Hydrozirconation-amination

The amination of styrene, however, led to two products (1-phenyl-1-ethylamine and 2-phenyl-l-ethylamine) in a 1 3 ratio [113], indicating that the hydrozirconation was not completely regioselective [114,115]. Since it is well known that hydrozirconation of trisubsti-tuted alkenes places zirconium at the least hindered carbon of the chain by a process involving zirconium migration, this class of alkenes was not investigated [5,116], On the other hand, hydrozirconation/amination of 3-methyl-l,2-butadiene gave an allylic amine. Reaction of the latter could either occur at the terminal carbon or proceed with... 

Herein is described how organoboron and additionally organozirconium compounds have proved to be valuable precursors to a variety of amines via hydrobora-tion-amination, or less frequently hydrozirconation-amination. 

On the other hand, hydrozirconation-transmetalation to zinc, when carried out in THF, can be used to prepare allylic amines. When carried out in CH2CI2, however, a different reaction pathway is followed (Scheme 24). Even more, with a different order of introduction of the reagents, it is possible to obtain diastereoselectively homoaUyhc amines instead of the expected aminocyclopropanes. ... 

Zirconium complexes, generated in situ by addition of HZrCp2Cl to alkenes, can be animated with <9-(mesitylenesulfonyl)hydroxylamine an example is shown in Eq. 41.116 When the initial hydrozirconation is not regioselective, as with styrene, mixtures of amines are formed. A reaction that permits animation at the tertiary carbon in a similar substrate is discussed below (Eq. 49). 

Hydrozirconation with Cp2Zr(CI)H can be followed by Michael addition, or by reaction with O-mesitylsulfonyl hydroxylamine (MSH) to prepare amines (see 1st edition). 

Novel tetrahedral boronate complexes have been prepared as potential ligands for affinity chromatography either from the amination (LiN(TMS)2) of a-haloalkylboronates followed by A-acetyl-ation (i.e., (132)) or, alternatively, from the a-iodo derivatives and acetamidine (i.e., (133)) (Scheme 17). The 1,3,2-dioxaborinanes proved to be less stable than the pinanediol derivatives to silica gel. "B NMR as well as other data confirmed their chelated nature (e.g., (132) d 6.8) <92JOM(43i)255>. Spiroborates (e.g. (134)) have also been prepared from boric acid, diols, and enolizable 1,3-dicarbonyl compounds <86JPR755>. Vinylzirconocenes (135) are converted to vinylboronates (136) with chloroboranes <910M3777>. The hydrozirconation of 5-vinylboronates (137) produces the mixed... 

Primary amines. Hydrozirconation of 1 -alkenes followed by reaction 0-(mesitylenesulfonyl)hydroxylamine provides primary amines (10 examples, 62-88%). 

Scheme 8). This report described the hydrozirconation of dimethylmalono-nitrile " to form bis-metalloimine 34. A number of electrophiles can react with 34, though from our perspective the most compelling reaction was the coupling with pivaloyl chloride to form bis-acylimine 35 in 94% yield. Thus, we envisioned a multicomponent reaction in which a nitrile, an acid chloride, a metal hydride, and an alcohol could combine in a single reaction flask to form an W-acyl aminal. 

Hydrozirconation of functionalized alkyne 8 in CH2C32 with the Schwartz reagent followed by in situ transmetallation to Me2Zn and addition of N-diphenyl-phosphinoylimine 15 provides the functionalized trans-aminocydopropane 16 in 60% yield [15]. The cydopropane formation can be rationalized by the formation of a transient zinc-carbenoid species from CH2CI2, which subjected the intermediate allylic amine derivative to an efficient Simmons-Smith-type cydopropanation. 

Chloro-l-pentene 22 also undergoes the hydrozirconation reaction and can be either trapped with O-(mesitylsulfonyl) hydroxylamine (MSH) [21] 23 or with 2-chlorotetrahydropyran 24 [22] to lead to the corresponding primary amine 25 and ether 26, respectively, in good isolated yield (Scheme 12.18). 

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