A multivalent PyBox asterisk ligand

Aubert, C.; Dallaire, Carol; Gingras, Marc

doi:10.1016/j.tetlet.2008.06.075

Cited by 4 publications

(3 citation statements)

References 36 publications

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“…Among many applications, the arena of PyBox‐mediated reactions includes aldol condensation,7 cyclopropanation,8 Diels–Alder cycloaddition,9 hydrosilylation of ketones,10 alkene epoxidation,11 1,3‐dipolar cycloaddition,12 ene reactions,13 Negishi couplings,14 cyanation,15 and Friedel–Crafts reactions 16. In our multivalency studies, we designed PyBox asterisk ligand 1 (Figure 1), as well as monovalent model PyBox 2 , as a reference 17. The high density of the proximal Pybox units, an easy persulfuration of a benzene core, and a dendritic simplification guided us in the structural choice of 1 .…”

Section: Introductionmentioning

confidence: 99%

“…Our longstanding efforts in the development of persulfurated aromatic compounds18 have led us to various applications and topics, including molecular asterisks,19 dendrimers,20 supramolecular chemistry,21 self‐assembly on metal surfaces,22 ionophores for making ion‐selective membranes,23 and multivalent ligands for probing lectin–carbohydrate interactions 24. Since the first reports of their identification in 1957, persulfurated aromatic compounds have only rarely been tested as ligands in transition‐metal‐catalyzed reactions 17,18. We investigated such an opportunity here by making Pybox asterisk 1 .…”

Section: Introductionmentioning

confidence: 99%

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Multivalent, Sulfur‐Rich PyBox Asterisk Ligands in Asymmetric Metal Catalysis

Aubert¹,

Dallaire²,

Pèpe³

et al. 2012

Eur J Org Chem

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Multivalent PyBox asterisk ligand 1 and monovalent ligand 2 are reported. The innovative feature in 1 is a sulfur‐rich persulfurated benzene core as a template joining six PyBox units in close proximity. An efficient persulfuration of C6Cl6 with p‐methoxybenzenethiol (95 %, >99 % per C–S bond) and deprotection led to hexaphenol 4. Six O‐arylations of 4 with Cl‐PyBox 3 (94 %, >99 % per C–O bond) provided 1. The electronic delocalization of 1 and 2 was analyzed by UV/Vis spectroscopy and cyclic voltammetry. PyBox ligands 1 and 2 were successfully used for Rh‐catalyzed hydrosilylation of acetophenone, in spite of competitive bindings from six proximal sulfur atoms. The concept of multivalency and the presence of donating and oxidizable sulfur atoms in asymmetric metal catalysis were tested. The reactivities and the enantiocatalytic behavior of 1 and 2 with varying rhodium content were determined. Lability of the Rh complexes under certain conditions, was demonstrated by some crossover experiments with other PyBox ligands. Conformational and competitive metal binding studies of 1 with the aid of molecular modeling (GenMol™) helped to explain the results. This work suggests new directions for simple multivalent ligands in metal‐mediated catalysis.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multivalent, Sulfur‐Rich PyBox Asterisk Ligands in Asymmetric Metal Catalysis

Aubert¹,

Dallaire²,

Pèpe³

et al. 2012

Eur J Org Chem

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“…9 Ligands possessing persulfurated benzene cores for metal sensing devices have been developed. 10 In polymer chemistry, they have found interest as stabilizers 1 or, very recently, as high-refractive-index and transparent polymers. 11 Some compounds have been developed as efficient catalysts in the synthesis of gold nanoparticles.…”

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confidence: 99%

Sulfanyl-Substituted [3]Cumulenes and Buta-1,3-dienes from a Tetrakis(pyridinium)-Substituted Butadiene

Schmidt¹,

Rahimi²,

Gjikaj³

2009

Synthesis

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Treatment of perchlorobuta-1,3-diene with 4-(N,N-dimethylamino)pyridine resulted in the formation of 1,1¢,1¢¢,1¢¢¢-(2,3-dichlorobuta-1,3-diene-1,1,4,4-tetrayl)tetrakis[4-(dimethylamino)pyridinium] tetrachloride (structure confirmed by X-ray analysis), which was converted into persulfurated butatrienes ([3]cumulenes), pentakis(sulfanyl)-substituted buta-1,3-dienes, or tetrakis(sulfanyl)-substituted 2,3-dichlorobuta-1,3-dienes by reactions with thiolates or a sulfinate. The outcome of the reaction depends on the reaction conditions and the substitution pattern of the starting sulfur nucleophiles.

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