866023-01-0Relevant academic research and scientific papers
Regio- and enantioselective allylic amination of achiral allylic esters catalyzed by an iridium-phosphoramidite complex
Ohmura, Toshimichi,Hartwig, John F.
, p. 15164 - 15165 (2002)
A new catalytic asymmetric process, the iridium-catalyzed enantioselective allylic amination of (E)-cinnamyl and terminal aliphatic allylic carbonates, was developed by exploring complexes of chiral phosphoramidites. The reaction provided branched secondary and tertiary allylic amines in high yields with excellent regio- and enantioselectivity (13 examples over 94% ee). Although the reactions in polar solvent such as DMF, EtOH, and MeOH were fast, they gave low enantiomeric excesses. In contrast, reactions in THF displayed the most suitable balance of rate and enantioselectivity. Both the binaphthol unit and the disubstituted amine in the phosphoramidite affected reactivity and selectivity, and complexes of O,O′-(R)-(1,1′-dinaphthyl-2,2′-diyl)-N,N′-di-(R,R)-1-phenylethylphosphoramidite provided the highest reactivity and selectivity. Primary and cyclic secondary amines reacted at room temperature, and acyclic diethylamine reacted at 50 °C. p-Methoxy-substituted cinnamyl carbonate reacted similarly to the unsubstituted cinnamyl carbonate, but the o-methoxy-substituted substrate gave lower enantiomeric excess. High ee's were also observed for the products from the reaction of furanyl- and alkyl-substituted (E)-allylic carbonates. Copyright
Diastereodivergent hydroxyfluorination of cyclic and acyclic allylic amines: Synthesis of 4-deoxy-4-fluorophytosphingosines
Cresswell, Alexander J.,Davies, Stephen G.,Lee, James A.,Morris, Melloney J.,Roberts, Paul M.,Thomson, James E.
, p. 7262 - 7281 (2012/10/30)
A diastereodivergent hydroxyfluorination protocol enabling the direct conversion of some conformationally biased allylic amines to the corresponding diastereoisomeric amino fluorohydrins has been developed. Sequential treatment of a conformationally biased allylic amine with 2 equiv of HBF 4·OEt2 followed by m-CPBA promotes epoxidation of the olefin on the face proximal to the amino group under hydrogen-bonded direction from the in situ formed ammonium ion. Regioselective and stereospecific epoxide ring-opening by transfer of fluoride from a BF 4- ion (an SN2-type process at the carbon atom distal to the ammonium moiety) then occurs in situ to give the corresponding amino fluorohydrin. Alternatively, an analogous reaction using 20 equiv of HBF4·OEt2 results in preferential epoxidation of the opposite face of the olefin, which is followed by regioselective and stereospecific epoxide ring-opening by transfer of fluoride from a BF 4- ion (an SN2-type process at the carbon atom distal to the ammonium moiety). The synthetic utility of this methodology is demonstrated via its application to a synthesis of 4-deoxy-4-fluoro-l-xylo- phytosphingosine and 4-deoxy-4-fluoro-l-lyxo-phytosphingosine, each in five steps from Garner's aldehyde.
Effects of catalyst activation and ligand steric properties on the enantioselective allylation of amines and phenoxides
Leitner, Andreas,Shu, Chutian,Hartwig, John F.
, p. 1093 - 1096 (2007/10/03)
(Chemical Equation Presented) The yields, enantioselectivities, and regioselectivities of the reactions of amines and phenoxides with allylic carbonates in the presence of a metallacyclic iridium catalyst were compared. These data show that both preactiva
Synthesis of sultams by intramolecular Heck reaction
Merten, Sandra,Froehlich, Roland,Kataeva, Olga,Metz, Peter
, p. 754 - 758 (2007/10/03)
A novel access to α-methylene-γ-sultams via the intramolecular Heck reaction of α-bromovinylsulfonamides derived from allylic amines is reported. These heterocycles are potent Michael acceptors towards sulfur nucleophiles.
ENANTIOSELECTIVE AMINATION AND ETHERIFICATION___________________
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Page 17-19; 44, (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.
