Reactions of Carbodiimides. I. The Mechanisms of the Reactions of Acetic Acid with Dicyclohexylcarbodiimide^1,2

Abstract

Hanovia Type S 200-w lamp through a Pyrex filter until ultraviolet or vpc analysis of the irradiated solution showed maximum product formation (about 5 hr). The retention time of the photo product on a 10-ft vpc column was 6.3 min and for the dienone, 7.8 min. After solvent removal the crude oil obtained was distilled, bp 60°( 0.5 mm), to give 1.5 g (50%) of a crystalline product 18 which on further purification by vpc or sublimation had mp 50-52°; **"° 235, 274, and 320 µ (shoulder) (e 6270, 3240, and 605, respectively); 1690 and 1640 cm-1.

Reaction of RF-palmitic acid-F13 with dicyclohexylcarbodiimide

“…The IR spectrum of the adduct shows strong absorptions at 1658 and 1698 cm À1 which are essentially identical to the values reported for the product of DCC with acetic acid [5] in which rearrangement to the acetyldicyclohexylurea has occurred. These findings support the argument that the isolated product is in fact the rearranged product 3, which is now confirmed by X-ray crystallography.…”

“…The bulky DCC group can be effectively employed to function as an end cap for a variety of rotaxanes [2] and the reagent is particularly useful for the acylation step in the synthesis of polypeptides from amino acids [3,4]. The acyl group is highly reactive in this environment because cleavage of the acyl-oxygen bond converts the C N bond of the isourea to a more stable C O moiety [5][6][7]. Although this O-acyl to N-acyl migration has been reported several times [5][6][7][8][9] little detailed structural information on the products has been available due to the paucity of X-ray crystallographic data.…”

“…The acyl group is highly reactive in this environment because cleavage of the acyl-oxygen bond converts the C N bond of the isourea to a more stable C O moiety [5][6][7]. Although this O-acyl to N-acyl migration has been reported several times [5][6][7][8][9] little detailed structural information on the products has been available due to the paucity of X-ray crystallographic data. Interpretation of 13 C NMR data for these compounds is not straightforward, due to the possibility of geometrical isomers about the C N in the isoureas [8] and restricted rotation about amide type bonds in the ureas.…”

Chemical amplification with encapsulated reagents

“…Nonetheless, the reaction proceeds slowly through whatever concentration of DCC is available in solution. The products are DCU 6, the anilide 4a and a side product (13,14) N-acylurea (not shown). The capsule gradually fills with DCU and anilide.…”

Quantum Dots Protected with Tiopronin: A New Fluorescence System for Cell‐Biology Studies

“…We used this reactivity for the functionalization of the quantum dots with a Tat proteinderived peptide sequence. The reactions utilize the water-soluble carbodiimide N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide hydrochloride (EDC) [17] to catalyze reactions between CdS@tiopronin acid groups and Tat protein-derived peptide sequence amine groups. We included N-hydroxysulfosuccinimide in the reaction mixture to improve the efficiency of the carbodiimide-mediated amide-forming reaction by producing hydrolysis-resistant active ester reaction intermediates (Scheme 2).…”