N,N′-Bis(9H-fluoren-9-ylidene)benzene-1,2-diamine

Glagovich, Neil M.; Reed, Elizabeth M.; Crundwell, Guy; Updegraff, James B.; Zeller, Mat­thias; Hunter, Allen D.

doi:10.1107/s1600536805010251

Cited by 4 publications

(2 citation statements)

References 7 publications

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“…Taylor and Fletcher reported the facile synthesis of thirty-two fluorene-based Schiffbases in 1956 [16]. However, few papers were reported concerning further studies of these compounds in recent years [17][18][19]. Recently, a facile synthesis of several novel fluorene-based bis-Schiff bases has been developed [20].…”

Section: Introductionmentioning

confidence: 97%

Crystal structure and DFT studies of N1,N6-Di(9H-fluoren-9-ylidene)hexane-1,6-diamine

Yuan

2013

Journal of Molecular Structure

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Section: Introductionmentioning

confidence: 97%

Crystal structure and DFT studies of N1,N6-Di(9H-fluoren-9-ylidene)hexane-1,6-diamine

Yuan

2013

Journal of Molecular Structure

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“…Imines themselves (both as chiral or achiral substrates) are employed as precursors of active species in organocatalytic reactions like hydroxylation, epoxidation, and aziridination . A conformationally chiral diimine was recently observed in the solid state in its racemic form . In solution, however, imines are known to undergo stereodynamic processes that involve the trigonal nitrogen atom coplanar to the atoms to which it is bonded.…”

Section: Introductionmentioning

confidence: 99%

Structure and Stereodynamics of Aryldiimino Derivatives

2010

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Aromatic diimino derivatives, having two N=CPh(2) moieties bonded at the 1,8 positions of the anthraquinone, anthracene, biphenylene, and naphthalene rings, have been investigated by variable-temperature NMR spectroscopy, X-ray diffraction, and DFT calculations. In all the compounds, the imino substituents are essentially orthogonal to the aromatic plane and the phenyl groups bonded to the C=N carbons are diastereotopic (i.e., cis or trans to the aromatic N-substituent of the N=C moiety). The barriers for the cis/trans interconversion of the phenyl groups by planar nitrogen inversion have been determined. In the cases of anthracene and anthraquinone derivatives, the presence of syn and anti conformers was detected, and their interconversion barriers, due to the Ar-N rotation, were measured. At very low temperature, restricted rotations of the phenyl groups, displaying barriers in the range 4.8-6.9 kcal mol(-1), were also observed for all compounds: the barriers for the rotation of the cis were found to be larger than for the trans phenyl groups.

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N‐Heterocyclic Carbenes Functioning as Monoligating Clamps

et al. 2013

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International audienceBenzimidazolium salts N,N′-disubstituted with 9-alkylfluorenyl groups (3a-e, alkyl = methyl, ethyl, propyl, butyl, benzyl) have been synthesised in high yields in three steps from o-phenylenediamine. This amine was treated with fluorenone in the presence of TiCl4 and tetramethylethylenediamine (TMEDA) to form N,N′-bis(9H-fluoren-9-ylidene)benzene-1,2-diamine (1) in 91 % yield. Diamines 2a-e were then obtained in yields superior or equal to 77 % by reacting diimine 1 with the appropriate organolithium reagent. In the final step, diamines 2a-e were treated with ethylorthoformate under acidic conditions to afford benzimidazolium salts 3a-e. These were readily converted into the PEPPSI palladium complexes 4a-e (PEPPSI = pyridine-enhanced precatalyst preparation stabilisation and initiation). NMR and X-ray diffraction studies revealed that the flat fluorenylidene moiety orientates the alkyl groups towards the metal centre and because of its restricted rotational freedom makes the ligand bulkiness time independent. Thus, the metal centre is permanently confined between the two alkyl groups, and thereby forms a monoligating clamp with the carbenic centre. The CH2 groups close to the palladium ion give rise to anagostic C-H***Pd interactions. Catalytic tests revealed that the palladium complexes 4a-e are highly efficient in Suzuki-Miyaura cross-coupling reactions; their activity is equal or superior to the best PEPPSI catalysts reported to date

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N,N′-Bis(9H-fluoren-9-ylidene)benzene-1,2-diamine

Cited by 4 publications

References 7 publications

Crystal structure and DFT studies of N1,N6-Di(9H-fluoren-9-ylidene)hexane-1,6-diamine

Crystal structure and DFT studies of N1,N6-Di(9H-fluoren-9-ylidene)hexane-1,6-diamine

Structure and Stereodynamics of Aryldiimino Derivatives

N‐Heterocyclic Carbenes Functioning as Monoligating Clamps

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