Unsaturated nine-membered ring lactams that contain (E)-olefins within the ring are characterized by planar chiral properties. Thus, selective conversions of the double bond allowed a complete transfer of the planar chiral information into new stereogenic centers The basis of the transformations was the high activation barrier that prevented efficient flipping of the double bond at room temperature (epimerization
Planar Chirality: Synthesis and Transannular Reactions of Unsaturated Optically Active Azoninones Bearing <i>E</i>-Olefins
作者:Alexander Sudau、Winfried Münch、Udo Nubbemeyer、Jan W. Bats
DOI:10.1021/jo991484o
日期:2000.3.1
zwitterionic aza-Claisen rearrangement of opticallyactive trans 4-silyloxy-2-vinylpyrrolidines and carboxylic acid fluoride generated nine-membered ring lactams with high yields. The reaction proceeded with an almost complete 1,4-chirality transfer and the exclusive generation of the E-double bond in the medium sized rings to cause additional planar chiral information. The initially formed azoninones