Synthesis of the Ring System of Phomactin D Using a Suzuki Macrocyclization
作者:Nicholas C. Kallan、Randall L. Halcomb
DOI:10.1021/ol0062345
日期:2000.8.1
text]The ring system of phomactin D was synthesized in racemic form in an efficient manner from 2,3-dimethylcyclohexanone. Notable transformations include (1) an alkylation of the enolate of a vinylogous thiolester to install a quaternary stereocenter, (2) a conjugate addition of cyanide to an alpha,beta-unsaturated aldehyde, (3) the formation of a Weinreb amide directly from a cyanohydrin, and (4) an intramolecular
Acyclic 1,4-Stereocontrol via Reductive 1,3-Transpositions
作者:Wei Qi、Matthias C. McIntosh
DOI:10.1021/ol702921x
日期:2008.1.1
One-pot reduction/allylic diazene rearrangement of lactic acid- and mandelic acid-derived alpha,beta-unsaturated tosyl hydrazones leads to 1,4-syn- or 1,4-anti-E-2-alkenyl arrays in high yield and diastereoselectivity. Either the syn or the anti diastereomer can be prepared by choosing the appropriate alkene stereoisomer of the hydrazone. The E-alkenes led to the 1,4-syn isomers, while the Z-alkenes led to the 1,4-anti isomers, both with >= 20:1 diastereoselectivity.