Amines reaction with diazo compounds

By analogy with the rhodium carbene intermediate proposed in the C H insertion reaction with diazo compounds, C— H amination is believed to proceed via a rhodium nitrene species, although such an intermediate has never been characterized. However, as chiral dimeric rhodium complexes lead to the formation of enantioen-riched amination products, it suggests that the metal center is closely associated with the reactive nitrogen during the C—H insertion step. Both a rhodium nitrene or rhodium phenyliminoiodinane species may be involved (Figure 5.2). 

The reaction of diazo compounds with amines is similar to 10-15. The acidity of amines is not great enough for the reaction to proceed without a catalyst, but BF3, which converts the amine to the F3B-NHR2 complex, enables the reaction to take place. Cuprous cyanide can also be used as a catalyst. The most common substrate is diazomethane, in which case this is a method for the methylation of amines. Ammonia has been used as the amine but, as in the case of 10-44, mixtures of primary, secondary, and tertiary amines are obtained. Primary aliphatic amines give mixtures of secondary and tertiary amines. Secondary amines give successful alkylation. Primary aromatic amines also give the reaction, but diaryl or arylalkyl-amines react very poorly. 

In contrast to the epoxides, preparative routes to the aziridines are fairly evenly split between the [C=N + C] and the [C=C + N] routes. Among contributions in the former category, aziridine carboxylate derivatives 110 can be prepared through the lanthanide-catalyzed reaction of imines with diazo compounds, such as ethyl diazoacetate (EDA). In this protocol, iV-benzyl aryl aldimines and imines derived from aromatic amines and hindered aliphatic aldehydes are appropriate substrates <99T12929>. An intramolecular variant of this reaction (e.g.. Ill —> 112) has also been reported <990L667>. 

Compared to diazonium salts, diazo compounds are generally much less reactive towards nucleophiles than towards electrophiles. As a result of this azo coupling reactions of diazo compounds are the exception rather than the rule. Electron withdrawing substituents on the diazo carbon increase the reactivity towards nucleophiles. Consequently the ability to undergo azo coupling reactions increases from diazomethane to diazocarbonyl- and 2-diazo-l, 3-dicarbonyl compounds. Among the earliest reactions known were those with cyanide and sulfite ions Tertiary phosphines, as opposed to amines, can form stable addition complexes with diazoalkanes probably due to the ability of phosphorus to stabilize the betaine with its empty d orbitals (6). 

Intramolecular Reaction of Diazo Compounds with Tertiary Amines, Ethers and Thioethers... 

Cyclization of diazopyrazoles 9 is also possible by a two-step process, firstly by reaction of diazo compounds 9 with primary amines followed by cyclization of the formed triazenes 18 with phosgene (X = Y = Cl), diimidazolyl ketone (X = Y = imidazolyl) or trichloromethyl chloroformate (X = Cl Y = CC1,).36... 

PHENYLTRIDECANE (123-02-4) CjsHji Combustible liquid (flash point 230°F/110°C). Violent reaction with bases, amines, amides, and inorganic hydroxides and with diazo compounds. Incompatible with nitric acid, strong oxidizers. On small fire use water spray, dry chemical powder (such as Purple-K-Powder), alcohol resistant foam, or CO2 extinguishers. PHILOSOPHERS WOOL (1314-13 -2) see zinc oxide. 

In coupling reactions, the diazo compound formed above is reacted with the coupling components, such as aromatic amines, phenols, and naphthols. The reaction is as follows ... 

Although the CRI reaction of diazo compounds 17a and 17b yielded the pentacyclic intermediates 20 and 28, further alkylation to form a C8 quaternary carbon center was unsuccessful under various conditions. This appears to be due to steric hindrance by the bulky benzyl and cumyl groups after protection of the free amine. To improve the CRI reaction. Dr. Jun Yang modified the diazonamide substrate by replacing the amide functionality (17) with an ester... 

The same group has reported the enantioselective electrophilic 7-amination of a,(3-unsaturated dinitriles and nitrile esters through allylic C-H activation with a cinchona alkaloid catalyst [56]. Thus (Scheme 11.15), the reaction of the corresponding unsaturated nitrile with diazo compound B0C2N2 in the presence of 10 mol% of catalyst 31 afforded the 7-aminated nitrile adducts in good yields (65-90%) and excellent enantioselectivity (86-99% ee). 

The first multicomponent organocatalytic asymmetric aziridination reaction was reported very recently by Wulff et al. They synthesized chiral aziridine carboxyhc ester 174 with excellent yield and stereoselectivity starting from aromatic or aliphatic aldehyde 171, primary amine 172, and diazo compound 173 (Scheme 40.34). The in MtM-generated... 

The direct organocatalyzed a-amination reaction has been also applied to 1,3-dicarbonyl compounds and related compounds. So, the reaction of aryl cyano-acetates (28, R =aryl and heteroaryl) with diazo compounds 18 catalyzed by tertiary amine 30 (Scheme 4.5) gave the expected products 29. The enantioselectivity of the reaction seems to be dependent on the bulkiness of the diazo compound used. The more bulkier compound 18, the higher enantioselectivity was obtained. This sentence was also true for the ester moiety in 28. The presence of substituents at the aryl group at either meta- or orf/to-position did not have any accountable influence on results. Only a slight decrease in the enantioselectivity was accomplished with... 

Azo Coupling. The coupling reaction between an aromatic diazo compound and a coupling component is the single most important synthetic route to azo dyes. Of the total dyes manufactured, about 60% are produced by this reaction. Other methods iaclude oxidative coupling, reaction of aryUiydraziae with quiaones, and oxidation of aromatic amines. These methods, however, have limited iadustrial appHcations. 

Z)-compounds are formed in reactions with hydroxide, methoxide, cyanide, and sulfite ions, whereas (ii)-compounds are formed in most reactions with amines (formation of triazenes) and with diazo coupling components such as phenols and aromatic tertiary amines. 

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