Organic synthesis reagent (27)-Zinc benzeneselenide halide
Structural formula:
English name: Phenylselenyl zinc chloride
Molecular formula: C6H5ClSeZn
Molecular weight: 140.57
CAS No.: Not available (CAS No. 5707-04-0 in the original article was searched to indicate phenylselenyl chloride)
Whether commercialized reagent: No
Physical Properties: white solid, bp 107~108 °C / 1.0 mmHg. soluble in toluene.
Preparation: Can be obtained by oxidative addition of commercially available phenylselenium chloride to zinc powder in THF.
Caution for use: This reagent is strongly hygroscopic. It is toxic and harmful to the environment and should be handled in a fume hood. Store at low temperatures.
Zinc chloride (or bromide) benzeneselenide is a stable selenium-containing compound [1]. It is mainly used as a nucleophilic reagent to synthesize organic compounds containing selenium. Mostly water and THF are used as solvents, and it can react with compounds containing easily dissociated groups by SN2 reaction to obtain the corresponding substitution products . The ability of leaving group can be referred to: Organic synthesis of common leaving group ordering summary
In THF or aqueous solution, vinyl halides can undergo nucleophilic substitution reactions with zinc benzeneselenide halides to give the corresponding E-configuration substitution products. The configuration of the reactants remains unchanged during the substitution reaction, and the reaction is more effective in aqueous media. However, when β-halo-α,β-unsaturated ketones are used to react with zinc benzeneselenide halides, the Z-configuration is obtained due to the combination of the carbonyl group with zinc.
Organozinc reagents are widely used in the construction of carbon-carbon and carbon-heteroatom bonds due to their good functional group tolerance and stability and low toxicity. Although powerful reactions have allowed asymmetric synthesis using racemic reagents in recent years, transition metal catalysis has further broadened the application of non-racemic organozinc reagents. The most common method of preparing organozinc reagents is the insertion of zinc into an
organohalide, but this process typically passes through a radical intermediate, which makes asymmetric synthesis challenging. Other methods of preparing chiral organozinc reagents have been developed.Knochel’s team developed a borohydride and subsequent boron-zinc exchange strategy to obtain chiral organozinc reagents (Fig. 1a); Campos obtained heterocyclic organozinc reagents by deprotonation/transmetalation (Fig. 1b), a strategy that was later modified by Gawley to use catalytic quantities of lithiated diaminol salts (Fig. 1c); more recently, Knochel’s team obtained chiral dialkyl zinc reagents by lithium-halogen atom exchange and subsequent transmetalation (Fig. 1d). direct carbon-zincation of π-bonds is one of the very special methods, but has been reported very rarely and is only possible for alkenes with stress and activation (Fig. 1e). In this paper, James P. Morken of Boston College developed the carbon-zincation of vinylboronic esters with the
participation of chiral nickel catalysts to obtain chiral α-boron zinc reagents, which are conformationally stable products that can be reacted with a wide range of electrophilic reagents to obtain chiral alkyl boronic esters
