Metals, activated amination

Okimato and coworkers [51] have introduced a new multicomponent photoinitiating system composed of the metal-ion-amine CCU for the polymerization of MMA (A > 300 nm). The most active system is FeS04-7H20/... 

In 1970, Monroe and Rooker(28) claimed the use of aluminum salts of acid orthophosphate esters as viscosity builders for use in fracturing fluids. The application of these materials began a new era of hydrocarbon gelling agents. Monroe(29) later claimed the use of Fe30it as a metal activator of phosphate esters and in 1971 described several other metals(30) that could be used with amine neutralization agents. Numerous metallic ionic derivatives can be used as effective "activators" or crosslinkers to prepare a gel. 

Kolb and Barth 229) synthesized oc-substituted optically active amines or amino acids (223). Again the authors employed a derivative of naturally occurring (S)-proline, namely (—)-(S)-l-dimethoxymethyl-2-methoxymethyl-pyrrolidine (221) as chiral auxiliary agent. The metalation of the amidines (160) leads to azaallyl anions homologous with (222). After alkylation and hydrolysis, the desired a-substituted amines and amino acids, respectively, are obtained with some stereoselectivity. 

The Br0nsted acid catalyzed enantioselective reduction of several methyl-aryl ketimines affords the corresponding amines in good yields and enantioselectivities (Table 4.1). The mild reaction conditions and generally good chemoselectivity of this transfer hydrogenation render this transformation an attractive and metal-free approach to optically active amines. 

The active catalytic species appears to involve a metal hydride complex, as added H2 enhances the reaction rate. Additionally, H4Ru4(CO)12 is observed during the course of the reaction and may also be used as an effective entry into the catalytic system. The oligomerization mechanism may proceed via a nucleophilic attack of the amine on a metal-activated Si-H bond, resulting in Si-N bond formation. 

Metallation of amine derivatives adjacent to nitrogen and further electrophilic substitution is a well-documented process to elaborate amines, provided that the starting amines are activated.124... 

Many other electrophiles are able to react with metalated ferrocenylalkyl amines, e.g., trimethyl borate (Fig. 4-27 a), which gives, after hydrolytic workup, compounds like (S,S)-l-(iV,iV-dimethyl-l-aminoethyl)ferrocene-2-boronic acid [106]. Important intermediates for further derivatization are the halogens. For the lithiation technique, I2 (Fig. 4-27b) [151] and BrCN [106] lead to the desired compounds, but when BrCN is used, partial substitution of the dimethylamino group by cyanide occurs (see Sect. 4.3.3.2 and Fig. 4-17). For palladated amines, Brj is applicable [152]. (i ,S)-l-Iodo-2-(iV,iV-dimethyl-l-aminoethyl)ferrocene is the starting material for catalytically active zinc compounds for the enantioselective addition of zinc alkyls to carbonyl compounds [151] (see Chapter 3 for this topic). 

The position of the heteroatom may also strongly affect the global reactivity of the molecule. Thus, ethers, esters, thioethers, and even amines, that are normally weakly reactive toward the electron, can afford cleavage at the condition to be in an activated position (benzylic or allylic) to the X group (a fast cleavage of the radical anion results in a large shift to less cathodic potentials when the global bielectronic step is considered). In a different way, the reduction of ethers and amines could be achieved only under the conditions of the Birch reaction (i.e. reduction by Li metal in amines or by a solvated electron). These conditions can be electrochemically... 

Moderate yields and low ee s were observed with an a-diazo ketone and nitrile. These authors also investigated the use of a series of metal(II) complexes, including Co, Pd, and Ni, with chiral ligands derived from optically active amines, P-diketones or 1,2-dioximes. The enantioselectivities observed with these complexes for the cyclopropanation of styrene with ethyl diazoacetate were less than 15% (mostly in a range of 0-6%). 

In order to broaden the scope of the amine-catalyzed Michael addition, Yamaguchi examined the system of amine and alkali metal salt [2]. Although amine did not promote the addition of malonate to enones, the LiCl04-Et3N catalyst turned out to be effective. Optically active amines, however, gave racemic adducts. As an extension, the (S)-proline rubidium salt, (S)-21, was developed, which possessed a cation and an amine moiety in the same molecule [2, 22]. The catalyst (S)-21 in chloroform promoted the asymmetric addition of malonate to a wide range of enones and enals as exemplified by the reaction of... 

Although occasional examples had been described earlier, the design and development of new highly active ligands for palladium gave new impetus to transition-metal-catalysed aminations. A number of relatively complex ligands were used in earlier work, but simpler versions, such as JohnPhos, have now become prominent. " These methods work well with heterocycles, for example A-arylation of indoles, using triflates, bromides and chlorides. ... 

Antimicrobial base materials formulated with metal and amine salts of anacardic acid, said to be non-irritative, have been proposed for cosmetic use [270]. It is of interest that anacardic acid and 2(E)-hexenal isolated from the cashew apple to which the pendant kernel (the external seed) is attached have been found to exhibit antibacterial activity against the Gram-negative bacterium, Helicobacter pylori, which is considered to cause acute gastritis [271]. The same compounds also inhibit the enzyme urease. 

Amcat. [Activated Metals Chem.] Amine coated catalyst... 

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