General Considerations in Organic Synthesis. Preparation of Starting Materials

GENERAL CONSIDERATIONS IN ORGANIC SYNTHESIS. PREPARATION OF STARTING MATERIALS 

What effect can a transition metal have on double bonds According to the metal and the circumstances, it can activate, deactivate, or protect the double bonds for electrophilic or nucleophilic attack, resolve geometric or optical isomers, direct attack stereospecifically, and aromatize or dearomatize appropriate systems. This is a list of achievements often difficult or impossible to reach by standard organic-type reactions alone. 

Another important question to the organic chemist is the ease of preparing and handling transition metal n complexes. Usually there are no unfamiliar handling properties, although there is the usual emphasis on the beneficial use of pure solvents and the exclusion of oxygen. Even these precautions are often not necessary. 

Many of the resulting complexes can be chromatographed, distilled, or crystallized, and standard methods such as thin layer (tic) and gas-liquid (glc) chromatography are frequently applicable. Mass spectrometry and nmr spectra are very useful for defining structures. For key references to the characterization of organometallic compounds by ir, nmr, mass spectrometry, and glc, see Tsutsui (1971), Maddox et al. (1965), Bruce (1968), Lewis and Johnson (1968), and Guiochon and Pommier (1973). 

Removal of the Fe(CO)3 group is normally achieved by treating the complex with an oxidizing agent such as ceric ammonium nitrate, ferric chloride, or cupric chloride, usually at between 0° and room temperature, in a solvent such as aqueous acetone or ethanol. In some cases, trimethylamine N-oxide 

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