Acid anhydride, amides from naming

Acid anhydride, amides from, 807 eleclrostatic potential map of, 791 esters from, 807 from acid chlorides, 806 from carboxylic acids, 795 1R spectroscopy of, 822-823 naming, 786... 

Carboxylic acids and their derivatives like esters, amides, anhydrides, and acyl halides are formally synthesized from olefins, carbon monoxide, and compounds represented by Nu-H such as H2O, ROH, RNH2, RCOOH (Equations (4) and (5)). Alkynes also react under similar conditions to afford the corresponding unsaturated carboxylic acid derivatives. These reactions have been named hydrocarboxylation, hydroalkoxycarbonylation, and hydroaminocarbonylation. 

Trypsin was named more than 100 years ago. It and chymotrypsin were among the first enzymes to be crystallized, have their amino acid sequences determined, and have their three-dimensional structure outlined by x-ray diffraction. Furthermore, both enzymes hydrolyze not only proteins and peptides but a variety of synthetic esters, amides, and anhydrides whose hydrolysis rates can be measured conveniently, precisely and, in some instances, extremely rapidly. As a result, few enzymes have received more attention from those concerned with enzyme kinetics and reaction mechanisms. The techniques developed by the pioneers in these various fields have enabled other serine proteases to be characterized rapidly, and the literature on this group of enzymes has become immense. It might be concluded that knowledge of serine proteases is approaching completeness and that little remains but to fill in minor details. 

As can be seen from equations 2-5, the formation of A -acylenamines proceeds from derivatives of carboxylic acids (having an oxidation level equal to three ), namely anhydrides or add halides RCOX or amides RCONH2, on the one hand, and from carbonyl compounds or their derivatives (oxidation level equal to two ), namely enamines 3, acetylenes 5, or vinyl ethers 6, on the other. Indeed, the acetylenes 5, being the dehydration products of enols, may be regarded as having a masked carbonyl functionwhile the enamines 3 rank with vinyl ethers, vinyl esters and enols, as the heteroanalogs of these carbonyl derivatives (see Section IV). 

Notably, not only the 2,4-dimethoxycinnamates underwent the BF3-Et20 mediated tetramerization reaction, and this has proved the versatility of the reaction. In fact, also 2,4-dimethoxycinnamic acid amides such as 12 (Scheme 8.5), derived from the mixed anhydride of 2,4-dimethoxycinnamic acid with 1- or d-vaUne ethyl ester, upon treatment with BF3-Et20 yielded the amido-resorc[4]arenes 13a-C which proved to be chiral for the presence of four axial pendants containing the chiral valine residue [9]. A novel flattened-partial cone conformation was isolated for the first time from the reaction mixture, together with three other stereoisomers (namely, 1,2-altemate, flattened-cone, and chair). The flattened-cone stereoisomer, which was identified by molecular modeling as the most stable, proved to form as minor product in kinetic conditions, and to become the main component of the reaction mixture under more drastic conditions (namely, substrate/ BF3 Et20 = 1 400 M ratio). The chiral amido-resorc[4]arenes 13a-c were obtained in enantiomerically pure forms, as checked by enantioselective HPLC. 

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