over other organometallic reagents by allowing the introduction of a wide range of functional groups, including challenging alkyl groups. Also conveniently, the additive TBAF was not required for (hetero)aryl-substituted difluoroalkenes.

Stereoselective Palladium-Catalyzed C-F Bond Alkenylation of Tetrasubstituted gem-Difluoroalkenes via Mizoroki-Heck Reaction

A highly diastereoselective Pd(0)-catalyzed Mizoroki-Heck reaction of gem-difluoroalkenes is described. Unlike previously reported C-F bond functionalization with organometallic reagents, this reaction takes place between two different alkenes to achieve a formal C-F and C-H bond cross-coupling via a distinct pathway. Monofluorinated 1,3-diene products can be synthesized with control of the geometry of each alkene and good functional group tolerability.

Au(I)-Catalyzed Regioselective Hydrofluorination of Propargylamines Using Aqueous HF

Gold-catalyzed regioselective hydrofluorination of alkynes using aqueous HF has been achieved by employing an amide directing group. For both aryl- and alkyl-substituted propargylamines, the fluorination occurred at the site distal to the amino group.

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

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.

Highly Selective C-F Bond Functionalization of Tetrasubstituted gem-Difluoroalkenes and Trisubstituted Monofluoroalkenes Using Grignard Reagents

We herein describe selective C-F bond functionalizations of tetrasubstituted gem-difluoroalkenes and trisubstituted monofluoroalkenes using Grignard reagents without the transition metal catalyst. β,β-Difluoroacrylates react with Grignard reagents under mild conditions to afford tetrasubstituted (E)-β-monofluoroacrylates. Experimental and computational studies revealed that the selectivity stems from the intrinsic reactivity difference between the (E)- and (Z)-isomers toward excess Grignard reagent, which leads to the resolution of the two products.