2-Cyanoethylzinc iodide: A new reagent with reactivity umpolung

✍ Scribed by Ming Chang P. Yeh; Paul Knochel

• Publisher: Elsevier Science
• Year: 1988
• Tongue: French
• Weight: 141 KB
• Volume: 29
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)87890-9

✦ Synopsis

Ssummarv: 2Cyanoethylzinc iodide 1 generated in over 90% yield from 3-iodopropionitrile and zinc in THP can be transmetallated to the copper and titanium derivatives 3 and 4 which react in good yields, respectively, with acyl chlorides, enones, allylic halides and benzaldehyde.

Several functionalized zinc organometallics containing a halide,l an ester-,2l3 a cyano-3 or even a ketone-314 group have been reported and used to form new carbon-carbon bonds. We have recently found that various polyfunctional alkyl iodides can be converted into the corresponding zinc derivatives in high yields3 by using zinc (activated with 4% of 1,3dibromoethane and 3% chlorouimethylsilane) in TIIP under very mild conditions (25'C for secondary iodides, 25-4O'C for primary iodides). These zinc iodides could be transmetallated into copper compounds of the new3 type RCu(CN)ZnI by using the soluble copper salt CuCN.2LiX (X = Br, Cl). We now report that our method allows the generation of 2cyanoethylzinc iodide 1 from 3-iodopropioniaile 25 and zinc in THF at 25-C in over 90% yield. Compound 1 could then be transmetallated~ with CuCN-2LiCl and Cl2Ti(Oi-Pr)2e into the copper and titanium organometallics tentatively repmsented by 3 and 4, mspectively (see Scheme 1). These new d&eagents7