Synthesis of hemilabile P,N-ligands with a pentane-2,4-diyl backbone

Farkas, Gergely; Császár, Zsófia; Balogh, Szabolcs; Tóth, Imre; Bakos, József

doi:10.1016/j.tetlet.2014.05.091

Cited by 11 publications

(5 citation statements)

References 36 publications

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“…The synthesis of the novel diastereomerically related ligand sets 4 and 5 was accomplished in moderate yields starting from the same source of chirality, cyclic sulfate of ( R , R )‐pentane‐2,4‐diol (Scheme ). In the first step, the nucleophilic ring opening of the cyclic sulfate with the corresponding amine resulted in the formation of zwitterionic compounds 1 . The ring closing reaction of 1a–c produces optically pure azetidines 2a–c in high yields (60–91%).…”

Section: Resultsmentioning

confidence: 99%

“…Solvents were purified, dried and deoxygenated by standard methods. Compounds [Pd (COD)Cl 2 ], [Pd(η 3 ‐PhCHCHCHPh)(COD)]BF 4 ,[5i] 3a , b and 3c were prepared according to literature methods. All other starting materials were purchased from Sigma Aldrich and used without further purification.…”

Section: Methodsmentioning

confidence: 99%

“…In the first step, the nucleophilic ring opening of the cyclic sulfate with the corresponding amine resulted in the formation of zwitterionic compounds 1. [16] The ring closing reaction of 1a-c produces optically pure azetidines 2a-c in high yields (60-91%). It should be noted that optically pure azetidines are valuable starting compounds in synthetic organic chemistry.…”

Section: Synthesis Of the Ligandsmentioning

confidence: 99%

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Double stereoselective coordination of chiral N,S ligands: Synthesis, coordination chemistry and utilization in Pd‐catalyzed allylic alkylation

Major

Rövid

Balogh

et al. 2018

Applied Organom Chemis

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A series of chiral pentane‐2,4‐diyl‐based thioether‐amine ligands [4 and 5; (R,S)‐ and (S,S)‐R1SCH(CH3)CH2CH(CH3)NHR2, respectively, where 4a R1 = iPr, R2 = Ph; 4b R1 = tBu, R2 = Ph; 4c R1 = 1‐Ad, R2 = Ph; 5a R1 = iPr, R2 = Ph; 5b R1 = tBu, R2 = Ph; 5c R1 = 1‐Ad, R2 = Ph; 5d R1 = iPr, R2 = 4‐MeOC6H4; 5e R1 = iPr, R2 = 4‐MeC6H4; 5f R1 = iPr, R2 = 3,5‐Me2C6H3] with stereogenic S‐ and N‐donor atoms has been prepared starting from cyclic sulfates via optically pure γ‐aminoalcohol or 2,4‐dimethylazetidine intermediates. The synthesis of the novel diastereomerically related ligand sets 4 and 5 was accomplished starting from the same source of chirality. The modular ligand structure and the novel synthetic strategies developed for their synthesis allowed the easy modification of the ligands’ (i) S‐ and (ii) N‐substituents, as well as (iii) the relative stereochemistry within the ligand backbone. Six‐membered [Pd(N,S)Cl2]‐type chelate complexes of the diastereomerically related ligands 4a and 5a were synthesized and characterized by X‐ray crystallography in the solid phase, by density functional theory calculations and in solution by NMR spectroscopy. The coordination of 5a resulted in the formation of a single chair conformation by the stereospecific locking of both stereolabile (N and S) donor atoms. In contrast, compound 4a forms rapidly equilibrating palladium species due to the fast inversion of the sulfur donor. Ligands with stereochemically fixed donor atoms provided robust and efficient catalytic systems that can be effectively applied in alkylene carbonates as green reaction media. Remarkably, the phosphine‐free catalysts are air‐stable, and at room temperature in the presence of moisture gave excellent ee’s (up to 93%) in asymmetric allylation processes thanks to the double stereoselective coordination.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Synthesis Of the Ligandsmentioning

confidence: 99%

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Double stereoselective coordination of chiral N,S ligands: Synthesis, coordination chemistry and utilization in Pd‐catalyzed allylic alkylation

Major

Rövid

Balogh

et al. 2018

Applied Organom Chemis

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“…In order to shed light on the possible CH 2 linkage effects in the unusual complex formation reaction, we extended our studies to P,N ligands of different tether length. Chiral ligands 1a−f (Scheme 1) were synthesized in an optically pure form according to literature methods (1b−d) 10 or to its slightly modified variant (1a,e,f).…”

mentioning

confidence: 99%

“…Chiral ligands 1a – f (Scheme ) were synthesized in an optically pure form according to literature methods ( 1b – d ) or to its slightly modified variant ( 1a , e , f ).…”

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confidence: 99%

Synthesis of zwitterionic phosphapalladacycles: unusual reactivity pattern of six-membered P,N-chelates

et al. 2018

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A cyclometalation motif has been discovered in the unprecedented reaction of Pd(II) precursors with simple pentane-2,4-diyl based aminoalkyl-phosphines. The unique six-membered zwitterionic palladacycles can easily be synthesized in the presence of 1 molar equiv of oxidant in high yields in a pure form. A comparison between the analogous ligands of different tether lengths revealed that the formation of the zwitterionic palladacycles is the exclusive privilege of the six-membered rings.

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ChemInform Abstract: Synthesis of Hemilabile P,N‐Ligands with a Pentane‐2,4‐diyl Backbone.

et al. 2014

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Synthesis of hemilabile P,N-ligands with a pentane-2,4-diyl backbone

Cited by 11 publications

References 36 publications

Double stereoselective coordination of chiral N,S ligands: Synthesis, coordination chemistry and utilization in Pd‐catalyzed allylic alkylation

Double stereoselective coordination of chiral N,S ligands: Synthesis, coordination chemistry and utilization in Pd‐catalyzed allylic alkylation

Synthesis of zwitterionic phosphapalladacycles: unusual reactivity pattern of six-membered P,N-chelates

ChemInform Abstract: Synthesis of Hemilabile P,N‐Ligands with a Pentane‐2,4‐diyl Backbone.

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