Oxidative coupling of amines and carbon monoxide catalyzed by palladium complexes. Mono- and double carbonylation reactions promoted by iodine compounds

Abstract

ILAN PRI-BAR and HOWARD ALPER. Can. J. Chem. 68, 1544 ( I 990). Iodine is an effective promoter for the carbonylation of primary and secondary amines to ureas using palladium acetate as the catalyst and a base (e.g. K2CO3) in acetonitrile (3 h at 95OC and 2.7 atm). Oxamides are formed in excellent yields when secondary amines are carbonylated in the presence of iodide ion and oxygen, while primary amines give ureas as the principal product at 95"C, and oxamide at room temperature.

Palladium‐mediated oxidative carbonylation reactions for the synthesis of 11C‐radiolabelled ureas

“…No [ 11 C]urea formation was observed when using secondary amines (reactions 8–10). This observation is in agreement with previous studies of palladium(II)‐catalysed oxidative carbonylation using non‐radiolabelled CO, although palladium(II)‐catalysed formation of N , N , N , N ‐tetrasubstituted ureas from secondary amines has been reported to occur in the presence of an iodine co‐oxidant …”

Transition Metal‐Catalyzed Oxidative Carbonylation of Amines to Ureas

“…Two possible mechanisms for the conversion of primary amines to ureas by palladium‐catalyzed carbonylation were discussed in conjunction with this study. In the first, the critical step is reductive elimination of carbamoyl and amido ligands to generate the urea, as previously proposed by Alper 44. The crucial step in the second possible route involves formation of an intermediate alkyl isocyanate from N ‐monoalkylcarbamoylpalladium species 3 (Scheme ).…”

“…Carbonylation of amines using Pd catalysts has been extensively studied since Tsuji reported the first Pd‐catalyzed carbonylation of amines in 1966 34. Methods for oxidative carbonylation using PdCl 2 as catalyst with copper oxidants or O 2 as the terminal oxidant and CuX or CuX 2 as a mediator have been developed for preparation of ureas,53–55 carbamates,25,56 and oxamides 25,44,57,58. Since a recent review of Pd‐catalyzed reactions is available,12 this Microreview will highlight a few selected examples.…”

Carbonylation of functionalized diamine diols to cyclic ureas: application to derivatives of DMP 450

“…The product was identified by comparison with literature data. 59 3S,4S,5R)-3,4-bis((2-(trimethylsilyl)ethoxy)methoxy)hexane-2,5-diyl)bis(methylcarbamate) (15). Sodium hydride (0.472 g, 0.0197 mmol, 60% dispersion in mineral oil) was washed with dry hexanes.…”