Addition reactions imidoyl halides

M. F. Lappert, and A. J. Oliver, A Three-Fragment Oxidative Addition Reaction as a Route to Transition Metal Carbene Complexes Imidoyl Halides and Rhodium(I) Compounds as Precursors for Rhodium(III) Carbenes, J. Chem Soc., Chem. Comm. 1972, 274-275. 

Imido esters, like imidoyl halides, can be considered as activated nitriles which are formed during alcohol-catalyzed trimerization reactions of nitriles, but they cyclotrimerize even more easily to the 1,3,5-triazines. The reaction can be catalyzed by an additional acid276 278,481 or carried out under high pressure.280... 

The solvolysis can be autocatalytic because the generated acid could catalyze further reaction. In addition to water, a great variety of nucleophiles, such as OR , SH , SR , NR , CN , COO , N , etc., have been reacted with the imidoyl halide system and the results obtained from several main groups of imidoyl halides are summarized in Table II. 

A variety of other reactions of imidoyl halides are described in the literature, for example addition reactions to the C=N double bond, the Michaelis-Arbuzov reaction, Grignard reactions, and reduction to the corresponding azomethine. The latter is another useful method for the synthesis of aldehydes. 

The reactions of carbonimidoyl dihalides can be divided into nucleophilic substitution reactions, whereby the halo groups are replaced stepwise by other nucleophiles, and addition reactions. The substitution reactions are often accompanied by elimination, depending upon the stability of the formed imidoyl derivatives. For example, the monosubstitution products can eliminate hydrogen halide, alkyl halide, or sulfenyl chloride, i.e.,... 

Iminium halides are intermediates in the hydrolysis of nitriles and in a variety of chemical reactions. For example, in the Ritter reaction addition of a nitrile or hydrogen cyanide to a carbonium ion occurs, leading to the intermediate formation of a nitrilium salt. Nitrilium salt intermediates have also been postulated in the Schmidt reaction and in the Beckmann rearrangement, provided the latter was performed in concentrated sulfuric acid. However, since we are predominantly concerned with imidoyl halides, these reactions are not discussed in this monograph. 

While substituted succinonitriles also add hydrogen bromide to produce the corresponding imidoyl halides addition of hydrogen chloride to succinonitrile gives rise to the formation of different reaction products ( ). 

In the cyclic series imidoyl halides are reported only for five-, six-, and seven-membered ring systems. However, it was demonstrated recently that 2,2-dichloroaziridines, which are obtained by addition of dichloro-carbene to C=N double bond compounds, react as iminium chlorides. The synthetic methods for the cyclic imidoyl halides are similar to those used for the preparation of the linear species. Therefore, emphasis is focused on the reactions of cyclic imidoyl halides rather than on their synthesis. The organization of this chapter also differs from that of the previous chapters because it is based on ring size rather than on the difference attributable to substituents attached to the C=N double bond system. 

---