Alkylation of Electron‐Deficient Olefins through Conjugate Addition of Organozinc Reagents: An Update

Abstract

This review focuses on the applications of organozinc reagents in conjugate addition reactions. Organozinc compounds are a class of organometallic reagent used in various reactions such as addition, substitution, and coupling reactions. The conjugate addition or 1, 4-addition is one of the most useful bond forming strategies used in organic synthesis since broad range of nucleophiles can be employed in the reaction. Addition of organozinc to electron-deficient olefins attracts synthetic chemists as it preferably undergoes conjugate addition over 1,2addition unlike other organometallic reagents, such as Grignard reagent or organolithium. Many natural products were also synthesized by applying the conjugate addition reaction of organozinc. Moreover, organozinc reagents have superior functional group compatibility and can be easily prepared relative to other organometallic compounds. Consequently, conjugate additions of organozinc reagents were highly studied and having a review on it is very important at present. Though a few reviews are available, they either do not focus directly on the organozinc reagents or not on the conjugate addition. We hope that this review article will be of great use to organic researchers.

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

“…Enolate species are uniquely positioned for reactivity with a broad array of electrophiles and thus allowing quick and efficient construction of highly complex structures from readily available starting materials. Various polar organometallic reagents were successfully employed in asymmetric conjugate additions (ACA) [ 3 – 9 ], mainly organozinc [ 10 ], Grignard [ 11 – 13 ], trialkylaluminum [ 14 ], or organozirconium reagents [ 15 ]. Additions with these reagents lead to corresponding zinc, magnesium, aluminum, and zirconium enolates, which all possess helpful and, to an extent, specific reactivity characteristics.…”

Enantioselective Alkyl-Alkyl Coupling by Ni-Catalyzed Asymmetric Cross-Hydrodimerization of Alkenes

“…4 Thus, great efforts have been paid to efficiently constructing such stereogenic centers. [5][6][7][8] Among all the established methods, transition-metal-catalyzed asymmetric cross-coupling reactions between alkyl electrophiles and alkyl nucleophiles represent one of the most straightforward and efficient tool to access saturated stereogenic carbon centers by building Csp3-Csp3 bonds in an enantioselective manner. 9.10 Over the past decades, Fu and other groups have achieved significant progress in Ni-catalyzed asymmetric alkyl-alkyl cross-coupling of alkyl electrophiles with alkyl metallic reagents (Fig.…”