Urea as the Most Reactive and Versatile Nitrogen Nucleophile for the Palladium(2+)-Catalized cyclization of Unsaturated Amines

Article abstract of DOI:10.1021/ja00220a044

Urea (known as an ambident nucleophile) serves as a specific nitrogen nucleophile for the palladium(2+)-catalized aminocarbonylation of unsaturated amines.N-2-propenyl-, N-3-butenyl-, N-4-pentenyl, and N-5-hexenylureas undergo an aminocarbonylation (0.1-0.01 equiv of PdCl2, 3.0 equiv of CuCl2, 1 atm of CO in methanol at 0 deg C to room temperature) to provide 4-<(methoxicarbonyl)methyl>-2-imidazolidinones, 4-<(methoxycarbonyl)methyl>-3,4,5,6-tetrahydro-2(1H)-pyrimidinones, 1,3-diazabicyclo<4.3.0>nonane-2,4-diones, and 1,3-diazabicyclo<4.4.0>decane-2,4-diones, respectively, in high yields.The effects of solvents and the R¹ and R² substituents of N-2-propenylureas 1(2-propenyl)NCONHR²> and N-3-butenylureas 1(3-butenyl)NCONHR²> on the ease of cyclization and the relative reactivity of amino nucleophiles (urea>carbamate>tosylamide>benzamide) toward the cyclization are also discussed.