Olefins arylamination

Polyelectrolytes and soluble polymers containing triarylamine monomers have been applied successfully for the indirect electrochemical oxidation of benzylic alcohols to the benzaldehydes. With the triarylamine polyelectrolyte systems, no additional supporting electrolyte was necessary [91]. Polymer-coated electrodes containing triarylamine redox centers have also been generated either by coating of the electrode with poly(4-vinyltri-arylamine) films [92], or by electrochemical polymerization of 4-vinyl- or 4-(l-hydroxy-ethyl) triarylamines [93], or pyrrol- or aniline-linked triarylamines [94], Triarylamine radical cations are also suitable to induce pericyclic reactions via olefin radical cations in the form of an electron-transfer chain reaction. These include radical cation cycloadditions [95], dioxetane [96] and endoperoxide formation [97], and cycloreversion reactions [98]. 

Doyle, M. P., Siegfried, B., Elliott, R. C., Dellaria, J. F., Jr. Alkyl nitrite-metal halide deamination reactions. 3. Arylation of olefinic compounds in the deamination of arylamines by alkyl nitrites and copper(ll) halides. A convenient and effective variation of the Meerwein arylation reaction. J. Org. Chem. 1977, 42, 2431-2436. 

Hegedus developed an olefin amination process that generates indoles by intramolecular nucleophilic attack of substituted amines on allylarenes (Equation 11.27). In this process, an N-tosyl arylamine attacks the coordinated olefin of an allyl group in the ortho position of the aniline, and p-hydrogen elimination generates a tautomer of indole and a reduced palladium complex. This reduced complex is then re-oxidized by quinone to regenerate the starting palladium(II), and the product tautomerizes to the final indole product. This cycle was one of the earliest catalytic olefin aminations. 

Hydroaminations of alkenes have proven to be more challenging to develop than other hydroamination reactions, although some of the first hydroaminations were additions to alkenes. In 1971 Coulson reported the addition of secondary amines to ethylene catalyzed by RhClj. Additions of amides to ethylene and propylene have been published more recently by Widenhoefer, as shown in Equation 16.57, and the addition of aniline to norbomene was published by Milstein and Casakiuovo. Although the turnover numbers for the addition of aniline to norbomene were low, several important mechanistic findings resulted from this work were presented in Chapter 9 and are reviewed in Section 16.5.3.3. Additions of amines to ethylene, propylene, and norbomene are less complicated than additions to higher olefins because these alkenes cannot undergo isomerization to a less reactive internal olefin. Nevertheless, Brunet has reported additions of arylamines to ethylene and hexene catalyzed by platinum halides with acid additive in anionic liquid (Equation 16.58). ... 

The bulk of the studies on intramolecular hydroamination of alkenes catalyzed by lanthanide complexes have been conducted using lanthanocene complexes or half-sandwich lanthanide complexes. The prototypical cyclizations of aminoalkenes to form five- and six-membered rings are shown in Equation 16.61. These reactions occur with exclusive Markovnikov selectivity. These reactions have also been conducted using arylamines, as shown in Equation 16.62. The intramolecular reactions of amines catalyzed by certain lanthanide complexes occur with 1,1- and 1,2-disubstituted olefins (Equation 16.63), although such reactions require high temperatures. 

The oxidative aminations of olefins have been reported in parallel witfi the oxidations of olefins witii alcohols, phenols, and carboxylic acids. These reactions are generally conducted with amides or imides amines are tfiought to be protonated by the acidic medium or to bind the metal center too tightly to allow for the catalytic chemistry to occur. Some exceptions noted below have been observed with arylamines or with rhodium catalysts. These oxidations have been conducted botfi intermolecularly and intramolecularly The oxidations have been conducted with benzoquinone, with copper, or with alone as the... 

Some of the earliest oxidative aminations of olefins were reactions of lactams with electron-poor olefins reported by Murahashi. Examples of these reactions conducted with tiie combination of Oj and CuCl with HMPA as additive are shown in Equation 16.115. This type of oxidative amination of olefins can also be conducted with N-alkyl arylamines, as demonstrated by Hegedus (Equation 16.116). Like the oxidations of acrylates with alcohols, these reactions occur at the p-carbon of the acrylate. 

Intramolecular oxidative aminations of olefins have alsobeen studied, and many of these intramolecular processes were observed prior to the analogous intermolecular variants. The oxidative aminations of alkenes with arylamines and arylamine derivatives catalyzed by palladium complexes were shown by Hegedus to form indoles (Equation 16.120). These reactions were conducted with orf/io-allylaniline and ort/zo-allylaniline derivatives as substrate, Pd(NCMe)jCl2 as catalyst, and benzoquinone as oxidant. Intramolecular reactions of N-tosylated aliphatic amines were reported by Larock. ° For example, the tosylamide in Equation 16.121 imdergoes cyclization in high yield in the presence of dioxygen with Pd(OAc)j as catalyst in DMSO. A related reaction (Equation 16.122) was reported recently in toluene solvent with added pyridine. ... 

The use of arylamines in the Pd"-catalysed coupling with olefins has been reported. This modification of the classical Heck procedure further extends the utility of the method. A study of the regiochemistry of the cycloaddition of substituted trimethylenemethanepalladium complexes is necessary if they are to be generally adopted in synthesis. Reaction of cyclopentenone with a methyl-substituted trimethylenemethane species afforded a single stereoisomeric product, which was converted to a precursor of the natural product chrysomelidial (Scheme 24). Since previous work on the unsubstituted system suggested a... 

Fig. 2.66. Examples of products from oxidative addition reactions of different substrates to Os3(CO)i2 (a) Ethylene, (b) cyclic olefine (c) benzene (d) H2S (e) arylamine (f) aniline (g) alkyl or aryl phosphine...

Aminomercurated olefins also undergo mercury-lithium transmetallation to give the dianions (8), which react with a variety of electrophiles to give substituted secondary arylamines (Scheme 15). o-Alkylated arylamines are the products of the reaction of arylaminodivinylboranes with acetylene derivatives."... 

Scheme 35.16 Olefin arylamination selectivity modulated by a combination of organocatalysts.

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