CDT | 1,1'-Carbonyldi(1,2,4-triazole) | CAS 41864-22-6 | ≥95%

CDT (1,1'-carbonyl-di-(1,2,4-triazole); di(1H-1,2,4-triazol-1-yl)methanone) is a crystalline carbonyl-transfer and condensing reagent in the same azole-carbonyl family as CDI. It reacts with carboxylic acids to give acyl triazolide intermediates in which the 1,2,4-triazole ring acts as the leaving group. Because 1,2,4-triazole is substantially more acidic as an N–H azole than imidazole, the corresponding triazolate is a weaker base and better leaving group than imidazolate. Acyl triazolides are therefore more electrophilic acyl donors than the corresponding acyl imidazolides, which can improve acyl-transfer efficiency with hindered alcohols, weakly nucleophilic amines, or substrates that respond poorly to imidazolide activation. CDT provides non-phosgene carbonyl-transfer chemistry for selected acylation and carbonylation workflows.

Activation of carboxylic acids as acyl triazolides

CDT converts carboxylic acids into reactive acyl triazolides, activated acyl-transfer species in which 1,2,4-triazole serves as the leaving group. This higher reactivity makes CDT useful where carbodiimide or imidazolide activation gives incomplete conversion or demands forcing conditions, including acylation of sterically hindered alcohols and weakly nucleophilic aromatic amines. The activated intermediate reacts with amine nucleophiles to give amides, with the higher electrophilicity of the acyl triazolide useful when imidazolide activation is insufficient.

Thioester and selenoester formation

Acyl triazolides generated from CDT undergo thiolysis or selenolysis to give thioesters and selenoesters. These products are useful acyl-transfer intermediates and softer electrophiles than ordinary oxoesters, and CDT provides access to them from the parent carboxylic acid without isolating an acid chloride.

Phosgene substitute for ureas and carbamates

CDT is used as a non-phosgene carbonyl-transfer reagent for urea and carbamate synthesis. Sequential displacement of the two triazole leaving groups allows stepwise carbonyl transfer to nitrogen and oxygen nucleophiles, making CDT useful where a solid azole-carbonyl reagent is preferred over phosgene-type reagents.

Esterification of unprotected glucose

CDT-derived acyl triazolides have been used for direct esterification of unprotected glucose to give β-D-glucosyl esters. This is a useful carbohydrate-acylation example because it avoids a protecting-group sequence and exploits the reactivity balance of the acyl triazolide toward the unprotected sugar substrate.

Singlet-oxygen generation for oxidation chemistry

CDT reacts with hydrogen peroxide as a dehydrating/activating reagent to generate singlet molecular oxygen. This CDT/H₂O₂ system has been used in oxidation chemistry, including epoxidation, where singlet oxygen is generated in situ under mild conditions.