Advances in tandem reactions with organozinc reagents

Abstract

The design and implementation of tandem reactions provides organic chemists with numerous challenges, in particular that of undesired cross-reactivity between substrates. Among organometallics, the use of organozinc reagents in tandem reactions provides several advantages as a result of their broad functional group tolerance and compatibility with transition metals. This review highlights prominent examples of recent advances in tandem reactions with organozinc reagents that illustrate their potential in organic synthesis.

Guanine‐La complex supported onto SBA‐15: A novel efficient heterogeneous mesoporous nanocatalyst for one‐pot, multi‐component Tandem Knoevenagel condensation–Michael addition–cyclization Reactions

“…Thus, they can combine high levels of complex and diverse generations with low synthetic cost and high atom‐economy and also reduce the waste generation and synthetic efficiency . Consequently, tandem reactions not only reduce the number of reaction steps, energy consumption and waste but also minimize the use of solvents and reagents . These advantages make tandem reactions sustainably green processes that illustrate the concepts of efficiency and atom economy .…”

“…Consequently, tandem reactions not only reduce the number of reaction steps, energy consumption and waste but also minimize the use of solvents and reagents . These advantages make tandem reactions sustainably green processes that illustrate the concepts of efficiency and atom economy . Tandem reactions offer many opportunities to improve chemical transformations such as Lewis acid–base catalysis, hydrogenation reactions and alkene metathesis .…”

An Efficient Approach to Regio‐ and Stereodefined Fully‐Substituted Alkenylsilanes by Pd‐Catalyzed Allenic C(sp3)−H Oxidation

“…Functionalized tetrasubstituted olefins, in which one of the substituents is a functional group, are considered as a class of useful and fundamental building blocks for complex molecules in organic synthesis (Scheme a) . In this field, alkenyl halides have shown wide applications as electrophiles in coupling reactions, whereas alkenylmetal reagents, such as alkenylmagnesium and alkenylzinc reagents are used as nucleophiles in carbon–carbon bond forming reactions . However, the use of these strong nucleophiles is usually associated with problems concerning functional group compatibility.…”

“…[6] In this field, alkenyl halidesh aves hown wide applicationsa se lectrophiles in coupling reactions, [7] whereas alkenylmetal reagents, such as alkenylmagnesium and alkenylzinc reagents are used as nucleophilesi nc arbon-carbonb ond forming reactions. [8] However,t he use of these strong nucleophiles is usually associated with problemsc oncerning functional group compatibility. For example, carbonyl compounds, including aldehydes and ketones,a re sensitive to alkenylmetal reagents of magnesium and zinc.…”

Umpolung Addition of Aldehydes to Aryl Imines

“…[1,2] Over the past decades,tremendous efforts have been devoted to the synthesis of aw ide array of amines.I n particular,t he direct nucleophilic addition of organometallic reagents (e.g., Grignard reagents) to imines represents ap owerful synthetic method for such purposes. [3] Despite the robustness of reactivity,most organometallic reagents are typically prepared from stoichiometric amounts of the corresponding metals and organic halides (Scheme 1a). Another obvious drawback associated with this high reactivity is the poor chemoselectivity,e xemplified by low functional group compatibility towards,a mong others,e sters, amides,and nitriles.Alternative strategies for amine synthesis include the Mannich reaction via enolate formation [4] (Scheme 1b)a sw ell as the umpolung addition of aldehydes to imines,f or example in benzoin-type condensations (Scheme 1c) [5,6] and pinacol-type couplings (Scheme 1d).…”