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On the Scope of Trimethylaluminium‐Promoted 1,2‐Additions of ArZnX Reagents to Aldehydes
Author(s) -
Glynn Daniel,
Shan Jonathan,
Woodward Simon
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200901803
Subject(s) - reagent , electrophile , chemistry , aryl , catalysis , halide , combinatorial chemistry , transition metal , palladium , organic chemistry , alkyl
A practical asymmetric 1,2‐addition of functionalised arylzinc halides to aromatic and aliphatic aldehydes is described by the use of aminoalcohol catalysis in the presence of AlMe 3 . The process is simple to carry out, uses only commercially available reagents/ligands and provides moderate to good (80–96 % ee ) enantioselectivities for a wide range of substrates. Either commercial ArZnX reagents or those prepared in situ from low cost aryl bromides can be used. In the latter case electrophilic functional groups are tolerated (CO 2 Et, CN). The reaction relies on rapid exchange between ArZnX and AlMe 3 to generate mixed organometallic species that lead to the formation of a key intermediate that is distinctly different from the classic “ anti ” transition states of Noyori. NMR monitoring and related experiments have been used to probe the validity of the proposed selective transition state.