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
Organocatalytic Asymmetric Synthesis of Pentasubstituted Tetrahydrothiopyrans Bearing a Quaternary Centre through a Double Michael Reaction
作者:Subhas Pan、Buddhadeb Mondal
DOI:10.1055/s-0036-1591736
日期:2018.3
An organocatalytic, asymmetric, double-Michael strategy has been developed employing trans-α-cyano-α,β-unsaturated ketones for the synthesis of pentasubstituted tetrahydrothiopyrans bearing a quaternary center. A proline-derived bifunctional thiourea was found to be the most effective catalyst for this reaction. With 10 mol% of catalyst, good yields and good to high diastereomeric ratios, as well as
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.
Stereocontrolled routes to derivatives of 3-alkoxycarbonyl-2-amino-4-aryl-5-cyano-6-phenyl-4H-pyrans
作者:Nazario Martín、Angeles Martínez-Grau、Carlos Seoane、JoséL. Marco
DOI:10.1016/0957-4166(94)00382-l
日期:1995.1
The asymmetric Michael addition of cyanoacetates 2b-e and benzoylacetonitrile 6 to alpha-benzoylcinnamonitrile 3 and alpha-cyanocinnamates 7b-e, respectively, has been studied. The resulting 3-alkoxycarbonyl-2-amino-4-aryl-5-cyano-6-phenyl-4H-pyrans 4b-e have been obtained in moderate diastereomeric excess and good chemical yield.