Organozinc

Organozinc compounds are organometallic species that contain a carbon–zinc bond. They occur in various forms, including dialkylzincs (R2Zn), alkylzinc halides (RZnX), diarylzincs (Ar2Zn), and vinyl or arylzinc derivatives. Compared with many other organometallics, organozincs are relatively less reactive, which allows for milder carbon–carbon bond-forming reactions and greater functional-group tolerance in some contexts.

Preparation and properties

Organozinc reagents are commonly prepared by oxidative insertion of zinc into carbon–halogen bonds (R–X) or by transmetalation from Grignard or organolithium reagents with zinc salts. Activated zinc, copper co-catalysts, and coordinating solvents such as THF or diethyl ether are often employed to promote formation. The resulting compounds are typically air- and moisture-sensitive, especially dialkylzinc reagents, which can be pyrophoric.

Reactions and applications

A major use of organozinc compounds is as nucleophiles in carbon–carbon bond formation. They add to aldehydes and ketones under mild conditions to furnish alcohols after workup, often with copper catalysis for improved reactivity or enantioselectivity. The most prominent application is Negishi cross-coupling, in which organozinc reagents couple with organohalides or pseudohalides under palladium or nickel catalysis to form diverse C–C bonds, demonstrating broad functional-group tolerance and utility in complex molecule synthesis.

Safety and handling

Many organozinc reagents are sensitive to air and moisture; dialkylzincs in particular are highly reactive and require rigorously inert, anhydrous conditions. Proper storage and handling under inert atmosphere are essential to prevent decomposition or hazards.