Silicon-nitrogen bond synthesis

A less explored area of transition metal catalysis involves bond formation between Group 14 elements and nitrogen. In direct analogy to previously discussed areas of research, silicon-nitrogen bonds can be formed by dehydrocoupling, hydrosilylation, and dehydrogenative silylation. The compounds produced are valuable for use in organic synthesis or as polymer precursors to silicon nitride ceramics. 

Compounds containing the Si-N-P linkage combine the structural and stereochemical diversity of phosphorus with the reactivity of the silicon-nitrogen bond. Indeed, much of the derivative chemistry and synthetic potential of these compounds, especially the (silylamino)phosphines such as (Me3Si)2NPMe2, is based on this difunctional character. We report here a general, "one-pot" synthesis of (silylamino)phos-phines and describe their use in the preparation of several types of phosphorus-containing materials. 

Most of the reactions and properties of 1-substituted imidazoles have been discussed earlier in this review. Apart from the utilization of the readily removable benzyl substituent in synthetic procedures leading to 2-substituted imidazoles, perhaps the mostexciting advances have stemmed from the reactions of the 1 -acylimidazoles (imidazolides) which are extremely reactive in such nucleophilic reactions as hydrolysis and alcoholysis.12 The use of such compounds as N,N -carbonyl-diimidazole in peptide synthesis is now commonplace. The silicon-nitrogen bond in N-trimethylsilylimidazoles is also extremely reactive, so reactive that it is attacked by a-halogenocarboxylic esters.361... 

The synthesis of compounds with a silicon—nitrogen bond are well known hy the nucleophilic suhstitution reaction of chlorosi-lane using alkali metal amide or amine in the presence of a HCl scavenger (1). 

As mentioned in this chapter, in recent years much progress has been made in the chemistry of silicon-chalcogen multiple bonds. For silicon-sulfur doubly-bonded compounds, we have now several isolated examples, both kinetically stabilized and thermodynamically stabilized. Furthermore, there have been reports of the synthesis and characterization of stable compounds with silicon-nitrogen double bonds (i.e. silanimines or iminosilanes) as well as their heavier group 15 element analogues such as phosphasilenes and arsasilenes. 

Amino, alkoxy, and aryloxy polyphosphazenes are typically prepared by nucleophilic displacement reactions of poly(dihalophosphazenes). Analogous reactions with organometallic reagents, however, result in chain degradation and cross linking rather than in linear, alkyl, or aryl substituted poly(phosphazenes). The thermolysis of appropriate silicon-nitrogen-phosphorus compounds can be used to prepare fully P—C bonded poly(organophosphazenes). The synthesis of two of these materials and their Si—N—P precursors is described here. 

This represented the first synthesis of an organosilicon derivative with a formal silicon-nitrogen triple bond. 

SiUcon-carbon and silicon-nitrogen multiply bonded compounds 899 method for the synthesis of silylenes ". Silene 258 is not obtained (equation 64). 

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