Carbozincation of Alkenes and Alkynes

Abstract

Introduction Reactivity of Alkyl and Aryl Organozinc Reagents Reactivity of Allylic Organozinc Reagents Reactivity of Allenylzinc Reagents Reactivity of Zinc Enolates and Aza‐Enolates Conclusion

Regioselective 1,4-Conjugate Addition of Grignard Reagents to α,β–γ,δ-Dienones and α,β–γ,δ-Dienyl Thiol Esters

“…The 1,4-addition of carbon nucleophiles to alkenes conjugated to electron-withdrawing groups was first reported by Claisen–Komnenos (1883) and shortly thereafter developed by Michael into a potent synthetic method . Evolving from β-dicarboxyl enolates (Michael reaction, 1887), synthetic utility of the conjugate addition of carbanions to Michael acceptors followed the trend of carbanion stability with the chronological application of ketone enolates (Robinson annulation, 1935), cuprates (1941, 1966), zincates (1977), , and in limited cases Grignard , and organolithium reagents. Kharasch and Reinmuth reported, in a 1954 monograph, over 60 examples of Grignard reagents reacting with simple acyclic α,β-unsaturated ketones to give variable mixtures of 1,2- and 1,4-addition products.…”

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

“…Hence, limited substrates and reagents could be employed for uncatalyzed intermolecular carbometalation. Naturally, many groups envisioned transition-metal-catalyzed carbometalation reactions that directly convert alkynes and alkenes to new organomagnesium and organozinc reagents [14–33]. The resulting organomagnesium and organozinc intermediates have versatile reactivity toward various electrophiles to provide multisubstituted alkenes and alkanes.…”

γ-Selective Allylation of (E)-Alkenylzinc Iodides Prepared by Reductive Coupling of Arylacetylenes with Alkyl Iodides

“…Both approaches are limited by the difficulty to obtain stereochemically pure alkenyl halides . Alkenylzinc reagents can also be prepared by carbozincation of alkynes with organozinc reagents . This approach is potentially stereoselective, but it requires reactive organometallic reagents which can be hard to handle or can lower functional group compatibility.…”

“…15 Alkenylzinc reagents can also be prepared by carbozincation of alkynes with organozinc reagents. 16 This approach is potentially stereoselective, but it requires reactive organometallic reagents which can be hard to handle or can lower functional group compatibility. We have recently reported Fe-catalyzed reductive coupling of arylacetylenes with alkyl halides to form cis-alkenes.…”