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Please login to access the full content or check if you have access via Intermolecular Chloroamination Catalyzed by Scandium(III) Lewis Acids

DOI: 10.1055/sos-SD-225-00195

Andries-Ulmer, A.; Gulder, T.Science of Synthesis: Catalytic Oxidation in Organic Synthesis, (20171424.

Excellent enantioselectivities (93–98% ee) can be achieved in intermolecular haloaminations if scandium(III) complexes are employed as chiral Lewis acids. For example, chalcones and α,β-unsaturated γ-oxo esters 94 undergo rapid conversion into 3-amino-2-chloro ketones 96 in the presence of low amounts (0.05 mol%) of both scandium(III) trifluoromethanesulfonate and the C2-symmetric N-oxide 95 together with N,N-dichloro-4-toluenesulfonamide as the electrophilic chlorine species (Table 10).[‌96‌] Unfortunately, only 4-toluenesulfonamide is reported as nucleophile for this method. The corresponding bromo- and iodoaminations are likewise possible after slight alterations of the reaction conditions.[‌97‌,‌98‌] Intramolecular processes can be triggered by scandium(III) complexes as well. In such bromoaminocyclizations, chiral phosphine ligands appear to be the best choice.[‌99‌‌102‌]

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