Amides Reactivity Chart

Some amides and hydrazides that have been prepared to protect carboxyl groups are included in Reactivity Chart 6. 

Reactivity Chart 9. Protection for the Amino Group Amides... 

Two new sections on the protection for indoles, imidazoles, and pyrroles, and protection for the amide — NH are included. They are separated from the regular amines because their chemical properties are sufficienth different to affect the chemistry of protection and deprotection. The Reactivity Charts in Chapter 8 are identical to those in the first edition. The chart number appears beside the name of each protective group when it is first discussed. 

Amines, protection of, 309-405 as amides, 348-362 Reactivity Chart 9, 445-449 as carbamates, 315-348 Reactivity Chart 8, 441-444 as special derivatives, 362-385 Reactivity Chart 10, 449-452 Amino acetal derivatives, to protect amines, 392-394... 

Carboxylic acids, protection of, 224-276 as amides and hydrazides, 270-276 as esters, 227-270 Reactivity Chart 6, 433-436 S-Carboxymethyl thioethers, to protect thiophenols, 294-295 Catechols, protection of, 170-174 as cyclic acetals and ketals, 170-172 as cyclic esters, 173-174 Reactivity Chart 4, 425-428 CBZ, see Benzyl carbamates Chloroacetamides, to protect amines, 352-353... 

Acid chlorides are often used in these syntheses because they are the most electrophilic of all acid derivatives and because they can be made from the acids themselves with PCI5 or SOCI2. The other important acid derivatives can all be made from acid chlorides or from any compound above them in the chart of reactivity. So you can make amides from acid chlorides, anhydrides or esters but it is very difficult to make any other derivatives from amides. All derivatives except amides can easily be made from the acids themselves. 

Since amides are the least reactive of the carboxylic acid derivatives (shown on the chart above), we can therefore make amides from any carboxylic acid derivatives that are higher on the chart. In other words, we can make amides from acid halides, from anhydrides, or from esters. 

Answer We must convert an amide into an ester, but we have not learned a way to do this directly in one step (because that would involve going up the chart). Amides are less reactive than esters, so we cannot go directly from an amide to an ester. Instead, we can first convert the amide into a carboxylic acid, and then we can convert the carboxylic acid into an ester ... 

On the basis of the reactions presented in this chapter, write reaction summary charts for esters and amides similar to the chart for acyl halides (Figure 20-1). Compare the number of reactions for each of the compound classes. Is this information consistent with your understanding of the relative reactivity of each of the functional groups ... 

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