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Multivalent, Sulfur‐Rich PyBox Asterisk Ligands in Asymmetric Metal Catalysis (Eur. J. Org. Chem. 31/2012)
Author(s) -
Aubert Catherine,
Dallaire Carol,
Pèpe Gérard,
Levillain E.,
Félix Guy,
Gingras Marc
Publication year - 2012
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201290084
Subject(s) - chemistry , petal , catalysis , magic bullet , hydrosilylation , rhodium , metal , sulfur , stereochemistry , medicinal chemistry , organic chemistry , botany , bioinformatics , biology
The cover picture shows white flowers of wild garlic ( Allium ursinum ), also called bear's garlic, with six petals and yellow pistils. Their bulbs are a favorite of brown bears and wild boars. In the old days, wild garlic was considered as a magic plant. It is also classified as a medicinal plant containing numerous sulfurated and odorous compounds, which is supposed to detoxify the body from heavy metals. The analogy to the PyBox asterisk ligand could not be better. Similarly, it also has six petals, contains sulfur, is able to bind heavy metals, and even has a yellow color originating from its (sulfurated) core. Additionally, the magic comes from the ability of a PyBox asterisk to modulate the enantioselectivity of a rhodium‐catalyzed hydrosilylation reaction according to its metal content. Some competitive crossover experiments with other PyBox ligands and molecular modeling calculations indicated that six proximal sulfur atoms do not inhibit this enantiocatalytic process, even at a 1 % molar ratio. The enantioselectivity mainly comes from a tight metal binding to the PyBox petals (ligands). This work promotes new thoughts about multivalent ligands in metal‐mediated catalysis. Details are discussed in the article by M. Gingras et al. on p. 6145 ff.