Reaction multiple-component condensation

Wong and co-workers [22] also applied the methodology in the preparation of a library of neomycin B mimetics (Fig. 6). Two libraries were prepared by a multiple-component condensation of neamine derived aldehyde, f-butyl isocyanide or isocyanoacetic acid methyl ester, CBZ-N amino acids (xl3) and a glycine conjugated polyethylene glycol methyl ether. The products of the reaction were isolated by precipitation. 

As early as 1961, Ugi [55] theorized the use of multicomponent reactions for the generation of large collections of compounds and, in the following years, other related works were reported [56-58]. It was only recently, though, that the full potential of multiple component condensations (MCCs) for the generation of combinatorial libraries became apparent, due to the efforts of major pharmaceutical industries and academic research groups. 

Tempest PA (2005) Recent advances in heterocycle generation using the efficient Ugi multiple-component condensation reaction. Curr Opin Dmg Discov Devel 8 776-788... 

Polymerization is basically the bonding of two or more monomers to produce polymers/plastics (Chapter 1). A chemical reaction, addition or condensation, in which the molecules of a monomer are linked together to form large molecules whose molecular weight is a multiple of that of the original substance result in high molecular weight components. 

More significant results are the multi-component condensation by way of Michael-aldol and Michael-Michael-aldol reaction sequences and the Michael-Baylis-Hillman tandem, each leading to cyclohexenes bearing multiple functional groups and stereogenic centers. 

Round-bottom or pear-shaped reaction flasks are preferred, but note that stirring with the usual type of magnetic flea is not possible in pear-shaped flasks. The flasks can have multiple necks so that the apparatus can be configured for temperature measurement, addition of solids or liquids, mechanical stirring and inert atmosphere work (p. 125). No matter which arrangement of components is used, always clamp the reaction flask at the neck and keep the heaviest components (such as an addition funnel containing another chemical) vertically above the flask. A condenser will still function at 30° from vertical and it is not very heavy. 

General experimental details are as follows.697b It is usual first to mix the carbonyl component with the amine, which is presented as, e.g., hydrochloride or acetate. An appropriate hydrogen ion concentration must be maintained. For the preparation of aminoalkyl compounds that are liable to hydrolysis it is recommended that the water produced be removed by a drying agent or by azeotropic distillation. Dioxan is a suitable solvent, but it is often recommended that acetic acid be added to it. Ketones react better in alcohol with paraformaldehyde. Copper chloride or iron chloride is said to be a useful addition in reactions of acetylenes. Reactions of amines, phenols, and furans, even under mild conditions, may be accompanied by multiple condensation or resinification. 4-Hydroxybenzylamine is reported706 to be obtained in 92% yield when ammonia is led into a mixture of phenol and formaldehyde. 

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