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Please login to access the full content or check if you have access via5.4.3.4.4 Intermolecular Chloroamination Catalyzed by Scandium(III) Lewis Acids
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Andries-Ulmer, A.; Gulder, T., Science of Synthesis: Catalytic Oxidation in Organic Synthesis, (2017) 1, 424.
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.[99–102]
Meeee 88 Meeeeeeeeeeeeee ee α,β-Meeeeeeeeee Meeeeee Meeeeeeee ee Meeeeeee(MMM) M-Meeeee[88]
Meeeeeeee | Meeeeee | eee (%) | Meeee (%) | Mee |
---|---|---|---|---|
88 | 88 | [88] | ||
88 | 88e | [88] | ||
88 | 88 | [88] | ||
88 | 88 | [88] |
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α-Meeeee-β-Meeee Meeeeee 88; Meeeeee Meeeeeeee:[88]
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References
[96] | Mee, M.; Mee, M.; Meeee, M.; Meee, M.; Mee, M.; Meee, M., M. Me. Meee. Mee., (8888) 888, 8888. |
[97] | Mee, M.; Mee, M.; Mee, M.; Meeee, M.; Meee, M.; Meee, M.; Mee, M.; Meee, M., Meeee. Meee. Mee. Me., (8888) 88, 8888. |
[98] | Mee, M.; Mee, M.; Me, M.; Meee, M.; Meee, M.; Mee, M.; Meee, M., Meee.–Mee. M., (8888) 88, 88888. |
[99] | Me, M.; Mee, M., Mee. Meee., (8888) 88, 8888. |
[100] | Meeee, M.; Mee, M.; Mee, M.; Mee, M.; Meee, M.; Mee, M., Mee. Meeeee. Meee., (8888) 88, 8888. |
[101] | Mee, M.; Mee, M.; Meee, M.; Mee, M., Mee. Meee., (8888) 88, 8888. |
[102] | Mee, M.; Meeee, M.; Mee, M.; Meee, M.; Mee, M., Mee. Meee., (8888) 88, 888. |