Characteristic of carbonyl compounds

In addition to reactions characteristic of carbonyl compounds, Fischer-type carbene complexes undergo a series of transformations which are unique to this class of compounds. These include olefin metathesis [206,265-267] (for the use as metathesis catalysts, see Section 3.2.5.3), alkyne insertion, benzannulation and other types of cyclization reaction. Generally, in most of these reactions electron-rich substrates (e.g. ynamines, enol ethers) react more readily than electron-poor compounds. Because many preparations with this type of complex take place under mild conditions, Fischer-type carbene complexes are being increasingly used for the synthesis [268-272] and modification [103,140,148,273] of sensitive natural products. 

Sections 8.3.1-8.3.3 present the use of iron, mthenium and osmium carbonyls, respectively, in the preparation of supported catalysts. Over non-inert supports, besides the characteristics of carbonyl compounds, the reactivity of the surface and that of the specific element, mainly related with its redox properties, will be covered for each metal. 

This simple model allows us to rationalize the major t) es of reactions that are characteristic of carbonyl compounds reacting from an n,n excited state ""... 

What are the spectral characteristics of carbonyl compounds In H NMR spectroscopy, the formyl hydrogen of the aldehydes is very strongly deshielded, appearing between 9 and 10 ppm, a chemical shift that is unique for this class of compounds. The reason for this effect is twofold. First, the movement of the ir electrons, like that in alkenes (Section 11 ), causes a local magnetic field, which strengthens the external field. Second, the charge on... 

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