Studies on the Base-Promoted Conversion of Conjugated Alkynyl Esters to α-Substituted α-Allenyl Esters
作者:Salvatore D. Lepore、Yuanjun He、Pamela Damisse
DOI:10.1021/jo0487754
日期:2004.12.1
variety of conjugated alkynyl esters to α-substituted conjugated allenyl esters (racemic) through the use of strong amide bases. Substantially improved yields over typical enolate formation conditions were observed with the use of 2 equiv of lithium diisopropylamide. Trapping studies indicate that the second equivalent of base likely leads to the dianion intermediate, which upon addition of methyl iodide
Michael−Stork Addition of Cyclopentyl Enamine to Allenyl Ketones and Esters
作者:Maximilian A. Silvestri、Deborah C. Bromfield、Salvatore D. Lepore
DOI:10.1021/jo0512103
日期:2005.9.1
We report the first examples of a Michael−Stork enamine addition to allenyl esters and ketones. Studies reveal that 2 equivalents of enamine are required for optimal yields. In the case of an allenyl methylketone, cyclopentyl enamine addition led to 8-oxobicyclo[3.2.1]octane formation, providing evidence for the in situ formation of an enamine intermediate following the initial Michael−Stork reaction