Highly selective mono-n-benzylation and amidation of amines with alcohols or carboxylic acids using the [Ph.sub.2]PCI/[I.sub.2]/imidazole reagent system

Chlorodiphenylphosphine, imidazole, and molecular iodine in refluxing dichloromethane are used for the efficient preparation of amides under mild reaction conditions. This reagent system also shows excellent selectivity for mono-Nalkylation of amines with alcohols. In this system, the resulting phosphorus byproduct (diphenylphosphinic acid) is easily removed by extraction using an aqueous basic solution in the workup processes, which avoids the tedious and time-consuming chromatographic methods. Key words: benzylation, amidation, imidazole, amine, alcohol, carboxylic acid, chlorodiphenylphosphine, iodine. On a utilise un melange de chlorodiphenylphosphine, d'imidazole et d'iode moleculaire dans le dichloromethane au reflux pour preparer des amides d'une facon efficace, dans des conditions douces. Ce systeme de reactifs presente aussi une bonne selectivite pour la mono-N-alkylation d'amines avec des alcools. Dans ce systeme, il est facile d'eliminer le sous-produit phosphore, l'acide diphenylphosphinique, par extraction du melange reactionnel a l'aide d'une solution basique aqueuse qui evite les methodes chromatographiques lentes et ennuyeuses. Mots-cles : benzylation, amidation, imidazole, amine, alcool, acide carboxylique, chlorodiphenylphosphine, iode.
Introduction For many years, phosphines as reagents or catalysts have been employed for various organic transformations. Among these, soluble triphenylphosphine (TPP) has found significant attention, and several applications of this [...]