Inversion of Diastereoselectivity Depending on Substrate Concentration in Baker’s Yeast Catalyzed Reduction of σ-Symmetrical 1,3-Cyclopentadiones and 1,3-Cyclohexadiones
Inversion of Diastereoselectivity Depending on Substrate Concentration in Baker’s Yeast Catalyzed Reduction of σ-Symmetrical 1,3-Cyclopentadiones and 1,3-Cyclohexadiones
An easy route toward enantio-enriched polycyclic derivatives via an asymmetric domino conjugate reduction–aldol cyclization catalyzed by a chiral Cu(I) complex
作者:Julia Deschamp、Thomas Hermant、Olivier Riant
DOI:10.1016/j.tet.2011.07.039
日期:2012.4
A highlyefficient reductive-aldol cyclization mediated by a chiral Cu(I) complex and an organosilane yielded to cyclic or polycyclic derivatives. An excellent control of the selectivities was reached in most cases (dr up to 100:0 and ee up to 95%). After developing the enantioselective intramolecular reductive-aldol methodology, this strategy was successfully used for the synthesis of a key intermediate
One-Pot Organocatalytic Enantioselective Michael–Michael–Aldol–Henry Reaction Cascade. A Facile Entry to the Steroid System with Six Contiguous Stereogenic Centers
作者:Dai-Huei Jhuo、Bor-Cherng Hong、Chun-Wei Chang、Gene-Hsiang Lee
DOI:10.1021/ol501011t
日期:2014.5.16
An expedited method has been developed for the enantioselective synthesis of highly functionalized steroid systems containingsixcontiguousstereogenic centers with high enantioselectivities (99% ee). The one-pot methodology comprises a cascade of organocatalytic Michael–Michael–aldol–Henry reactions of 7-nitrohept-3-en-2-one and 5-(1-methyl-2,5-dioxocyclopentyl)pent-2-enal. The structure and absolute
We describe a synthetic method for a bicyclo[2.2.1]heptane skeleton with two oxy-functionalized bridgehead carbons. This method involves an intermolecular Diels–Alder reaction using 5,5-disubstituted 1,4-bis(silyloxy)-1,3-cyclopentadienes, the diene structure of which has never been synthesized. Furthermore, the intramolecular Diels–Alder reaction using a diene bearing a dienophile moiety at the C-5