Chirale tripod-rhodium-komplexe: Ligandsynthese, komplexchemie, katalyse

Scherer, Johannes; Hüttner, Gottfried; Büchner, M; Bakos, József

doi:10.1016/0022-328x(96)06261-4

Cited by 41 publications

(13 citation statements)

References 39 publications

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“…Unreacted hydroxy groups were capped by acylation with acetic anhydride. After removal of the Boc group from 8 and 9, coupling with (R)-[binaphthyl-2,2'-diyl]chlorophosphite CIP(BINOL) (10 a) [24] yielded phosphoramidites 11 and 12 (Scheme 3). Compound 11 was obtained as mixture of isomers which could not be separated and was employed as stereodirecting ligand in the conjugate addition of ZnEt 2 to cyclohexenone 13 as such.…”

Section: Resultsmentioning

confidence: 99%

“…CH),119.9,119.8 (CHC),73.7,73.6,72.9,72.8 (CH 2 O), 52.1 (CH 2 N), 51.8 (CH 3 OCO), 51. 5,50.8,50.7 (CH 2 N),42.0,35.3,35.2 (CHC),33.51,33.49 (CH 2 COO), 26.0 (CH 2 CH), 25.36, 25.32 (CH 2 CH 2 COO); 31 P NMR (CDCl 3 , 202.5 MHz): d 148.5; IR (KBr): n Ä 2852 (Bohlmann-band), [29] 1736 cm À1 ( General procedure for the synthesis of the (3,3'-disubstituted) (R)-[binaphthyl-2,2'-diyl]-chlorophosphite 10 a ± d: [24] A solution of (3,3'-disubstituted) 2,2'-dihydroxy-[1,1']-binaphthyl [27,30] in THF was added over a period of 30 min to a solution of PCl 3 (1.3 equiv) and triethylamine (2.05 equiv) in THF. The mixture was stirred at room temperature for 90 min.…”

Section: Methodsmentioning

confidence: 99%

“…Library synthesis employing bispidine core A1 was carried out by means of two successive deprotection/N-functionalization steps (Scheme 9). Thus, after removal of the Fmoc group from 21, the nitrogen atom was derivatized by means of the 24 25…”

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Solid-Phase Development of Chiral Phosphoramidite Ligands for Enantioselective Conjugate Addition Reactions

2002

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Solid-Phase Development of Chiral Phosphoramidite Ligands for Enantioselective Conjugate Addition Reactions

2002

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“…3,3Ј,5,5Ј-Tetra(tert-butyl)-2,2Јbiphenol, [32] dimethyl-2,3-O-isoproylidene-l-tartrate, [33,34] (R,R)-TADDOL, [35] (S)-2,2Ј-dimethoxy-1,1Ј-bi-2-naphthalene, [36] (S,S)-3,3Ј-dibromo-2,2Ј-dimethoxy-1,1Ј-bi-2-naphthalene, [36,37] (S)-3,3Јdibromo-1,1Ј-binaphthol, [38] (S)-3,3Ј-bis(trimethylsilyl)-1,1Ј-binaphthol, [39] (S)-3,3Ј-biphenyl-1,1Ј-bi-2-naphthol, [40] phosphorochloridite compounds [41] and 2,2Ј-dibromo-4,4Ј-dimethyldiphenyl ether [42] were synthesized according to literature procedures. Toluene was distilled from sodium, THF and Et 2 O from sodium/benzophenone, hexane from sodium/benzophenone/triglyme, methanol and ethanol from magnesium and DCM from CaH 2 under argon atmosphere.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Reactivity of Chiral, Wide‐Bite‐Angle, Hybrid Diphosphorus Ligands

