α′-acetoxy α,β-unsaturated cyclopentanone and cyclohexanone have been resolved into the corresponding enantiomericallyenriched α′-hydroxylated and acetoxylated compounds with 96–97% ee via PLE hydrolysis. Stereoselectivity in the palladium(II)-catalyzed reaction between the enantiomericallyenriched α′-acetoxylated compounds and diazomethane has been investigated. In the α′-acetoxylated cyclopentenone
Stereoselective synthesis of optically active cyclitol precursors via a chemoenzymatic method
作者:Funda Oğuzkaya、Ertan Şahin、Cihangir Tanyeli
DOI:10.1016/j.tetasy.2006.11.002
日期:2006.11
Racemic α′-acetoxy α,β-unsaturated cyclohexanone has been converted to the corresponding enantiomerically enriched α′-hydroxylated and acetoxylated compounds with 97% ee via enzymatic resolution with PLE. OsO4-Catalyzed dihydroxylation of enantiomerically enriched α′-acetoxylated compound afforded a single diastereomer in 85% chemical yield. The absolute configuration of 2,3,6-triacetoxycylohexanone
Toward the synthesis of antascomicin B. Synthesis of a model of the C22–C34 fragment via Ireland–Claisen and allylic diazene rearrangements
作者:Wei Qi、Matthias C. McIntosh
DOI:10.1016/j.tet.2008.05.070
日期:2008.7
The C22-C34 fragment of antascomicin B lacking the C31 and C32 hydroxyl groups has been prepared in 11 steps from commercially available 2-hydroxy-cyclohexanone. An Ireland-Claisen rearrangement was employed to install the C26 and C27 stereocenters. Our recently reported diastereoselective acyclic 1,3-reductive transposition was used to establish the remote C23 stereocenter. Directed hydrogenation was employed to set the C29 stereocenter. The model compound contains five of the stereocenters and all of the carbons of the corresponding fragment of antascomicin B. (C) 2008 Elsevier Ltd. All Fights reserved.
Total synthesis of (+)-blennolide C and (+)-gonytolide C via spirochromanone
We report the asymmetric total synthesis of (+)-blennolide C and (+)-gonytolide C isolated from endophytic fungi. The synthesis involved construction of a spirochromanone with a chiral quaternary carbon by the aldolreaction of o-hydroxyacetophenones and optically active α-oxygenated cyclohexenone, followed by cyclization under acidic conditions. Oxidative cleavage of the alkene moiety of the spirochromanone
Dehydrogenative Coupling to Enable the Enantioselective Total Synthesis of (−)-Simaomicin α
作者:Yizhong Wang、Chao Wang、John R. Butler、Joseph M. Ready
DOI:10.1002/anie.201304812
日期:2013.10.4
The anticancer natural product simaomicin α has been synthesized. Asymmetric synthesis allowed the assignment of absolute stereochemistry. The enantiomer of the naturally occurring substance shows potent cytotoxicity towards Gram‐positive bacteria and human cancer cells. Bn=benzyl, BOM=benzyloxymethyl.