Amination hydro

Azoniaspiro[4.8]tridecane 129 was formed from the substituted triazacyclononane 128 (X = OMe) on standing in methanol for ten days (Scheme 15) <2000AJC791 >. It was precipitated as the tetraphenylborate salt 130 (X = BPli, ) since attempts to isolate the methoxide derivative by evaporation of the solvent led to elimination reactions yielding a mixture of triazacyclononane 131 and allene 132 in the ratio of 1 10. Re-dissolution of these allows further hydro-amination reactions to occur. Precipitation and analysis of their tetraphenylborate salts suggested the products to be 130-132 in a ratio of 1 8 1. Owing to their chemical similarities these components were not isolated. 

The secondary amide can also attack intramolecularly an additional ester function to form a cyclic imide, although only in moderate yields [67], Finally, the palladium-catalysed intramolecular reaction with an alkyne, resulting in a hydro-amination of the latter, will be described later (Fig. 17) [68]. 

The (h and m.-mirohmzoic, dm, on electrolysis, deja themselves like the free acids Jatfermann). The latter mv tigutor,3 by preparing the benzylidene compound by the mm method, proved the intermediate formation of the hydros amine phase in the reduction of the m-arid. 

Scheme 4. Catalytic cycle, structure of the transition state TS in the insertion step, different cycloaliphatic amines as reaction products, and turnover numbers in mol sub-strate/(mol Ln) per h, for the organolanthanide-catalyzed intramolecular hydro-amination of a,w-aminoolefins (a) with La(C5Mes)2N(SiMe3)2, and (b) with Nd(Me2Si(C5Me4)2)N(SiMe3)2 as pre-catalyst.

Constrained-geometry complexes of the type [Me2Si(C5Me4)(NBut)]An(NRR1)2 (An = Th, U R = R1 = Me R = Me, R1 = Et R = R1 = Et) have been reported to be effective precatalysts for intramolecular catalytic hydro-amination/cyclization of aminoalkenes and aminoalkynes.55... 

As already mentioned, there has been significant progress in the development of chiral catalysts for asymmetric hydroamination reactions over the last decade. However, significant challenges remain, such as asymmetric intermolecular hydro aminations of simple nonactivated alkenes and the development of a chiral catalyst, which is applicable to a wide variety of substrates with consistent high stereochemical induction and tolerance of a multitude of functional groups as well as air and moisture. Certainly, late transition metal based catalysts show promising leads that could fill this void, but to date, early transition metal based catalysts (in particular, rare earth metals) remain the most active and most versatile catalyst systems. 

Horrillo Martinez, P. (2008) New Catalysts for Base Catalysed Hydro amination Reaction of Olefins, PhD thesis, Universitat Erlangen Nurnberg. 

Hydroamination. On exchanging two of the Et2N groups of the title reagent to A-(2,6-diisopropylphenyl)benzamido residues, a precatalyst for anti-Markovnikov hydro-amination of 1-alkynes to form aldimines is readily obtained. 

Photochemical transformation of HFu anions aligned by imidazolium cations occurs via a topotactic fashion. On the other hand, under heating of (HFu )(Im ) at 190 °C produces an unexpected solvent-free hydro-amination reaction in the solid state with very near quantitative yield (J ,5)-2-(li -imidazol-l-yl)succinic acid. This product, to the best of our knowledge, represents the first example of a hydroamination product obtained via a solvent-and-catalyst-free process (Scheme 15). 

The coordinated phosphinoalkyne of complex 204 undergoes a hydro-amination reaction with aniline affording iminophosphine complex (5p)-205 and its Rp diastereomer (50% de towards the Sp epimer, determined by NMR... 

Cyclopentadienyl complexes of lanthanoids can be used as catalysts for the hydro-amination/cyclization of aminoolefines [90], the hydroformylation of olefines [89, 135], the cyclization of alkynes [68] and other processes. 

Intramolecular asymmetric hydroamination (hydro-amination/cyclization)... 

Hultzsch KC. Transition metal-catalyzed asymmetric hydro-amination of aUcenes (AHA). Adv. Synth, Catal. 2005 347 (2-3) 367-391. 

Fig. 3 Selected examples of achiral, non-metallocene rare earth metal-based catalysts for hydro-amination of aminoafkenes [74, 89, 91, 92, 94]...

The double bond in vinyl arenes is activated as a result of its conjugation to the aromatic ring system. Hence, vinyl arenes generally react more smoothly in hydro-amination reactions in comparison to simple, unactivated alkenes, especially in intermolecular processes. 

Contrary to simple aliphatic-substituted alkenes, the metal-catalyzed hydro-amination of vinyl arenes proceeds usually with high anti-Markovnikov selectivity to give p-phenethylamine derivatives (Fig. 12). This reversal of regioselectivity may be explained with the alkene insertion step proceeding through the sterically more encumbered transition state which is favored due to attractive metal-arene interactions and resonance stabilization of the benzyl carbanion. The same selectivity pattern is observed for alkali [40] and alkaline earth [154, 155] metal catalysts and is also explained by metal-aryl interactions as shown by DFT-calculations [40]. 

The development of group-4-metal-based catalysts for intramolecular hydro-amination of aUcenes has also led to several advanced systems for asymmetric hydroamination (Fig. 19). Most group 4 metal catalyst systems exhibit inferior reactivity and substrate scope (Table 19) in comparison to most rare earth metaland alkaline earth metal-based catalyst systems. They typically require high catalyst loadings and elevated reaction temperatures. However, the recent development of zwitterionic zirconium catalysts with significantly improved reactivities and selectivities [60, 118] promises to close this gap. 

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