Acetamide synthesis acetic anhydride

Anhydrides react readily with diverse nucleophiles such as amines. For example, the use of acetic anhydride was reported in the 1850s to produce acetamides (40). Symmetric anhydrides 16 can be prepared by dehydrating the corresponding acid under strong acidic conditions or at high temperatures. A more practical approach, however, consists of treating the carboxylic acid with DCC 17 (41). The anhydride is then subjected to aminolysis with the desired amine (see Fig. 5). This method is nsually applicable to peptide synthesis, and, in theory, no additional base is required, as the carboxylate anion is produced in situ. Unfortunately, half of the acid is wasted during the... 

The synthesis of 3-benzoyl-A-homo-3-aza-5) -androstan-16-one (37), an analogue of the alkaloid samanine (36) from Salamandra maculosa, has been reported. Sodium borohydride reduction of the known compound (38) followed by tosylation alTorded the tosylate (39) the nitrile group was reduced by diborane and cyclized by benzoic anhydride-pyridine to the derivative (40a) similar cyclization with acetic anhydride-pyridine yielded the related acetamide (40b). This cyclization requires one equivalent of anhydride and the uncyclized amide is not an intermediate in the reaction. Jones oxidation of (40a) was followed by conversion into a benzylidene ketone derivative (41) with benzaldehyde-KOH in methanol. Reduction of (41) with sodium borohydride and acetylation furnished (42). Treatment of compound (42) with ozone followed by mild zinc reduction produced an acetoxy-ketone, which was further reduced by Zn-HBr-CH2Cl2 to the ketone (37). 

The synthesis of a water-soluble diphenylmethano-bridged fullerene 122 was achieved by hydrolyzing the bis (acetamide) 121 with acetic acid-aqueous hydrochloric acid and then converting it into the bis(succinamide) 122 by treatment with succinic anhydride (Scheme 4.25) [158]. Compound 122 is soluble in water at pH > 7. This is an important requirement for the investigation of the biological activity of fullerenes. Remarkably, 122 is an inhibitor for the HIV enzymes protease (HIV-P) and reverse transcriptase (HIV-RT) [159]. As suggested by molecular modeling. 

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