Asymmetric Hydroarylation Reactions Catalyzed by Transition Metals: Last 10 Years in a Mini Review

Abstract

Hydroarylation reactions play a pivotal role in organic chemistry due to their versatility and efficiency. In the last 10 years, the scientific production around this reaction has been very high, but in its asymmetric version, the results are less. In this mini review, selected literature examples are considered to draw attention to directions of the asymmetric hydroarylation reaction mediated by transition metal catalysts. The selected works were grouped in two main sections. In the first, we reported examples relating the narrower definition of hydroarylation, namely the metal-catalyzed processes where inactivated aryl moiety undergoes a direct functionalization via insertion of an unsaturated compound. In the second part, hydroarylation reactions take place with the use of pre-activated aryl substrates, usually aryl-iodides or aryl-boronated.

Ir-Catalyzed Asymmetric Hydroarylation of Alkynes for the Synthesis of Axially Chiral Heterobiaryls

“…Despite the progress made in this field, however, most of the alkyne hydroarylation reactions reported for the asymmetric synthesis of axially, helically, or planar chiral compounds are nondirected intramolecular Friedel–Crafts-type alkenylations that proceed via the formation of metal π-alkyne complexes (Scheme B). Compared with the better-established methodologies for the asymmetric hydroarylation of vinyl ethers, 1,3-dienes, alkenes, or bicycloalkenes, the hydroarylation of alkynes represents a more challenging problem, particularly in controlling regioselectivity. Directing group-assisted intermolecular versions have been scarcely explored: only very recently Hou and Luo et al described the only successful example of such a strategy, namely, the asymmetric N -directed C–H alkenylation of ferrocenes using half-sandwich chiral Sc complexes as the catalysts (Scheme C), which gives access to a new family of chiral planar nitrogen-olefin ligands with potential applicability in asymmetric catalysis .…”

Pd(ii)-catalyzed hydroarylations/hydroalkenylations of terminal alkynes: regioselective synthesis of allylic, homoallylic, and 1,3-diene systems

“…3 In recent years, hydroarylation of alkynes has gained much attention as it delivers stereochemically defined di- and tri-substituted alkenes (Scheme 1A). 4 Oh's research group discovered the oxidative addition/hydropalladation sequence using a Pd(0)-boronic acid system in the presence of AcOH. 5 Later, Lautens and co-workers reported a Rh-boronic acid system that involved stereoselective hydroarylation of symmetrical alkynes via a syn addition to afford olefins as a single isomer.…”

Controllable cyclization of alkynyl thioethersviaBrønsted acid-catalyzed dearomatization

“…In the past decades, the chemical communities have witnessed substantial progress in the hydroarylation of alkynes, 1 which represents an atom-economical and benign method to construct unsaturated C-C bonds without prefunctionalization. Among the hydroarylation methods, intramolecular alkyne hydroarylation is particularly attractive as this approach provides an efficient and concise way for the construction of functionalized cyclic compounds (Scheme 1a), especially polycyclic aromatic hydrocarbons (PAHs).…”