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Stabilization of a Chiral Dirhodium Carbene by Encapsulation and a Discussion of the Stereochemical Implications
Author(s) -
Werlé Christophe,
Goddard Richard,
Philipps Petra,
Farès Christophe,
Fürstner Alois
Publication year - 2016
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201605502
Subject(s) - chemistry , phthalimide , carbene , cyclopropanation , stereochemistry , asymmetric carbon , organic chemistry , catalysis , optically active
For the first time, the stereochemical course of an asymmetric cyclopropanation can be discussed on the basis of experimental structural information on a pertinent chiral dirhodium carbene intermediate. Key to success was the formation of racemic single crystals of a heterochiral [Rh 2 {(S*)‐PTTL} 4 {=C(Ar)COOMe}][Rh 2 {(R*)‐PTTL} 4 ] (Ar=MeOC 6 H 4 ; PTTL= N ‐phthaloyl‐ tert ‐leucinate) capsule, which has been characterized by X‐ray diffraction. NMR spectroscopic data confirm that the obtained structural portrait is also relevant in solution and provide additional information about the dynamics of this species. The chiral binding pocket is primarily defined by the conformational preferences of the N ‐phthaloyl‐protected amino acid ligands and reinforced by a network of weak interligand interactions that get stronger when chlorinated phthalimide residues are used.