Asymmetric exchange of cyclopalladated ligands with a high level of asymmetric induction: a new route to optically active phosphapalladacycles

Dunina, V. V.; Razmyslova, Elena D.; Gorunova, O. N.; Ливанцов, М. В.; Grishin, Yuri K.

doi:10.1016/s0957-4166(03)00496-8

Cited by 36 publications

(14 citation statements)

References 18 publications

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“…623 A new route to optically active phosphapalladocycles is afforded by the asymmetric exchange of enantiopure cyclopalladated chiral amines with prochiral phosphines. 624 The in-out isomerism of phosphorus bridgehead cage compounds has been reviewed. 625 New phosphorus cage compounds have been isolated from the reactions of tetra-t-butyltetraphosphacubane with water in the presence of gallium(I) iodide.…”

Section: Nucleophilic Attack At Other Atomsmentioning

confidence: 99%

Phosphines and Related Tervalent Phosphorus Systems

2006

Organophosphorus Chemistry

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Section: Nucleophilic Attack At Other Atomsmentioning

confidence: 99%

Phosphines and Related Tervalent Phosphorus Systems

2006

Organophosphorus Chemistry

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“…[ 2b , 11 ] There are far fewer examples of planar chiral palladacycles derived from enantioselective C–H activation. Non-racemic planar chiral palladacycles have been generated from a limited number of enantioselective transcyclopalladation reactions,[ 12 ] and in 1979 Sokolov reported the N -acetyl amino acid mediated enantioselective palladation of N , N -dimethylaminomethylferrocene ( 3 ). [ 13 ] Recent re-investigation of this latter chemistry within our group identified conditions for the synthesis of palladacycle ( S p )- 4 in 96 % ee using ( R )- N -acetylphenylalanine ( 5 ),[ 14 ] and an extension of the methodology to the kinetic resolution of [2.2]paracyclophane ( 6 ) gave palladacycle ( S p )- 7 in more than 99 % ee (Scheme 2 ).…”

Section: Introductionmentioning

confidence: 99%

Enantioselective Synthesis and Application to the Allylic Imidate Rearrangement of Amine‐Coordinated Palladacycle Catalysts of Cobalt Sandwich Complexes

Cassar

Ilyashenko

Ismail

et al. 2013

Chemistry A European J

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The reaction of (η5-(N,N-dimethylaminomethyl)cyclopentadien-yl)(η4-tetraphenylcyclobutadiene)cobalt with sodium tetrachloropalladate and (R)-N-acetylphenylalanine gave planar chiral palladacycle di-μ-chloridebis[(η5-(Sp)-2-(N,N-dimethylaminomethyl)cyclopentadienyl,1-C,3′-N)(η4-tetraphenylcyclobutadiene)cobalt]dipalladium [(Sp)-Me2-CAP-Cl] in 92 % ee and 64 % yield. Enantiopurity (>98 % ee) was achieved by purification of the monomeric (R)-proline adducts and conversion back to the chloride dimer. Treatment with AgOAc gave (Sp)-Me2-CAP-OAc which was applied to asymmetric transcyclopalladation (up to 78 % ee). The (R)-N-acetylphenylalanine mediated palladation methodology was applicable also to the corresponding N,N-diethyl (82 % ee, 39 % yield) and pyrrolidinyl (>98 % ee, 43 % yield) cobalt sandwich complexes. A combination of 5 mol % of the latter [(Sp)-Pyrr-CAP-Cl] and AgNO3 (3.8 equiv) is a catalyst for the allylic imidate rearrangement of an (E)-N-aryltrifluoroacetimidate (up to 83 % ee), and this catalyst system is also applicable to the rearrangement of a range of (E)-trichloroacetimidates (up to 99 % ee). This asymmetric efficiency combined with the simplicity of catalyst synthesis provides accessible solutions to the generation of non-racemic allylic amine derivatives.

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“…The third method based on the asymmetric activation of the C-H bond under control of an optically active base [34][35][36][37][38][39] or ligand in the palladation agent [40][41][42] is not so popular and used mainly for prochiral substrates. Except in a few cases, 41 the latter approach does not provide palladacycles in enantiomerically pure form and requires further minor enantiomer removal at the final stages.…”

Section: Introductionmentioning

confidence: 99%

“…In the course of elaboration of the new version of asymmetric cyclopalladation based on the exchange of cyclopalladated ligands 40 we have found that a high level of asymmetric induction (up to 91% ee) may be achieved only with an a-tert-Bu-substituted benzylaminate palladacycle bearing the primary amino group. Further development of this method has required large scale preparation of this efficient chirality inductor.…”

Section: Introductionmentioning

confidence: 99%