Improved Air-Stable Solid Aromatic and Heterocyclic Zinc Reagents by Highly Selective Metalations for Negishi Cross-Couplings
作者:Christos I. Stathakis、Sebastian Bernhardt、Valentin Quint、Paul Knochel
DOI:10.1002/anie.201204526
日期:2012.9.10
Directed metalation using TMPMgCl⋅LiCl (TMP=2,2,6,6‐tetramethylpiperidide) and subsequent transmetalation with Zn(OPiv)2 leads to aryl and heteroaryl zinc pivalates. After solvent evaporation, easy‐to‐handle fine powders are obtained that retain most of their activity (>85 %) when exposed to air for 4 h. They smoothly undergo Negishi cross‐couplings, and technical‐grade solvents can be used without
The present invention relates to compositions containing a zinc complex wherein a zinc atom carries two amide ligands, a lithium salt and a defined solvent. The compositions are stable and show high activity as reactants for metalation reactions, and thus provide a valuable tool in organic synthesis. Moreover, the invention relates to processes for the preparation of the compositions and to synthetic procedures using them.
Regioselective Functionalization of Purine Derivatives at Positions 8 and 6 Using Hindered TMP-Amide Bases of Zn and Mg
作者:Paul Knochel、François Crestey、Silvia Zimdars
DOI:10.1055/s-0033-1338524
日期:——
A broad range of purine derivatives were efficiently metalated at positions 8 and 6 using TMP-amide bases. This provided polysubstituted purines in good to very good yields after subsequent trapping of the zinc or magnesium intermediates with various electrophiles.