PREPARATION AND REACTIVITY OF FUNCIONALIZED ALKENYL-ZINC, -COPPER, AND -CHROMIUM ORGANOMETALLICS

Article abstract of DOI:10.1016/S0040-4020(01)80504-4

β-Halogeno-α,β-unsaturated carbonyl derivatives were converted to the corresponding zinc organometallics 2a under mild conditions in THF (Zn dust, 25-45 deg C, 1-4h).These funcionalized alkenylzinc iodides react with a variety of alkenyl and aromatic iodides affording the desired coupling products in 40-97percent yield.The addition of a THF solution of CuCN*2LiCl to 2a affords the corresponding organocopper derivatives 2b which rect with electophiles, such as alkynyl and allylic halides, nitro olefins, enones, and chlorotrimethylstannane providing polyfuncional unsaturated carbonyl compounds in 71-95percent yield.The insertion of chromium (II) chloride to β-iodo and to some β-(p-tosyl)enones in DMF furnishes new funcionalized chromium (III) organometallics 2c which react with aldehydes providing γ-hydroxy unsaturated carbonyl derivatives in 40-91percent yield.The synthetic scope and the limitations of this methodology are discussed. Key words: funcionalized organozinc halides, alkenylchromium(III) compounds, copper-zinc organometallics.