Recent advances in asymmetric intra- and intermolecular halofunctionalizations of alkenes

Abstract

This review seeks to provide coverage on recent advances in catalytic enantioselective halofunctionalization of alkenes. The aim is to give an overview of various reports, highlighting the new reaction types and strategies developed during the past two years. The scope and challenges of intra- and intermolecular reaction variants are discussed as well.

Stereoselective Chlorination and Bromination of Enamides and Enamines via an Electrostatic Attraction Effect Using (1,1-Diacetoxyiodo)benzene and a Halide Source

“…46 To the best of our knowledge, there have been no such reports with olefin halogenations. [47][48][49][50] The stereoselective halogenation method was extended to the simplification of the synthesis of …”

Intramolecular Hydroalkoxylation of Unactivated Alkenes Using Silane–Iodine Catalytic System

“…19 Very recently, Sarpong and co-workers have reported a TMSI/H 2 O method for hydroamination. 9 In striking contrast to the PhSiH 2 Icatalyzed reaction, they concluded that anhydrous HI is an active species in their catalytic system, and they did not observe any acceleration by the silyl group. To rule out the effect of adventitious water, we examined the hydroalkoxylation of 1a on gram scale under strictly anhydrous conditions [in glovebox, dry CH 2 Cl 2 (water <10 ppm)].…”

Reversing the Regioselectivity of Halofunctionalization Reactions through Cooperative Photoredox and Copper Catalysis

“…[2,5,6] Typically, these proceed through activation of the electrophilic halogen source with a chiral Lewis acid, [7–9] hydrogen bond donor/acceptor, [10–12] or through the formation of a chiral electrophilic halogenating reagent in situ. [13,14] While these reports establish methods that give moderate to excellent stereoselectivity, to our knowledge there are no known methods to reliably alter the inherent regioselectivity of halofunctionalization reactions.…”

“…[2][3][4] Numerous reports of enantioselective variants of traditional halofunctionalization reactions exploit this classic reaction manifold. [2,5,6] Ty pically,such enantioselective transformations proceed through activation of the electrophilic halogen source with achiral Lewis acid [7][8][9] or hydrogen-bond donor/acceptor, [10][11][12] or through the formation of ac hiral electrophilic halogenating reagent in situ. [13,14] Although these reports establish methods that show moderate to excellent stereoselectivity,t oo ur knowledge there are no known methods to reliably alter the inherent regioselectivity of halofunctionalization reactions.W eenvisioned that an alternate method of activating alkenes could lead to the formation of the thermodynamically less favored, and in some cases, traditionally inaccessible regioisomer.P hotoredox catalysis has recently been employed by our research group to activate alkenes through single-electron oxidation.…”