Naming, acid anhydrides amines

Nadicimide end-capped oligomers were usually prepared in two steps namely preparation of amine terminated nadicimide and chain extension with a dianhydride. Appropriate quantities of nadic or methyl nadic anhydride and diamine in glacial acetic acid were refluxed for several hours and the amine terminated nadicimide was recovered by precipitation. Then chain extension with 6FDA was carried out in acetone at 60 C. Chemical imidization of the amic acid to imide was carried out using sodium acetate and acetic anhydride [130,131]. Instead of diamines, triamines can also be used [132-134]. Chemical structure of nadicimide end-capped resins prepared from di and triamine (Figure 23) is given below. 

Methods for the A-acylation of similar heterocycles, such as simple thiazolidinethiones, have been reported since 1977, namely acyl chlorides in miscellaneous conditions,586 or carboxylic acids under DCC-activation.60,61 However the easiest and most effective method involves acyl chlorides or carboxylic anhydrides in the presence of an amine.47 Applying that procedure on carbohydrate scaffolds Rollin and co-workers62 reported the synthesis of diverse /V-acylated OZTs. The reactions were performed with good yields and the /V-selective acylation was ascertained by NMR— namely the thiocarbonyl 13C chemical shift (Scheme 41). Thanks to the dual nature of the carbanion drifting in the reaction,596 60 no competitive formation of the thioester, as mentioned by Plusquellec el al. in the case of benzothiazole, was observed. 

The cyclohexene 121, which was readily accessible from the Diels-Alder reaction of methyl hexa-3,5-dienoate and 3,4-methylenedioxy-(3-nitrostyrene (108), served as the starting point for another formal total synthesis of ( )-lycorine (1) (Scheme 11) (113). In the event dissolving metal reduction of 121 with zinc followed by reduction of the intermediate cyclic hydroxamic acid with lithium diethoxyaluminum hydride provided the secondary amine 122. Transformation of 122 to the tetracyclic lactam 123 was achieved by sequential treatment with ethyl chloroformate and Bischler-Napieralski cyclization of the resulting carbamate with phosphorus oxychloride. Since attempts to effect cleanly the direct allylic oxidation of 123 to provide an intermediate suitable for subsequent elaboration to ( )-lycorine (1) were unsuccessful, a stepwise protocol was devised. Namely, addition of phenylselenyl bromide to 123 in acetic acid followed by hydrolysis of the intermediate acetates gave a mixture of two hydroxy se-lenides. Oxidative elimination of phenylselenous acid from the minor product afforded the allylic alcohol 124, whereas the major hydroxy selenide was resistant to oxidation and elimination. When 124 was treated with a small amount of acetic anhydride and sulfuric acid in acetic acid, the main product was the rearranged acetate 67, which had been previously converted to ( )-lycorine (108). 

Olefinic esters may be obtained directly by the Knoevenagel reaction. Alkyl hydrogen malonates are used in place of malonic acid. Decarboxylation then gives the ester directly as in the preparation of ethyl 2-heptenoate (78%) and methyl m-nitrocinnamate (87%). Alkyl hydrogen malonates are readily available by partial hydrolysis of dialkyl malonates. The use of malonic ester in the condensation leads to olefinic diesters, namely, alkylidenemalonates such as ethyl heptylidenemalonate (68%). A small amount of organic acid is added to the amine catalyst since the salts rather than the free amines have been shown to be the catalysts in condensations of this type. Various catalysts have been studied in the preparation of diethyl methylenemalonate. Increased yields are obtained in the presence of copper salts. Trimethylacetalde-hyde and malonic ester are condensed by acetic anhydride and zinc chloride. Acetic anhydride is also used for the condensation of furfural and malonic ester to furfurylidenemalonic ester (82%). ... 

Tilak et described the use of excess mixed carbonic anhydrides to force condensation reactions to completion followed by the destruction of the excess mixed anhydride via the addition of aqueous potassium hydrogencarbonate. Hydrolysis of the nnixed anhydride was rapid and the resulting protected dipeptide could be extracted into ethyl acetate in a high state of purity, leaving the excess amino acid derivative and the salts in the aqueous phase. Without further purification the protected dipeptide was N -deprotected and reacted with the next mixed anhydride, and the process repeated until the desired peptide was obtained. Beyerman et al. substantially expanded the scope of this procedure and named it the REMA method for peptide synthesis (Repetitive Excess Mixed Anhydride).P°1 These reaction conditions provide an excellent method to ensure complete reaction of the amine component as well as rapid reaction rates and minimal side products. However, care must be taken to ensure that the excess carboxylic acid component is soluble in sodium hydrogencarbonate solution, e.g. when Z-Asp(OBzl)-OH is the acid component, it is extracted into the ethyl acetate as the sodium salt along with the product. With the due precautions the yields of small peptides are so high that the method could be applied without purification of the intermediate products, that is, in a repetitive way. 

For bringing about the first reaction the following-named substances may be used as condensation agents hydrochloric acid, acetic anhydride, as well as primary and secondary amines (ethyl amine, diethyl amine, piperidine, and others). For the second reaction the bases mentioned may be used. A small quantity of one of these may produce la rge quantities of the condensation product this is a case of a so-called continuous reaction. It is probable that the amine reacts first with the aldehyde, water being eliminated 1... 

The compound of oxidation state intermediate between that of lupinine and lupininic acid, namely, lupinal, C10H17NO, m.p. 93-96°, has been obtained by Zaboev (72) through the use of chromic anhydride in acetic acid. It appears that the first use of natural lupinine itself as a synthetic tool dates from the work of Bartholomaus and Schaumann, described in two patents (150, 151). Products were characterized which resulted from the condensation of chloro- or bromo-lupinane (derived from lupinine (124, 125)) with ammonia, aniline, methylamine, dimethyl-amine, and piperidine (150). The product resulting from chlorolupinane and piperidine was also described by Clemo and Paper (126). Compounds of possible therapeutic interest were made by the condensation of a halolupinane with 8-amino-2-methylquinoline, 4-amino-2-methyl-quinoline, and by the combination of methylaminolupinane with 4-chloro-... 

Liebermann discovered the reaction between nitrous acid and phenols and secondary amines named after him. He prepared amino-naphthols from nitro-naphthols, synthesised the dihydroxyanthraquinones anthrarufin and chrysazin, and studied the reduction of anthraquinone. Another dihydroxy-anthraquinone, quinizarin, was discovered by F. Grimm by heating hydro-quinone with phthalic anhydride. 

There are a number of ways that a stepwise reaction can take place. These include direct reaction, interchange, and add chloride/anhydride. Direct reactions include formation of polyesters and polyamides. Typical interchange reactions involve acetol-alcohol, amine-amide, and amine-ester. The last-named are cases in which an anhydride or acid chloride are reacted with a glycol or amine. 

In Summary Esters are named as alkyl alkanoates. Many of them have pleasant odors and are present in nature. They are less reactive than acyl halides or carboxylic anhydrides and therefore often require the presence of acid or base to transform. With water, esters hydrolyze to the corresponding carboxylic acids or carboxylates with alcohols, they undergo transesteriflcation and, with amines at elevated temperatures, furnish amides. 

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