[EN] ORGANOZINC COMPLEXES AND PROCESSES FOR MAKING AND USING THE SAME [FR] COMPLEXES D'ORGANOZINC ET PROCÉDÉS POUR LEUR FABRICATION ET LEUR UTILISATION
Cobalt in Organic Synthesis Abstract A robust and scalable CoCl2-catalyzed cross-coupling between functionalized arylzinc pivalates and various electron-poor (hetero)aryl and alkenyl halides is reported. A robust and scalable CoCl2-catalyzed cross-coupling between functionalized arylzinc pivalates and various electron-poor (hetero)aryl and alkenyl halides is reported.
Air-Stable Solid Aryl and Heteroaryl Organozinc Pivalates: Syntheses and Applications in Organic Synthesis
作者:Sophia M. Manolikakes、Mario Ellwart、Christos I. Stathakis、Paul Knochel
DOI:10.1002/chem.201403015
日期:2014.9.15
air‐stable, solid, polyfunctionalaryl and heteroarylzinc pivalates were efficiently prepared by either magnesiuminsertion or Hal/Mg exchange followed by transmetalation with Zn(OPiv)2 (OPiv=pivalate). By reducing the amount of LiCl the air stability could be significantly enhanced compared with previously prepared reagents. An alternative route is directed magnesiation using TMPMgCl⋅LiCl (TMP=2,2,6,6‐
Organozinc pivalates, a recently developed air‐ and moisture‐stable organozinc species, were found for the first time as excellent organometallic species in the monoorganylation of trialkyl borates whereby boronic acids were prepared in high yields. The significant advantage of organozinc pivalates over another previously employed organometallic reagents, e. g., organolithium reagents, Grignard reagents
Cobalt-catalyzed acylation-reactions of (hetero)arylzinc pivalates with thiopyridyl ester derivatives
作者:Ferdinand H. Lutter、Lucie Grokenberger、Maximilian S. Hofmayer、Paul Knochel
DOI:10.1039/c9sc01817d
日期:——
A cobalt-catalyzed acylation reaction of various primary, secondary and tertiary alkyl, benzyl and (hetero)aryl S-pyridyl thioesters with (hetero)arylzinc pivalates is reported. The thioesters were prepared directly from the corresponding carboxylic acids under mild conditions, thus tolerating sensitive functional groups. Acylations of α-chiral S-pyridyl esters proceeded with very high stereoretention
Powdered organozinc reagents: Various aryl and heteroaryl bromides as well as benzylic chlorides react with Mg and Zn(OPiv)2⋅2 LiCl (OPiv=pivalate) to provide solid organozinc reagents after solvent evaporation. These powders can be stored at room temperature under argon for months and can be manipulated in air for a short time. They undergo smooth Negishi cross‐coupling and carbonyl addition reactions