181306-52-5Relevant articles and documents
HIGH-VALENT PALLADIUM FLUORIDE COMPLEXES AND USES THEREOF
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Page/Page column 77-78, (2012/03/11)
The present invention provides novel high-valent palladium complexes. The complexes typically include multi-dentate ligands that stabilize the octahedral coordination sphere of the palladium(IV) atom. These complexes are useful in fluorinating organic compounds and preparing high-valent palladium fluoride complexes. The invention is particularly useful for fluorinating compounds with 19F for PET imaging.
Catalytic asymmetric heterogeneous aziridination of styrene using CuHY: Effect of nitrene donor on enantioselectivity
Taylor, Sophia,Gullick, John,McMorn, Paul,Bethell, Donald,Page, Philip C. Bulman,Hancock, Frederick E.,King, Frank,Hutchings, Graham J.
, p. 1714 - 1723 (2007/10/03)
The copper-catalysed aziridination of styrene with copper-exchanged zeolite Y (CuHY) and copper(II) triflate (trifluoromethanesulfonate) (Cu(OTf)2) as catalysts is described in detail. Two nitrene donors, [N-(p-tolylsulfonyl)imino)]phenyliodinane (PhI=NTs) and [N-(p-nitrophenylsulfonyl)imino]phenyliodinane (PhI=NNs) are compared. Modification of the catalyst with bis(oxazolines) affords enantioselective catalysts and a range of chiral bis-(oxazolines) has been studied. The ratio of nitrene donor to styrene is shown to be an important factor controlling both the yield and ee of aziridine formed. The best results are obtained with PhI=NNs; ee, ≥ 90%, together with high yields (≥ 85%), can readily be achieved with this nitrene donor using acetonitrile as solvent. Addition of the nitrene donor over a period of time, rather than all at the start of the reaction, is shown to enhance the yield of the aziridine but the ee is significantly decreased for both the homogeneous and the heterogeneous catalysts. Experiments in which the breakdown products of the nitrene donor, iodobenzene and the corresponding sulfonamide, are added at the star of the reaction show that a complex interplay exists at the copper active site between the reactants, products, chiral modifier and the solvent. However, the heterogeneous catalyst, CuHY, is found to give enhanced enantioselection for a range of bis(oxazolines) compared to the homogeneous catalyst, and the effect is considered to be due to the confinement of the catalyst within the micropores of the zeolite.
The rhodium(II)-catalyzed aziridination of olefins with {[(4- nitrophenyl)sulfonyl]imino}phenyl-λ3-iodane
Müller, Paul,Baud, Corine,Jacquier, Yvan
, p. 738 - 750 (2007/10/03)
The aziridination of olefins with {(4- nitrophenylsulfonyl)imino}phenyl-λ3-iodane, NsN=IPh (1c), in the presence of [Rh2(OAc)4] proceeds in yields of up to 85% when the olefin is used in large excess. Under optimized conditions, styrene (4a) is aziridinated with 1 equiv. of NsN=IPh (1c) in 64% yield with 2 mol% of catalyst. The aziridines derived from electron-rich olefins undergo ring-opening under the conditions of the aziridination and afford rearrangement products or pyrrolidines. The aziridination is sterospecific with 1,2-dialkyl- and 1,2-arylalkyl- disubstituted olefins, but nonstereospecific with stilbene. The ρ-value for aziridination of substituted styrenes iS -0.61. No ring-opened products are observed upon aziridination of vinylcyclopropanes. In the presence of chiral Rh(II) catalysts, the aziridination is enantioselective, affording an ee of 73% with cis-β-methylstyrene (4k) and Pirrungs [Rh2{(R)-(-)-bnp}4] catalyst. The experimental results are consistent with a one-step mechanism for transfer of the nitrenoid moiety from the catalyst to the olefin.
Preparation and evaluation of nitrene precursors (PhI=NSO2Ar) for the copper-catalyzed aziridination of olefins
Soedergren, Mikael J.,Alonso, Diego A.,Bedekar, Ashutosh V.,Andersson, Pher G.
, p. 6897 - 6900 (2007/10/03)
The preparation of different [N-(arenesulfonyl)imino]phenyliodinanes is described along with an evaluation of their utility as nitrene precursors for the copper-catalyzed aziridination of different olefins. The best results were obtained with p-NO2/
