Tetrabenzylhafnium as a New Organometallic Reagent for Imine Addition Resulting in α‐Branched Amines

Mei, Haibo; Ji, Xiaoyun; Han, Jianlin; Pan, Yi

doi:10.1002/ejoc.201100820

Cited by 7 publications

(3 citation statements)

References 51 publications

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“…Deuterated benzene (C 6 D 6 ) for NMR measurements was distilled from sodium metal. Tetrabenzylzirconium, 73 tetrabenzylhafnium, 76 H 2 Me PDP Ph , 65 and H 2 Mes PDP Ph 77 were synthesized according to literature reports. All other chemicals were purchased from commercial sources and used as received.…”

Section: Methodsmentioning

confidence: 99%

“…Deuterated benzene (C 6 D 6 ) for NMR measurements was distilled from sodium metal. Tetrabenzylzirconium, 73 tetrabenzylhafnium, 76 (residual) chemical shifts of the solvent as a secondary standard. Electronic absorption spectra were recorded using a Shimadzu UV-1800 spectrophotometer in gastight quartz cuvettes with a 10 mm path length fitted with J.…”

Section: ■ Experimental Detailsmentioning

confidence: 99%

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Organometallic Intermediates in the Synthesis of Photoluminescent Zirconium and Hafnium Complexes with Pyridine Dipyrrolide Ligands

et al. 2023

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The two commercially available zirconium complexes tetrakis(dimethylamido)zirconium, Zr(NMe2)4, and tetrabenzylzirconium, ZrBn4, were investigated for their utility as starting materials in the synthesis of bis(pyridine dipyrrolide)zirconium photosensitizers, Zr(PDP)2. Reaction with one equivalent of the ligand precursor 2,6-bis(5-methyl-3-phenyl-1H-pyrrol-2-yl)pyridine, H2 MePDPPh, resulted in the isolation and structural characterization of the complexes (MePDPPh)Zr(NMe2)2thf and (MePDPPh)ZrBn2, which could be converted to the desired photosensitizer Zr(MePDPPh)2 upon addition of a second equivalent of H2 MePDPPh. Using the more sterically encumbered ligand precursor 2,6-bis(5-(2,4,6-trimethylphenyl)-3-phenyl-1H-pyrrol-2-yl)pyridine, H2 MesPDPPh, only ZrBn4 yielded the desired bis-ligand complex Zr(MesPDPPh)2. Careful monitoring of the reaction at different temperatures revealed the importance of the organometallic intermediate (cyclo-MesPDPPh)ZrBn, which was characterized by X-ray diffraction analysis and 1H NMR spectroscopy and shown to contain a cyclometalated MesPDPPh unit. Taking inspiration from the results for zirconium, syntheses for two hafnium photosensitizers, Hf(MePDPPh)2 and Hf(MesPDPPh)2, were established and shown to proceed through similar intermediates starting from tetrabenzylhafnium, HfBn4. Initial studies of the photophysical properties of the photoluminescent hafnium complexes indicate similar optical properties compared to their zirconium analogues.

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Section: Methodsmentioning

confidence: 99%

Section: ■ Experimental Detailsmentioning

confidence: 99%

Organometallic Intermediates in the Synthesis of Photoluminescent Zirconium and Hafnium Complexes with Pyridine Dipyrrolide Ligands

et al. 2023

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“…Specifically, homobenzyl amines are present in a number of HIV protease inhibitors, including Fosamprenavir and Darunavir. Previously, benzyl Grignard reagents, benzylzinc reagents,[7b], benzyltrimethylsilanes, and tetrabenzylhafnium have been employed as nucleophiles with imines. A new synthetic approach, starting from a benchtop stable organometallic reagent such as an organosilicon or organoboron that upon activation can be rendered nucleophilic is attractive.…”

Section: Introductionmentioning

confidence: 99%

Benzylation of Imines with Activated Boronate Nucleophiles

2019

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Benzylation reactions of N‐tosylimines and N‐tert‐butanesulfinyl imines using benzylboronic acid pinacol ester are reported. s‐Butyllithium was used to activate the boronic ester, rendering it nucleophilic. The reaction was compatible with electronically diverse substituents on the imine in both substrate classes. Good diastereoselectivity was observed in additions to N‐tert‐butylsulfinylaldimines. The diastereoselectivity observed in these reactions is consistent with an open transition state for the addition. Examples of a secondary alkylboronic ester nucleophile and a N‐tert‐butanesulfinyl trifluoromethylketimine electrophile are also included.

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Hafnium chloride

2017

Fieser and Fieser's Reagents for Organic Synthesis

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Tetrabenzylhafnium as a New Organometallic Reagent for Imine Addition Resulting in α‐Branched Amines

Cited by 7 publications

References 51 publications

Organometallic Intermediates in the Synthesis of Photoluminescent Zirconium and Hafnium Complexes with Pyridine Dipyrrolide Ligands

Organometallic Intermediates in the Synthesis of Photoluminescent Zirconium and Hafnium Complexes with Pyridine Dipyrrolide Ligands

Benzylation of Imines with Activated Boronate Nucleophiles

Hafnium chloride

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