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
The organocatalytic enantio- and diastereoselective cycloetherification of 1,3-cyclohexanedione-bearing enones involving the in situ generation of chiral cyanohydrins was developed. This transformation offers the first catalytic asymmetric approach to oxadecalin derivatives containing contiguous tetrasubstituted chiral carbons at the bridge heads of the fused ring systems. Depending on substituents
The addition of 0.5 equiv of TiCl4 to (cyclo)alkanones tethered to alpha,beta-unsaturated ketones afforded polyfunctionalized diquinanes, hydrindanes, and decalines. These products, resulting from a Michael-aldol or a Baylis-Hillman reaction, can be obtained with high or total diastereoselectivity in moderate to high yields. These scaffolds represent interesting building blocks for the synthesis of complex natural products.