Amides from isocyanates

Subst. carboxylic acid amides from isocyanates Phenanthridones o... 

N-Subst. carboxylic acid amides from isocyanates Carboxylic acid amides from acylisocyanates via N-acylcarboxylic acid amides... 

Several name reactions are promoted by AICI3. For example, the Darzens-Nenitzescu reaction is simply the acylation of alkenes. The Ferrario reaction generates phenoxathiins from diphenyl ethers (eq 19) The rearrangement of acyloxy aromatic systems is known as the Fries rearrangement (eq 20). Aryl aldehydes are produced by the Gatterman aldehyde synthesis (eq 21). The initial step of the Haworth phenanthrene synthesis makes use of a Friedel-Crafts acylation. The acylation of phenolic cort tounds is called the Houben-Hoesch reaction (eq 22). The Leuckart amide s)oithesis generates aryl amides from isocyanates (eq 23). ... 

Isocyanates react with carboxylic acids to form amides, ureas, anhydrides, and carbon dioxide, depending on reaction conditions and the structure of the starting materials (Scheme 4.13). Aliphatic isocyanates more readily give amides. Aromatic isocyanates tend to react with carboxylic acids to first generate anhydrides and ureas, which at elevated temperatures (ca. 160°C) may further react to give amides. In practice, the isocyanate reaction with carboxylic acid is rarely utilized deliberately but can be an unwanted side reaction resulting from residual C02H functionality in polyester polyols. 

Examples of non-urethane linkages derived from isocyanates a) urea, b) urea, c) biuret, d) amide, and e) allophanate... 

The dominance of an alkoxy group over a silyl group is manifested in the generation of amides from reaction of oc-silyl enol ethers with chlorosulfonyl isocyanate, followed by hydrolysis. Simple vinylsilanes and alkynylsilanes undergo carbamidation [34],... 

There are several types of chiral derivatizing reagents commonly used depending on the functional group involved. For amines, the formation of an amide from reaction with an acyl halide [147,148], chloroformate reaction to form a carbamate [149], and reaction with isocyanate to form the corresponding urea are common reactions [150]. Carboxyl groups can be effectively esterified with chiral alcohols [151-153]. Isocynates have been used as reagents for enantiomer separation of amino acids, iV-methylamino acids, and 3-hydroxy acids [154]. In addition to the above-mentioned reactions, many others have been used in the formation of derivatives for use on a variety of packed and capillary columns. For a more comprehensive list, refer to References 155-159. 

However, it follows from the processes discussed so far that in some reactions growth centres are also regenerated. For example, decomposition of the anion of a substituted keto amide yields lactam anions as well as isocyanate which is an effective activator, reaction (35). Acyl-lactam growth centres are also generated from keto amide and isocyanate, scheme (45). At high temperatures, lactam anions are generated also from carbonate [130,145,146]... 

We have recently been examining chemistry that allows the preparation of RIM derived polyamides from isocyanates. We reported sane initial results during a previous RIM symposium held in Atlanta. (2-3) We reported the use of enamine isocyanate chemistry to give amide products (equation 1). 

A-Phosphorylated imidazoles and benzimidazoles can be made by direct phosphorylation by halides, esters, amides, amidoesters, isocyanates, and thiocyanates of phosphorus-containing acids, or from reaction of phosphonic or phosphinic imidazolides with a sulfonic acid or anhydride <82CB1636>. Stable charge transfer complexes are produced when a 1 1 or 1 2 ratio of imidazole (or benzimidazole) and sulfur trioxide are refluxed in ether, dioxane, THE, or 1,2-dichloroethane. These complexes are stable on storage in the absence of water and have sharp melting points. Indeed, the benzimidazole SO3 complex must be boiled for five hours in water to decompose it. On fusion, the complexes form the C-sulfonic acids (see Section 3.02.5.3.3) <87CHE1084>. Sulfonyl chlorides readily A-sulfonate imidazoles <94JMC332>. 

Preparation of acylureas from amides and isocyanic esters requires more critical conditions but generally gives good yields. 

A urethane (also called a carbamate) is a functional group that is simultaneously an ester and an amide at a single carbonyl group. Urethanes are commonly prepared from isocyanates and alcohols. 

With isocyanates (Eq. 72) a Barbier reaction leading to aromatic amides from an aryl bromide is best done with sodium. ... 

For a relevant review see Vaultier, M. Lorvelec, G. Plunian, B. Paulus, O. Bouju, P. Mortier, J. Recent Developments in the Use of a,)3-Unsaturated Boronates as Partners in Diels-Alder Cycloadditions Royal Society of Chemistry Special Publication 253 (Contemporary Boron Chemistry, 2000, 464-471. For another relevant article see LeBel, N. A. Cherluck, R M. Curtix, E. A. Improved synthesis of amides from the Curtius reaction. Reaction of isocyanates and organolighium compounds Synthesis 1973, 678-679. 

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