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Catalytic Asymmetric Chlorination of β ‐Keto Esters with Hypervalent Iodine Compounds
Author(s) -
Ibrahim Hasim,
Kleinbeck Florian,
Togni Antonio
Publication year - 2004
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200490058
Subject(s) - chemistry , hypervalent molecule , acetonitrile , catalysis , iodine , toluene , selectivity , medicinal chemistry , titanium , organic chemistry
(Dichloroiodo)toluene (=dichloro(4‐methylphenyl)iodine; 2 ) was found to be a suitable chlorinating agent in the catalytic asymmetric chlorination of β ‐keto esters 3 catalyzed by the [Ti(TADDOLato)] complex 1 (=bis(acetonitrile)dichloro[(4 R ,5 R )‐2,2‐dimethyl‐ α , α , α ′, α ′‐tetra(naphthalen‐1‐yl)‐1,3‐dioxolane‐4,5‐dimethanolato(2−)‐ κO , κO ′]titanium), whereby α ‐chlorinated products were obtained in moderate to good yields and enantioselectivities of up to 71% ( Scheme 2, Table 2 ). The enantioselectivity of the reaction shows a remarkable temperature dependence, the maximum selectivity being obtained at ca. 50°.