Enantioselective synthesis of substituted pyrans via amine-catalyzed Michael addition and subsequent enolization/cyclisation
作者:Utpal Das、Chan-Hui Huang、Wenwei Lin
DOI:10.1039/c2cc31445b
日期:——
An organocatalytic construction of optically enriched substituted pyran derivatives via amine-catalyzed Michael addition and subsequent enolization/cyclisation has been described starting from electronically poor alkenes. Functionalized pyrans were obtained in high enantioselectivities (up to 96%) and good yields (up to 90%) having three contiguous chiral centers.
Organocatalytic asymmetric synthesis of highly substituted pyrrolidines bearing a stereogenic quaternary centre at the 3-position
作者:Soumendranath Mukhopadhyay、Subhas Chandra Pan
DOI:10.1039/c8ob02648c
日期:——
An organocatalyticasymmetric cascade reaction has been developed for the synthesis of highlysubstituted pyrrolidines having a stereogenic quaternary centre at the 3-position. N-Tosyl aminomethyl enone and trans-α-cyano-α,β-unsaturated ketone were utilized as the reaction partners in this method. Cinchonidine derived bifunctional amino-squaramide catalysts were the best to obtain the products in high
Phosphine-catalyzed [3 + 2] annulation of β-sulfonamido-substituted enones with <i>trans</i>-α-cyano-α,β-unsaturated ketones for the synthesis of highly substituted pyrrolidines
To synthesize highly substituted pyrrolidines, we developed a phosphine-catalyzed [3 + 2] annulation of β-sulfonamido-substituted enones with trans-α-cyano-α,β-unsaturated ketones. We prepared a series of pyrrolidines under mild conditions with high yields and moderate-to-good diastereoselectivities. A catalytic mechanism for this reaction is suggested.