- Enantioselective iridium-catalyzed allylic amination of ammonia and convenient ammonia surrogates
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Iridium-catalyzed, asymmetric allylation of ammonia as a nucleophile occurs with stereoselectivity to form a symmetric dialiylamine, and related allylation of the inexpensive ammonia equivalent potassium trifluoroacetamide or the highly reactive ammonia equivalent lithium ditert-butyliminodicarboxylate forms a range of conveniently protected, primary, a-branched allylic amines in high yields, high branched-to-linear regioselectivities, and high enantiomeric excess. The reactions of ammonia equivalents were conducted with a catalyst generated from a phosphoramidite containing a single stereochemical element.
- Pouy, Mark J.,Leitner, Andreas,Weix, Daniel J.,Ueno, Satoshi,Hartwig, John F.
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- Iridium-catalyzed asymmetric allylic amination with polar amines: Access to building blocks with lead-like molecular properties
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The combination of an air-stable iridium catalyst and the dipolar aprotic solvent dimethyl sulfoxide (DMSO) allowed, for the first time, the systematic exploitation of highly polar, functionalized amines in asymmetric allylic substitutions: low molecular
- Tosatti, Paolo,Horn, Joachim,Campbell, Amanda J.,House, David,Nelson, Adam,Marsden, Stephen P.
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supporting information; experimental part
p. 3153 - 3157
(2011/03/18)
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- Enantioselective synthesis of allylboronates bearing a tertiary or quaternary B-substituted stereogenic carbon by NHC-Cu-catalyzed substitution reactions
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Allylic substitutions that afford α-substituted allylboronates bearing B-substituted tertiary or quaternary carbon stereogenic centers are presented. C-B bond-forming reactions, catalyzed by chiral bidentate Cu-NHC complexes, are performed in the presence of commercially available bis(pinacolato)diboron. Transformations proceed in high yield (up to >98%) and site selectivity (>98% SN2′), and in up to >99:1 enantiomer ratio. Trans- or cis-disubstituted alkenes can be used; alkyl- (linear as well as branched) and aryl-trisubstituted allylic carbonates serve as effective substrates. Allylboronates that bear a quaternary carbon center are air-stable and can be easily purified by silica gel chromatography; in contrast, secondary allylboronates cannot be purified in the same manner and are significantly less stable. Oxidation of the enantiomerically enriched products furnishes secondary or tertiary allylic alcohols, valuable small molecules that cannot be easily obtained in high enantiomeric purity by alternative synthesis or kinetic resolution approaches.
- Guzman-Martinez, Aikomari,Hoveyda, Amir H.
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supporting information; scheme or table
p. 10634 - 10637
(2010/11/05)
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