10.1002/chem.201902017
Chemistry - A European Journal
FULL PAPER
binding sites and partial monomerization of the Rax rotamer
occurred. Re-equilibration of ligand-additive mixtures allowed for
the rotamer distribution to be selectively shifted toward the Sax or
Rax rotamer by either inhibiting the ligand’s self-interaction or by
employing amino acid-derived additives of the same chirality as
selector sites.
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acetamidoacrylate 15 using ligand
5
gave enantiomer
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distributions of 17.4:82.6 (S:R) for the corresponding product,
which correlated to the determined rotamer distribution of the
ligand (16:84 Sax:Rax). Selectivity of the reaction could be further
altered in both directions by employing mixtures where ligand 5
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converted with very high selectivities ranging from 8.0:92.0 (S:R)
for the reduction of methyl 2-acetamidoacrylate 15 with ligand 9a
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ligand 9b. Employment of the respective phosphoramidite
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achieved with compound 10a which allowed conversion of olefin
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To the best of our knowledge, these are the first examples
where the concepts of tropos nature and supramolecular self-
interaction are combined to induce stereoconvergent behavior in
tropos ligands. Spontaneous alignment is caused by cooperative
chiral induction of chiral interaction sites, which, in turn,
translates into very high enantioselectivities in subsequent
asymmetric transformations. Consequently, presented examples
exhibit how non-covalent interactions can become a strong
driving force for the transmission of chiral information. They also
yield promising starting points for the development of
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Experimental Section
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Detailed experimental procedures can be found in the supplementary
information on the WWW under XXX.
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ganomet.9b00262.
Acknowledgements
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Generous financial support by the European Research Council
(ERC) for a Starting Grant (No. 258740, AMPCAT) and the Max-
Planck-Society is gratefully acknowledged. We thank Dr. Frank
Rominger for the X-ray structure analysis.
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Keywords: supramolecular chemistry • self-interaction •
stereodynamics • asymmetric catalysis • ligand design
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