Dis-azo compounds

Based on his previous work describing the catalytic double addition of di-azo compounds to alkynes [59], Dixneuf used Cp RuCl(cod) and worked out a simple synthesis of alkenyl bicyclo[3.1.0]hexane derivatives 75 from enyne precursors 74 (Scheme 33). The catalytic cycle starts with the formation of... 

Di-azo Compounds.—Contrasted with the azo compounds we have another group known as the di-azo compounds. As the name indicates these also contain two nitrogen atoms and these nitrogens are also directly linked to each other, but only one nitrogen atom is linked to a benzene ring. ... 

Amino azo compounds are in general yellow or brown crystalline substances insoluble or difficultly soluble in water, but soluble in alcohol or ether. They are basic compounds readily forming salts which usually possess a distinctly different color from that of the free bases. As amino compounds they are able to be diazotized and converted into still more complicated azo compounds in which two azo groups are present in the molecule and which are known as dis-azo compounds. 

When the diazotization of the meta phenylene diamine is carried further so that both amino groups are diazotized a double diazo compound or tetrazo compound is obtained and this couples with two molecules of meta-phenylene diamine yielding a double azo or dis-azo compound. 

Bismarck Brown.—The dis-azo compound obtained meta-diamino benzene dis-azo benzene meta-di-amino benzene is a dye known as Bismark brown, though the dye is probably a mixture of the dis-azo compound and tri-amino azo benzene. With the exception of aniline yellow or amino azo benzene it was the first azo dye to be made. It was first prepared by Martins in 1864, and first made as a dye in 1866. 

This reaction gives epoxides in good yield and returns the corresponding sulfide. In order to render this process catalytic in sulfide, it is necessary to find conditions for converting the sulfide back into the sulfur ylide in the presence of the carbonyl compound. Two procedures have been developed to achieve this (i) sulfide alkylation in the presence of base and (ii) reaction of a sulfide with a di-azo compound in the presence of a suitable metal catalyst. These methods are discussed in more detail in this chapter. 

Dihydro-2-isopropyl-3.6-dimethoxypyrazine, a bis(lactim)ether, is converted into the 5-di-azo compound 1 by lithiation and diazo group transfer. The intermediate diazo compound reacts at room temperature with olefins such as cyclohexene to produce the cyclopropane derivatives with excellent diastereoselectivity . The derivative from cyclohexene is hydrolyzed by acid treatment to give methyl 7-cv(cfo-aminobicyclo[4.1.0]hcptane-7-carboxylate. The bis(lac-tim)ether diazo compound 1 is also involved in an exceptional asymmetric [2 + 1J cycloaddition producing cnantiomerically pure cyclopropenc derivatives4. Thus, reactions of the diazo compound with monosubstituted alkynes afford the spiro compounds as one diastereomer. Hydrolytic removal of the auxiliary and protection of the amino group provides enantiomerically pure methyl l-amino-2-arylcyclopropene-l-carboxylates in moderate overall yield. 

Oxidation of Amines to Aldehydes Imines, Amides, and Di-azo Compounds. jhe oxidation of amines by Mn02 can lead to various products according to the structure of the starting material. Thus the formation of imines (eq 44), formamides (eqs 45 and 46), and diazo compounds (eq 47) P have all been described. 

M. Regitz, Phosphoryl Di azo compounds, in Chemistry ofDiazpnium and Diazo Groups, Chapter 17, Wiley, 1978. 

The Hammett eorrelation study was carried out with a series of substituted di-azo compounds 1 (X=/7-N02,/7-Br, j-MeO,p-Ph, w-Me,p-MeO and H) with different rhodium(II) catalysts (Rh2(OAc)4, Rh2(Ooct)4, Rh2(tfa)4). The relative rate (A ei) constants were calculated for each substituted diazo phenylaeetate (Arei(x) = obs(x) / obs(H))- The obs(x) values were obtained for each substituent aeeording to pseudo-first order Eq. 21.1. The data are collected in Table 21.1. 

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