1.3- Dicyclohexylcarbodiimide amide formation

Mechanism of amide formation using dicyclohexylcarbodiimide. Test yourself on the concepts in this figure at OrganicChemistryNow. 

Amide Formation Using Dicyclohexylcarbodiimide Section 26.7 Figure 26.4... 

Amide formation from the carboxylic acid is much easier if the acid is first activated. Several activating agents have been developed that greatly facilitate amide formation. Dicyclohexylcarbodiimide (DCC) is used most often (Fig. 17.36). 

Mechanism of amide formation by reaction of a carboxylic acid and an amine with dicyclohexylcarbodiimide (DCC). 

Thus unsubstituted (R=H) and substituted (R = alkyl) non-stabilized diyiides 1 react with phenylisocyanate and dicyclohexylcarbodiimide (R NCX), leading to the formation of new monoylide type intermediates. These last ones react in situ with carbonyl compounds through a Wittig type reaction leading respectively to a,)8-unsaturated amides 2 and amidines 3, with a high E stereoselectivity, the double bond being di- or tri-substituted [48,49]. By a similar reactional pathway, diyiides also react with carbonic acid derivatives, with the synthesis as final products of -a,/l-unsaturated esters 4 and acids 5 [50]. 

Coupling of the two amino acids is achieved by A. A -dicyclohexylcarbodiimide (DCCl)-promoted amide bond formation between the free amino group of leucine benzyl ester and the free carboxyl group of Z-protected alanine. 

The most frequently used approaches for derivatizing carboxylic acids are esterification with a variety of single-enantiomer alcohols, or formation of amides with single-enantiomer amines [234,252]. The formation of amide derivatives requires activation of the carboxylic acid by formation of the acid chloride with thionyl chloride, mixed anhydrides with chloroformates, N-acylimidazoles with 1,1 -carbonyldiimidazole or N-acylureas with dicyclohexylcarbodiimide. Esterification reactions generally re-... 

Amide Bond Formation Between a Carboxylic Acid and an Amine Using N,N -Dicyclohexylcarbodiimide 1152 Carboxypeptidase-Catalyzed Hydrolysis 1162... 

Formation of diastereomeric amides using N,N-dicyclohexylcarbodiimide as a coupling agent... 

---