P‐Stereogenic Pinene‐Derived Phosphoramidites and Their Use in Copper‐Catalyzed Conjugate Additions

Hobuß, Dennis; Baro, Angelika; Axenov, Kirill V.; Frey, Wolfgang

doi:10.1002/ejic.201000946

Cited by 6 publications

(3 citation statements)

References 73 publications

(14 reference statements)

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“…To a solution of N , N -diethylphosphoramidous dichloride (CAS no. 1069–08–5) (1.9 mL, 13 mmol) in THF (13 mL) was added dropwise 3,5-di( tert -butyl)-4-methoxyphenylmagnesium bromide (1.0 M in THF solution, 39 mL, 39 mmol), prepared from 1-bromo-3,5-di( tert -butyl)-4-methoxybenzene and magnesium turnings, at 0 °C, and then the mixture was warmed to room temperature. After being stirred overnight, the mixture was filtered through a pad of Celite with pentane as eluent and the filtrate was concentrated under reduced pressure.…”

Section: Methodsmentioning

confidence: 99%

“…(S)-8: the ee was measured by HPLC (Chiralpak IB column, flow 0.5 mL/min, hexane/ chloroform/ethanol = 90/30/1, 254 nm, t 1 = 11.3 min (R), t 2 = 12.0 min (S)); [α] 20 D +2 (c 1.57, CHCl 3 ) for 99% ee (S); mp 156−158 °C; 1 H NMR (CDCl 3 ) δ 1.52 (d, J = 6.9 Hz, 3H), 3.77 (s, 3H), 4.02 (q, J = 6.9 Hz, 1H), 5.35−5. 38 Procedure for Equation 3. A mixture of Co(OAc) 2 (1.8 mg, 0.010 mmol), (R,S p )-L4 (8.8 mg, 0.010 mmol), and Zn powder (1.3 mg, 0.020 mmol) in DMSO (0.3 mL) was stirred at 80 °C for 15 min under N 2 .…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Cobalt-Catalyzed Asymmetric Addition of Silylacetylenes to 1,1-Disubstituted Allenes

Sawano

Nishimura

et al. 2013

J. Org. Chem.

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The asymmetric addition of silylacetylenes to 1,1-disubstituted allenes proceeded in the presence of a cobalt/chiral bisphosphine ligand to give the corresponding enynes with high enantioselectivity. The results of deuterium-labeling experiments indicated that a hydrogen atom at the chiral center is originated from the terminal alkyne, and they were in good agreement with the proposed catalytic cycle where enantioselectivity is determined by the reaction of the proposed π-allylcobalt intermediate with the terminal alkyne.

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Section: Methodsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Cobalt-Catalyzed Asymmetric Addition of Silylacetylenes to 1,1-Disubstituted Allenes

Sawano

Nishimura

et al. 2013

J. Org. Chem.

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“…1,1-dichloro-N , N -diethylphosphanamine was prepared according to published procedure. 21 The rhodium precursor [Rh(acac)(CO) 2 ] was procured from Acros Organics and used without further purification. Syngas (1:1 mixture of CO:H 2 ) was supplied by Ms. Vadilal Chemicals Ltd., Pune, India.…”

Section: Generalmentioning

confidence: 99%

Synthesis of meta-substituted monodentate phosphinite ligands and implication in hydroformylation $$^\dagger $$ †

et al. 2017

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Synthesis of meta-substituted phosphinite ligands 3,3-(methoxyphosphanediyl)bis(N ,Ndiethylaniline) (4a) and methoxybis(3-methoxyphenyl)phosphane (4b), in high yields, has been demonstrated. Typical phosphorus chemical shift between 110-120 ppm, appearance of methoxy protons and corresponding carbon, as well as ESI-MS spectra unambiguously confirmed the existence of phosphinite ligands 4a and 4b. To demonstrate the synthetic usefulness of 4a and 4b, these ligands were tested in the rhodium catalyzed hydroformylation of 1-octene. The diethylamine substituted ligand 4a was found to be highly active, whereas 4b was less reactive but revealed slightly better regioselectivity of 62% under optimized conditions. Additionally, 4a and 4b were found to catalyze the hydroformylation of styrene, 1-undecenol and 1,1-disubstituted functional olefin, methyl methacrylate. Both the ligands displayed excellent conversion of styrene, and 4b revealed an excellent branch selectivity of 75%. Although 1-undecenol proved to be amenable to hydroformylation (85-90% conversion to aldehyde), both the ligands failed to discriminate between the linear and branched products. Substrate methyl methacrylate proved to be highly challenging and reduced conversion (between 33-42%) was observed under optimized conditions. Ligand 4a was found to be highly selective towards linear aldehyde (81% linear selectivity).

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Modulation of Multifunctional N,O,P Ligands for Enantioselective Copper‐Catalyzed Conjugate Addition of Diethylzinc and Trapping of the Zinc Enolate

Ye¹,

Zheng²,

Deng³

et al. 2013

Chemistry An Asian Journal

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In this work, we have successfully synthesized a new family of chiral Schiff base–phosphine ligands derived from chiral binaphthol (BINOL) and chiral primary amine. The controllable synthesis of a novel hexadentate and tetradentate N,O,P ligand that contains both axial and sp3-central chirality from axial BINOL and sp3-central primary amine led to the establishment of an efficient multifunctional N,O,P ligand for copper-catalyzed conjugate addition of an organozinc reagent. In the asymmetric conjugate reaction of organozinc reagents to enones, the polymer-like bimetallic multinuclear Cu-Zn complex constructed in situ was found to be substrate-selective and a highly excellent catalyst for diethylzinc reagents in terms of enantioselectivity (up to >99 % ee). More importantly, the chirality matching between different chiral sources, C2-axial binaphthol and sp3-central chiral phosphine, was crucial to the enantioselective induction in this reaction. The experimental results indicated that our chiral ligand (R,S,S)-L1- and (R,S)-L4-based bimetallic complex catalyst system exhibited the highest catalytic performance to date in terms of enantioselectivity and conversion even in the presence of 0.005 mol % of catalyst (S/C = 20 000, turnover number (TON) = 17,600). We also studied the tandem silylation or acylation of enantiomerically enriched zinc enolates that formed in situ from copper-L4-complex-catalyzed conjugate addition, which resulted in the high-yield synthesis of chiral silyl enol ethers and enoacetates, respectively. Furthermore, the specialized structure of the present multifunctional N,O,P ligand L1 or L4, and the corresponding mechanistic study of the copper catalyst system were investigated by 31P NMR spectroscopy, circular dichroism (CD), and UV/Vis absorption.

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P‐Stereogenic Pinene‐Derived Phosphoramidites and Their Use in Copper‐Catalyzed Conjugate Additions

Cited by 6 publications

References 73 publications

Cobalt-Catalyzed Asymmetric Addition of Silylacetylenes to 1,1-Disubstituted Allenes

Cobalt-Catalyzed Asymmetric Addition of Silylacetylenes to 1,1-Disubstituted Allenes

Synthesis of meta-substituted monodentate phosphinite ligands and implication in hydroformylation $$^\dagger $$ †

Modulation of Multifunctional N,O,P Ligands for Enantioselective Copper‐Catalyzed Conjugate Addition of Diethylzinc and Trapping of the Zinc Enolate

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