158657-40-0Relevant academic research and scientific papers
Stereoselective Construction of γ-Lactams via Copper-Catalyzed Borylacylation
Bajohr, Jonathan,Lautens, Mark,Polishchuk, Iuliia,Torelli, Alexa,Whyte, Andrew
, p. 7915 - 7919 (2020/11/02)
A versatile and highly stereoselective borylative cyclization to generate polyfunctionalized γ-lactams has been developed. The stereoselective synthesis of these key ring systems is crucial due to their ubiquity in natural products. We report the diastero- and enantioselective construction of di- and trisubstituted γ-lactam cores, with examples containing an enantioenriched quaternary carbon.
Switching the N-Alkylation of Arylamines with Benzyl Alcohols to Imine Formation Enables the One-Pot Synthesis of Enantioenriched α-N-Alkylaminophosphonates
Hofmann, Natalie,Hultzsch, Kai C.
supporting information, p. 3105 - 3111 (2019/06/08)
The selective N-alkylation of anilines with benzylic alcohols can be switched in favor of the dehydrogenative condensation process using the nitrile-ligated Kn?lker's complex by conducting the reaction either in a closed system under inert conditions, or in an open system in air. The selective formation of imines, containing reactive C=N bonds, provides an opportunity towards further functionalization. Indeed, a one-pot three-component condensation of alcohols, amines and phosphites, promoted by an iron-based Kn?lker-type complex in combination with a chiral BINOL-based phosphoric acid, provides access to enantioenriched α-N-alkylaminophosphonates.
Synthesis of Cyclic N-Hydroxylated Ureas and Oxazolidinone Oximes Enabled by Chemoselective Iodine(III)-Mediated Radical or Cationic Cyclizations of Unsaturated N-Alkoxyureas
Peilleron, Laure,Retailleau, Pascal,Cariou, Kevin
supporting information, p. 5160 - 5169 (2019/11/11)
In this study we describe the reactivity of unsaturated N-alkoxyureas in the presence of different combinations of a hypervalent iodine(III) reagent and a bromide source or TEMPO. Three complementary cyclizations can be achieved depending on the reaction conditions. On the one hand, PIFA with pyridinium bromide leads to an oxybromination reaction. On the other hand, bis(tert-butylcarbonyloxy)iodobenzene with tetrabutylammonium bromide or TEMPO triggers aminobromination or aminooxyamination reactions, respectively. Control experiments showed that the three reactions proceed through distinct mechanisms: the first process is ionic while the other two follow a radical manifold. (Figure presented.).
Intramolecular alkene electrophilic bromination initiated ipso -bromocyclization for the synthesis of functionalized azaspirocyclohexadienones
Yin, Qin,You, Shu-Li
, p. 3526 - 3529 (2012/07/31)
Intramolecular alkene electrophilic bromination initiated dearomative cyclization has been realized in the presence of DBDMH to provide functionalized azaspirocyclohexadienones in excellent yields under mild conditions.
Iridium-catalyzed, asymmetric amination of allylic alcohols activated by lewis acids
Yamashita, Yasuhiro,Gopalarathnam, Apsara,Hartwig, John F.
, p. 7508 - 7509 (2008/02/11)
The direct, Ir-catalyzed, regio- and enantioselective amination of allylic alcohols with Lewis acid activators to form branched allylic amine products is reported. The reactions of arylamines, benzylic amines, and secondary aliphatic amines in the presence of Nb(OEt)5 as activator occurred with high regioselectivities and high enantioselectivities. These results led to the development of Ir-catalyzed reactions of allylic alcohol with arylamines and BPh3 as activator in catalytic amounts. These reactions are rare examples of enantioselective substitutions of allylic alcohols. They are particularly unusual examples of the substitution of allylic alcohols to generate branched substitution products from monosubstituted allylic alcohols and of enantioselective substitutions of allylic alcohols with amine nucleophiles. Copyright
A simple iridium catalyst with a single resolved stereocenter for enantioselective allylic amination. Catalyst selection from mechanistic analysis
Leitner, Andreas,Shekhar, Shashank,Pouy, Mark J.,Hartwig, John F.
, p. 15506 - 15514 (2007/10/03)
A study of the relationship between the stereochemical elements of a phosphoramidite ligand and the stereoselectivity of iridium-catalyzed amination of allylic carbonates is reported. During catalyst activation, a complex of a phosphoramidite ligand possessing one axial chiral binaphtholate group and two resolved phenethyl substituents converts to a more reactive cyclometalated complex containing one distal chiral substituent at nitrogen, one substituent that becomes part of the metalacycle, and one unperturbed binaphtholate group. Systematic changes were made to the different stereochemical elements. Replacement of the distal chiral phenethyl substituent with a large achiral cycloalkyl group led to a catalyst that reacts with rates and enantioselectivities that are similar to those of the original catalyst with the phenethyl group. Studies of the reactions of diastereomeric ligands containing (R) or (S) binaphtholate groups on phosphorus, along with one (R)-phenethyl and one achiral cyclododecyl group on nitrogen, show that the complexes of the two diastereomeric ligands undergo cyclometalation at much different rates. To access both diastereomeric catalysts and to determine if the reaction can occur selectively with an even simpler ligand containing a phenethyl substituent at nitrogen as the only resolved stereochemical element, the catalyst derived from a phosphoramidite containing a biphenolate group was studied. Catalysts generated from this ligand were shown to react in all cases examined with nearly the same rates, regioselectivities, and enantioselectivities as catalysts derived from the original more elaborate ligand. The absolute stereochemistry of the product implies that the major enantiomer is formed from the (R a,Rc)-atropisomer of the catalyst containing the biphenolate group.
ENANTIOSELECTIVE AMINATION AND ETHERIFICATION___________________
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Page 17-19; 38-39, (2010/02/06)
The present invention is directed to a catalyst composition, comprising: (1) a catalyst precursor having the general structure MSXn wherein M is a transition metal selected from the group consisting of iridium, molybdenum, and tungsten; S is a coordinating ligand; X is a counterion; and n is an integer from 0 to 5; and (2) a phosphoramidite ligand having the structure wherein O-Cn-O is an aliphatic or aromatic diolate and wherein R1, R2, R3 and R4 are selected from the group consisting of substituted or unsubstituted aryl groups, substituted or unsubstituted heteroaryl groups, substituted or unsubstituted aliphatic groups, and combinations thereof, with the proviso that at least one of R1, R2, R3, or R4 must be a substituted or unsubstituted aryl or heteroaryl group. The present invention is also directed to activated catalysts made from the above catalyst composition, as well as methods of allylic amination and etherification using the above catalysts.
A convenient preparation of allylic amines
Breuilles,Kaspar,Uguen
, p. 8011 - 8014 (2007/10/02)
Addition of aldehydes to the bis-lithio derivative of aminosulfone 1, followed by treatment of the resulting mixture with N,N'-carbonyl dimidazole gave phenylsulfonyloxazinones. Reduction by Na/Hg then afforded almost pure (E)-allylamines.
