The reactions of organic azides (RN3; R = 2,6‐dimesitylphenyl, SiMe3) with bis(η5:η1‐pentafulvene)titanium complexes 1 and titanium monopentafulvene complexes Cp#Ti(η5:η1‐pentafulvene)Cl (5; #: R5 = ...H, Me) were investigated. For complexes 1, insertion of the γ‐N atom of the azide into the Ti–Cexo bond results in the formation of titanium triazenido complexes 2 in good yields. Complexes 2 undergo subsequent rearrangements in solution to titanium imido complexes 3 and 4 through release of N2. Due to a haptotropic shift of the fulvene ligands, C–C coupling of the fulvenes occurs and leads to a new chelating cyclopentadienyl allyl system. By the use of the Lewis donor 4‐chlorobenzonitrile these imido complexes are stabilized. Monopentafulvene complexes 5 directly generate chlorido‐bridged titanium imido complexes 6 by release of N2 and the fulvene ligand. These new compounds were characterized by NMR spectroscopy and single‐crystal XRD.
Reactions of η5:η1‐pentafulvene titanium complexes with organic azides result in the formation of titanium triazenido complexes by insertion of the γ‐N atom. These complexes rearrange after release of dinitrogen, haptotropic shift of the fulvene ligands, and C–C coupling of the fulvenes to titanium imido complexes with a new chelating cyclopentadienyl allyl system.
1,3-Phosphaazaallenes are heteroallenes of the type RP&z.dbd;C&z.dbd;NR′ and little is known about their reactivity. In here we describe the straightforward synthesis of ArPCNR (Ar = Mes*, 2,4,6-
t
...Bu-C
6
H
2
;
Mes
Ter, 2.6-(2,4,6-Me
3
C
6
H
2
)-C
6
H
3
;
Dip
Ter, 2.6-(2,6-
i
Pr
2
C
6
H
2
)-C
6
H
3
; R =
t
Bu; Xyl, 2,6-Me
2
C
6
H
3
) starting from phospha-Wittig reagents ArPPMe
3
and isonitriles CNR. It is further shown that ArPCN
t
Bu are thermally labile with respect to the loss of iso-butene and it is shown that the cyanophosphines ArP(H)CN are synthetically feasible and form the corresponding phosphanitrilium borates with B(C
6
F
5
)
3
, whereas deprotonation of
Dip
TerP(H)CN was shown to give an isolable cyanidophosphide. Lastly, the reactivity of ArPCNR towards Pier's borane was investigated, showing hydroboration of the C&z.dbd;N bond in Mes*PCN
t
Bu to give a hetero-butadiene, while with
Dip
TerPCNXyl the formation of the Lewis acid-base adduct with a B-P linkage was observed.
The combination of phospha-Wittig reagents with isonitriles affords 1,3-phosphaazaallenes and their diverse reactivity has been studied in detail.
An efficient conversion of readily accessible cyclic imines with acid chlorides, that are able to take part in nucleophilic aromatic substitution (SNAr) reactions is realized in a new ...three-component, one-pot reaction, giving at least tricyclic annulated quinazolinones, benzoxazinones, and benzothiazinones as a result of the employed nitrogen, oxygen, or sulfur nucleophiles, respectively. Especially in the case of quinazolinones, this convenient strategy enables the access to heterocycles of heightened diversity, which offer the development of efficient derivatizations of the elaborated heterocyclic scaffolds. In a subsequent Heck or Ullmann cyclization, further annulations to the mentioned quinazolinones can be carried out.
The mol-ecular structure of the title titanium(IV) half-sandwich complex, Ti(η5-C10H15)(η4-C21H19N)(C12H10N), shows a three-legged piano-stool geometry at the central TiIV atom, comprising of one ...penta-methyl-cyclo-penta-dienyl ligand, one bidentate ketimine ligand in an η4-coordination mode and one monodentate di-phenyl-amide ligand. Except for van der Waals forces, there are no significant inter-molecular inter-actions in the crystal.
Isolable Phospha- and Arsaalumenes Fischer, Malte; Nees, Samuel; Kupfer, Thomas ...
Journal of the American Chemical Society,
03/2021, Letnik:
143, Številka:
11
Journal Article
Recenzirano
The combination of (AlCp*)4, a source of monomeric :AlCp* at elevated temperatures, with DipTerPnPMe3 (Pn = P, As), so-called pnicta-Wittig reagents, at 80 °C cleanly gives the pnictaalumenes ...DipTerPnAlCp* with polarized Pn–Al double bonds and intramolecular stabilization through interactions of Al with a flanking aryl group of the terphenyl substituent on Pn. In contrast, using MesTerPPMe3, the reaction with 2 equiv of :AlCp3t or :AlCp* afforded the three-membered 2π-aromatic ring systems MesTerP(AlCp x )2 (x = 3t, *).
Intermolecular hydroaminoalkylation reactions of alkynes with secondary amines, which selectively give access to allylic amines with E configuration of the alkene unit, are achieved in the presence ...of titanium catalysts. Successful reactions of symmetrically substituted diaryl‐ and dialkylalkynes as well as a terminal alkyne take place with N‐benzylanilines, N‐alkylanilines, and N‐alkylbenzylamines.
Allylic amines are directly formed from secondary amines and alkynes in the presence of highly active titanium catalysts. The corresponding hydroaminoalkylation reactions, which take place by C−H bond activation at sp3‐centers in the α‐position to a nitrogen atom, can be achieved with internal and terminal alkynes, and best results are obtained with N‐benzylaniline derivatives.
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