Alcohols can be temporarily converted into carbonyl compounds by the metal-catalysed removal of hydrogen. The carbonyl compounds are reactive in a wider range of transformations than the precursor alcohols and can react in situ to give imines, alkenes, and a-functionalised carbonyl compounds. The metal catalyst, which had borrowed the hydrogen, then returns it to the transformed carbonyl compound, leading to an overall process in which alcohols can be converted into amines, compounds containing C À C bonds and b-functionalised alcohols.

Amongst the many ways of constructing the amide bond, there has been a growing interest in the use of metal-catalysed methods for preparing this important functional group. In this tutorial review, highlights of the recent literature have been presented covering the key areas where metal catalysts have been used in amide bond formation. Acids and esters have been used in coupling reactions with amines, but aldehydes and alcohols have also been used in oxidative couplings. The use of nitriles and oximes as starting materials for amide formation are also emerging areas of interest. The use of carbon monoxide in the transition metal catalysed coupling of amines has led to a powerful methodology for amide bond formation and this is complemented by the addition of an aryl or alkenyl group to an amide typically using palladium or copper catalysts.

The alkylation of amines by alcohols has been achieved using 0.5 mol % [Ru(p-cymene)Cl(2)](2) with the bidentate phosphines dppf or DPEphos as the catalyst. Primary amines have been converted into secondary amines, and secondary amines into tertiary amines, including the syntheses of Piribedil, Tripelennamine, and Chlorpheniramine. N-Heterocyclization reactions of primary amines are reported, as well as alkylation reactions of primary sulfonamides. Secondary alcohols require more forcing conditions than primary alcohols but are still effective alkylating agents in the presence of this catalyst.

Catalysts make alcohols more reactive by taking away hydrogen to create carbonyl compounds and then returning the hydrogen to the final products.