(3-Ethoxy-3-oxopropyl)iodozinc

Abstract

(n = 2; R = CO2Et) [104089-16-9] C5H9IO2Zn (MW 293.43) InChI = 1S/C5H9O2.HI.Zn/c1-3-5(6)7-4-2;;/h1,3-4H2,2H3;1H;/q;;+1/p-1 InChIKey = IRYIVJVSTODHEG-UHFFFAOYSA-M (organozinc reagents functionalized with ester, ketone, nitrile, amide, or halide functionalities, capable of CC bond formation with a variety of organic electrophiles, e.g arylation, vinylation, ethynylation, acylation, allylation, Michael-type addition, and addition to carbonyl CO bonds) Alternate Name: Tamaru's reagent. Physical Data: dark powder; reagent prepared in situ (see below). Analysis of Reagent Purity: aliquots of reactions in process can be checked by VPC or TLC after addition of 1 N HCl.1c Preparative Methods: organozincs 1–5, possessing electrophilic functionality (ester, ketone, nitrile, amide, halide) in the same molecule, can be prepared in high reproducibility in mmol to mol scales by the direct reaction of the corresponding iodides and zinc metal. Four kinds of procedures have been reported. Method A:1 reaction of Zinc/Copper Couple with an iodide in benzene containing 1.5–2 equiv of DMF or DMA at 60 °C for several hours. For the preparation of zincio ketone 3, the use of HMPA in place of DMF or DMA is essential.2 For the preparation of β-zincio esters (1a–c) and β-zincio nitriles (2a–c), THF also may be used as solvent in place of benzene–DMF or DMA. Method B:3 reaction of zinc/copper couple with an iodide in benzene–DMA (2.7 equiv) under sonication at 20–35 °C for 30 min. This method is applied to the preparation of (1d), characteristically possessing an acidic amide proton. Method C:4 reaction of Zinc powder or foil, activated with 1,2‐Dibromoethane (4–5%) and Chlorotrimethylsilane (3%) in THF, with a primary iodide at 35–40 °C and with a secondary iodide at 25–30 °C in the same solvent (ca. 12 h). Method D:5 reaction of zinc metal, prepared by a slow addition of Lithium Naphthalenide (2 equiv) to a THF solution of Zinc Chloride, with an alkyl bromide at rt. The zinc powders produced by this method are very reactive and react even with vinyl bromides and aryl bromides (e.g. ethyl o- and p-bromobenzoates). Handling, Storage, and Precautions: the iodozinc reagents can be prepared and handled like Grignard reagents, and may be stored at rt for ca. one week; however, freshly prepared samples are recommended. All reactions should be conducted in a well-ventilated fume hood.