Intramolecular reductive coupling of cycloalkanones tethered to alkynoates in the presence of (η2-propene)titanium was successfully performed to provide hydroxy-esters in a diastereoselective manner. Subsequent lactonization afforded angularly fused unsaturated tricyclic lactones which represent relevant substructures of numerous bioactive compounds.
Enantioselective Synthesis of Quaternary Carbon Stereogenic Centers through the Primary Amine-Catalyzed Michael Addition Reaction of α-Substituted Cyclic Ketones at High Pressure
The enantioselectiveMichaeladditionreaction of α-substitutedcyclicketones with acrylates was efficiently promoted by a primary amine chiral catalyst under high-pressure conditions (1.0 GPa) in tetrahydrofuran. This method was highly successful for the construction of an all-carbon-substituted quaternary-carbon stereogeniccenter at the α-position of cyclicketones in high enantiomeric excess,
Enantioselective Formal Total Synthesis of (−)-Dysidiolide
作者:Michael E. Jung、Nobuko Nishimura
DOI:10.1021/ol016073k
日期:2001.6.1
[reaction: see text] An enantioselective formal totalsynthesis of the sesterterpene (-)-dysidiolide 1 beginning with an intermolecular Diels-Alder reaction of the allene ester 3 and the silyloxydiene 10 is reported.
Asymmetric Synthesis of Polyfunctionalized Allenic Esters: Toward the Synthesis of an Iphionane Sesquiterpene
作者:Michel Miesch、Aurélie Klein
DOI:10.1055/s-2006-942463
日期:2006.8
smoothly with optically active acetylenic ω-keto esters to afford optically active allenicesters (ee >95%) in high yield. After protection of the hydroxyl group, the addition of morpholine followed by an acidic hydrolysis, quantitatively led to optically active bicyclic α,β-unsaturated ketones (ee >95%). By using this methodology, the formal synthesis of an iphionane sesquiterpene was achieved.
higher investment in the development of the corresponding syntheses. This approach requires the development of complex multistep reaction sequences on the solid phase. Employing the proteinphosphatase Cdc25 inhibitor dysidiolide as an example, we demonstrate that this goal can be achieved successfully. The reaction sequences developed led to dysidiolide analogues in overall 8-12 linear steps with