et al. 2013

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Keywords: P ligands / Synthesis design / Palladium catalysis / Rhodium catalysisEffective and modular synthetic approaches toward phosphine-phosphite ligands and phosphine-phosphonite ligands featuring a diphenyl ether backbone have been developed. The phosphine-phosphite ligands are obtained by a two-step protocol from 2-bromo-2Ј-methoxydiphenyl ether. The phosphine-phosphonite ligands are prepared in a fourstep synthetic protocol that involves a novel, unsymmetrical diphenyl ether derived phosphine-phosphorusdiamide as key building block. Structural studies on Pt II complexes with either phosphine-phosphite or phosphine-phosphonite ligands indicate strict cis coordination for these ligand systems. High-pressure NMR spectroscopy studies of Rh complexes under syngas indicate the presence of two ea isomers for Rh(H)(CO) 2 (PP). The existence of this mixture is further [a] EaSTCHEM, Scheme 1. Synthetic route to phosphine-phosphonite ligands.into the BH 3 -product 7-(BH 3 ) 2 . The 31 P NMR spectrum of 7-(BH 3 ) 2 in CD 2 Cl 2 at room temperature shows an AX spin system with broad doublets at δ = 17.8 and 88.8 ppm ( 1 J PB coupling constant of 105 Hz), assigned to the BH 3 adducts of the aminophosphine and diphenylphosphine groups, respectively.Compound 7-(BH 3 ) 2 is stable towards oxidation and hydrolysis and can be easily purified by precipitation from acetone and methanol in good yields (80 %). Crystals of 7-(BH 3 ) 2 suitable for X-ray crystallography were obtained by recrystallization by slow diffusion of hexane into a diethyl ether solution (Figure 4). The P-C bond length of the backbone to the diphenylphosphine group [1.815(4) Å] is virtually the same as the P-C bond length of the backbone to the diethylaminophosphine group [1.819(4) Å]. Both P-C bond lengths are similar to the values found for other widebite-angle ligands such as Xantphos. [16] The intramolecular distance between the two phosphorus atoms [5.803(2) Å] is larger than in Xantphos (4.080 Å), and obviously the flexible backbone has to rearrange to allow chelation of a metal atom. The P-B bonds lengths [1.910(4) and 1.918(6) Å] of both phosphorus groups are almost indistinguishable. The tetrahedral geometry is distorted around both phosphorus centres, judging from, for example, the B-P-C angles.The BH 3 protecting groups were quantitatively and smoothly removed by reaction with an equimolar amount of DABCO in toluene at 60°C overnight without affecting the P-NEt 2 bond. The 31 P NMR spectrum shows one singlet at δ = 90.9 ppm (aminophosphine) and one singlet at -18.0 ppm (phosphine). The chemical shifts of the aminophosphine and phosphine groups are in the same range as previously reported for related species. [11] Ultimately, two hybrid phosphine-phosphonite ligands were prepared by reacting (S)-BINOL derivatives with the aminophosphine moiety in refluxing toluene for one day (for 8a) or two days (8b). The longer reaction time for 8b was expected as this reaction can be hampered by steric hindrance when using too bulky diols, [19] The products we...

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“…Pyrylium salts 2a-c were obtained by Brønsted acid mediated condensation of chalcones with acetophenones. 4,5 Phosphabenzenes 3a-c 5 and (S)-(1,1¢-binaphthyl-2,2¢-dioxy)chlorophosphine (4) 7 were prepared by literature procedures. 3 J C,P = 0.9 Hz, C6), 125.2 (d, 3 J C,P = 18.5 Hz, C10¢¢¢), 125.9 (C6¢¢¢ a ), 126.0 (d, 3 J C,P = 13.0 Hz, 2 C, C2¢¢), 126.2 (C7¢¢¢ a ), 127.2 (d, 4 J C,P = 1.5 Hz, C5), 127.5 (C3¢¢¢), 127.6 (C4¢), 127.6 (d, 5 J C,P = 1.5 Hz, C4¢¢), 128.1 (d, 6 J C,P = 1.2 Hz, C5¢¢¢), 128.2 (C8¢¢¢), 128.5 (d, 4 J C,P = 0.9 Hz, 2 C, C3¢¢), 128.9 (2 C, C2¢), 129.1 (2 C, C3¢), 131.6 (d, 2 J C,P = 39.1 Hz, C3), 132.8 (d, J C,P = 1.5 Hz, C4¢¢¢ b ), 133.5 (d, Mg turnings (0.45 g, 18.52 mmol, 2.2 equiv) were suspended in a soln of phosphabenzene 3c (3.00 g, 8.47 mmol, 1.0 equiv) in THF (50 mL) and a small amount of 1-bromo-2-fluorobenzene (0.20 mL of a total of 1.93 mL, 3.09 g, 17.66 mmol, 2.1 equiv) was added to start the reaction.…”

Section: Figure 1 Chiral Phosphabarrelenesmentioning

confidence: 99%

Chiral Phosphabarrelene Ligands: Synthesis and Evaluation in Rhodium-Catalyzed Asymmetric Hydrogenation

Breit¹,

Fuchs²

2006

Synthesis

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Chirale tripod-rhodium-komplexe: Ligandsynthese, komplexchemie, katalyse

Cited by 41 publications

References 39 publications

Solid-Phase Development of Chiral Phosphoramidite Ligands for Enantioselective Conjugate Addition Reactions

Solid-Phase Development of Chiral Phosphoramidite Ligands for Enantioselective Conjugate Addition Reactions

Synthesis and Reactivity of Chiral, Wide‐Bite‐Angle, Hybrid Diphosphorus Ligands

Chiral Phosphabarrelene Ligands: Synthesis and Evaluation in Rhodium-Catalyzed Asymmetric Hydrogenation

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