Cooperative catalysts consisting of chiral Rh/Ag nanoparticles and Sc(OTf)3 have been developed that catalyze asymmetric 1,4-addition reactions of arylboronic acids with α,β-unsaturated amides efficiently. The reaction has been considered one of the most challenging reactions because of the low reactivity of the amide substrates. The new catalysts provide the desired products with outstanding enantioselectivities (>98 % ee) in the presence of low loadings (<0.5 mol %) of the catalyst.
Novel chiral macrocyclic aromatic amides of medium molecular weight were synthesized by the one-step amide coupling of a bis(alkylamino)terphenyl diacid as monomer.
The activation energies of the shuttling of [2]rotaxanes with various N‐arylpyrrole moieties were determined by variable temperature (VT) 1H NMR experiments. The value provided a new quantitative scale for the estimation of the steric bulk of the substituents. The rigidity and the electronic effect of the substituents, which could inadequately influence the estimation of the steric bulk, were minimized in the method we presented.
Cooperative catalysts consisting of chiral Rh/Ag nanoparticles and Sc(OTf) 3 have been developed that catalyze asymmetric 1,4-addition reactions of arylboronic acids with a,b-unsaturated amides efficiently. The reaction has been considered one of the most challenging reactions because of the low reactivity of the amide substrates. The new catalysts provide the desired products with outstanding enantioselectivities (> 98 % ee) in the presence of low loadings (< 0.5 mol %) of the catalyst. Table 3: Recovery and reuse of the catalyst. Parameter Run 1 [c] 2 [d] 3 [d] 4 [e] 5 [e]Yield (%) [a] 87 (1.32 g) 82 53 75 75 ee (%) [b] 99 99
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