Direct C–C Bond Construction from Arylzinc Reagents and Aryl Halides without External Catalysts

Abstract

Direct cross‐coupling between an arylzinc reagent and an aryl halide was accomplished without any external catalyst, enabling efficient and selective formation of the corresponding biaryl compound with broad functional group compatibility.

Organozinc‐Mediated Direct C−C Bond Formation via C−N Bond Cleavage of Ammonium Salts

“…In both cases, the yields of the products were essentially the same as under the standard conditions, suggesting that 1) the electron transfer is initiated thermally rather than optically, and 2) the main reaction route is much faster than the generation of a free‐radical intermediate. These results are in good agreement with existing reports on the mechanisms of SET cross‐coupling reactions ––…”

“…Some elegant direct cross‐coupling reactions between organometallics (R–M) and organohalides (R–Hal) have been developed, in which R–M (such as Mg, Zn, Al, and Sn,) reacts efficiently with various types of organohalides, including R–I, R—Br, and even unreactive R–Cl (Scheme a). The mechanisms of these direct cross‐coupling reactions have been clarified by means of both experimental–– and theoretical methods. Different from the classical cross‐coupling reactions, in which electron pairs are delivered from nucleophiles to electrophiles through the TM catalyst as a bridge, most of the TM‐free couplings occur as single electron transfer (SET) processes, and can be regarded as “one‐electron‐catalyzed cross‐coupling” reactions .…”

Atom-efficient transition-metal-free arylation of N,O-acetals using diarylzinc reagents through Zn/Zn cooperativity

“…Thus, direct cross-coupling with aryl halides has been reported by Uchiyama and Wang although harsh reaction conditions are required (90–130 °C, 24 h). 3 Ingleson has also shown that coupling of benzyl and alkyl halides with ZnAr 2 can take place efficiently at room temperature using non-ethereal solvents. 4 More recently, Knochel has used ArZnX reagents to prepare triarylmethanes via sequential cross-couplings with benzal diacetates.…”

Exploiting Synergistic Effects in Organozinc Chemistry for Direct Stereoselective C‐Glycosylation Reactions at Room Temperature

“…In addition, Lemaire and co-workers have reported the direct stereoselective arylation of glycosyl bromides using arylzinc reagents, also under quite vigorous conditions (temperatures of 90-100 o C). [5] Complementary to this work, Ingleson has described the efficient room-temperature method for C(sp 2 )-C(sp 3 ) cross-coupling of a range of diarylzinc reagents with benzyl and alkyl halides. In agreement with Lemaire's work, this study also stresses that the success of the coupling heavily depends on the use of non-polar, non-coordinating solvents.…”