Amination acylamination

Preparation of Isocyanates. Isocyanates are prepared by rearrang-ii azides in inert solvents such as ethers, chloroform, benzene and its homologs, malonic ester, mid ligroin. If the isocyanate is to be isolated, the solvent is removed by distillation, or, if the isocyanate is the lower boiling, it is distilled directly. In this operation, a safety shield is advisable to guard against a possible explosion of yet undecomposed azide. Isocyanates can be converted to sym-ureas by reaction with water, to urethans by reaction with alcohols, to os-ureas by reaction with amines, or to acylamines by reaction with anhydrous acids or acid anhydrides, or they can be hydrolyzed directly to amines. Acylamines can also be obtained. from isocyanates by reaction with Grignard re-... 

Smooth acylaminations are also given by isocyanate adducts of 3-phenyloxaziridine. Ammonia and primary as well as secondary amines form the corresponding semicarbazides, e.g. (102). Owing to the fast amination reaction, shortlived substances like triazanes become accessible, e.g. the cyclohexyl compound (103), which is stable for only a few minutes at room temperature. 

The next step in the development of periodate oxidation was made by Nicolet and Shinn.8 They applied periodate oxidation to a series of a-amino acids, and found that those containing the 2-hydroxyamine structure are almost instantaneously oxidized. For such an oxidation to proceed rapidly, the amine could not be tertiary. An a-hydroxy A-acylamine was attacked very slowly, if at all. Only a small number of compounds were investigated. 

In cases of some derivatives bearing an amino substituent, conversions to acylamines, alkylamines, and amidines have been reported. These substrate amines include the above-mentioned two amino compounds 157 and 159 as well as other compounds shown in Scheme 25. 

In studying the reactions betw nitroso-acylamines and diazo esters several expl compds were prepd. Some reactions involved explosion hazards) 4) F. Bucci, AnnChim (Rome), 41, 587-93(1951) CA 47, 3443 (1953) (Reactions of alkali nitrites with some otg amines, such as urea may result in explns) 5) G. Armistead, ChemEngt-Progress 48, 5-10(1952) CA 46, 2298 (1952) (A review of expln hazards)... 

Meth-Cohn and Suschitzky41 examined this reaction further and observed that the acylamines (131) reacted as easily and more cleanly than the parent amines, especially with performic acid (see... 

A rather different cyclization process occurs when (65) is treated with tri-flooroperacctic [172] or other peracids (Scheme 2.1.26) [173]. The acylamines appear to react most cleanly, with performic acid giving yields of (68) in the range 43-91% for a wide range of compounds. The o-substituted anilides (65) are made by treatment of o-chloronitrobenzene (1 mol) with the appropriate amine (2.1 mol) followed by reduction, and acylation with formic acid, acetic anhydride or benzoyl chloride [173]. 

The next part is devoted to the D-fructosylamines the substituted amino function includes acyl- as well as aryl-amines, and even amino acids. At the time of the previous review,principally acylamines had been synthesized, but the mechanism of formation has since been elucidated, and it thus became possible, by adjusting the reaction medium, to obtain higher yields and crystalline derivatives. 

The book is divided into chapters according to the identities of X and Y, the arrangement being alphabetical as far as possible. For example, reactants in which X and Y are amine and carboxamide, respectively, are considered in Chapter 46 while those where X and Y are hydroxy and methylene are contained in Chapter 99. Where only a few examples of a particular X and Y combination were found in the literature, these are included with cyclizations of closely related groups for example. Chapter 20 contains ring closures of substrates having either acylamine or amine and thiocyanate. 

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