Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

Abstract

SummaryCarbomagnesiation and carbozincation reactions are efficient and direct routes to prepare complex and stereodefined organomagnesium and organozinc reagents. However, carbon–carbon unsaturated bonds are generally unreactive toward organomagnesium and organozinc reagents. Thus, transition metals were employed to accomplish the carbometalation involving wide varieties of substrates and reagents. Recent advances of transition-metal-catalyzed carbomagnesiation and carbozincation reactions are reviewed in this article. The contents are separated into five sections: carbomagnesiation and carbozincation of (1) alkynes bearing an electron-withdrawing group; (2) alkynes bearing a directing group; (3) strained cyclopropenes; (4) unactivated alkynes or alkenes; and (5) substrates that have two carbon–carbon unsaturated bonds (allenes, dienes, enynes, or diynes).

Addition of arylstannanes to alkynes givingortho-alkenylarylstannanes catalysed cooperatively by a rhodium complex and zinc chloride

“…This selectivity is as expected from the reported regiochemistry at carbometalation of alkyl(aryl)alkynes. 15 …”

Asymmetric Synthesis of Alkylzincs by Rhodium‐Catalyzed Enantioselective Arylative Cyclization of 1,6‐Enynes with Arylzincs

“…[1] They have been obtained mainly from enantioenriched alkyl halides by insertion of zinc metal or halide-zinc exchange, or from other alkylmetals by transmetalation. [1,2] Catalytic enantioselective carbozincation of alkenes would be one of the promising methods of synthesizing chiral alkylzincs (Scheme 1 a), but, unfortunately, this type of asymmetric reaction has not been well developed [3] except for the addition to cyclopropene derivatives [4] and electron deficient alkenes. [5] On the other hand, Murakami [6] and we [7] independently reported rhodium-catalyzed arylative cyclization of a malonate-tethered 1,6-enyne with ArB(OH) 2 producing a bicyclo-[2.2.1]heptanone derivative.…”

“…If the ArB(OH) 2 is replaced by ArZnX and the transmetalation with ZnX 2 takes place for the alkyl-Rh intermediate, the overall reaction would be a new type of catalytic carbozincation giving alkylzinc product. During our studies on the arylzincation of carbon-carbon multiple bonds, [3,10] we found that the catalytic asymmetric carbozincation giving chiral alkylzincs shown in Scheme 1 b is realized in the presence of a chiral diene/Rh catalyst and zinc chloride.…”

Stereoselective Synthesis of Trisubstituted Alkenes through Sequential Iron‐Catalyzed Reductive anti‐Carbozincation of Terminal Alkynes and Base‐Metal‐Catalyzed Negishi Cross‐Coupling

“…Alkenylzinc reagents are generally prepared from alkenyl halides by using direct metal insertion or halogen/metal exchange 3h. 5 Alternatively, they can be prepared from alkynes by transition‐metal‐catalyzed carbozincation of alkynes by using organozinc reagents1, 6 or hydrozincation by using hydride sources 7…”