Oxidative Diamination of Alkenes with Ureas as Nitrogen Sources: Mechanistic Pathways in the Presence of a High Oxidation State Palladium Catalyst
作者:Kilian Muñiz、Claas H. Hövelmann、Jan Streuff
DOI:10.1021/ja075041a
日期:2008.1.1
identical mechanism where stereochemistry is concerned. It exemplifies the importance of cationic palladium(IV) intermediates prior to the final reductiveeliminationfrom palladium and proves that the nucelophile for this step stems from the immediate coordination sphere of the palladium(IV) precursor. These results have important implications for the general development of alkene 1,2-difunctionalization
Metal-Free Oxidative Cyclization of Urea-Tethered Alkenes with Hypervalent Iodine
作者:Brian M. Cochran、Forrest E. Michael
DOI:10.1021/ol8022165
日期:2008.11.6
A metal-free oxidative cyclization of ureas onto unactivated alkenes using iodosylbenzene and an acid promoter is described. The products isolated are predominantly bicyclic isoureas resulting from an intramolecular oxyamination reaction. The acid type and urea substitution have a strong effect on the product formed. A variety of substrates form the isourea with high diastereoselectivity via syn addition
Oxidative Interception of the Hydroamination Pathway: A Gold-Catalyzed Diamination of Alkenes
作者:Alvaro Iglesias、Kilian Muñiz
DOI:10.1002/chem.200901199
日期:2009.10.12
complimentary diamination of alkenes by using homogeneous gold catalysts is described. The reaction is one of very few examples of homogeneous goldoxidation catalysis and proceeds with high selectivity under mild conditions. Individual steps of the suggested catalytic cycle were investigated on isolated model gold complexes, and new pathways for gold‐catalyzed amination reactions were established. The key step
An enantioselective synthesis of tetrhydropyrrolo[1,2-c]pyrimidine-1,3-diones via a palladium-catalyzed intramolecular oxidative aminocarbonylation is described. The carbon-carbon double bond of alkenylurea substrates has been shown to react intramolecularly with a nitrogen nucleophile in the presence of a palladium catalyst under a carbon monoxide atmosphere. The use of a chiral Spiro bis(isoxazoline) ligand (SPRIX) is essential to obtain the desired products in optically active forms. In comparison with the coordination ability of other known ligands, this peculiar character of SPRIX originates from two structural characteristics: low sigma-donor ability of the isoxazoline coordination site and rigidity of the spiro skeleton.
Intramolecular diamination and alkoxyamination of alkenes with N-sulfonyl ureas employing N-iodosuccinimide
作者:Hao Li、Ross A. Widenhoefer
DOI:10.1016/j.tet.2010.03.082
日期:2010.6
Reaction of N-delta-alkenyl-N'-sulfonyl urea 1 with N-iodosuccinimde (NIS; 2 equiv) and a catalytic amount of AgOTf (20 mol %) at room temperature led to intramolecular alkoxyamination to form bicyclic isourea 2a in 95% isolated yield. In comparison, reaction of 1 with NIS and sodium bicarbonate (1 equiv) at room temperature led to isolation of bicyclic imidazolidin-2-one 2b in 91% yield. These NIS-mediated alkoxyamination and diamination protocols were effective for a range of N-delta-alkenyl-N'-sulfonyl ureas to form the corresponding heterobicyclic compounds in good yield with high chemoselectivity and good to excellent diastereoselectivity. (C) 2010 Published by Elsevier Ltd.