Development of Acyl and Silyl Group Transfer Reactions of Ketene Acetal Derivatives and Their Applications to the Synthesis of Natural Products

点击翻译按钮获取中文摘要

In organic synthesis, reagents are required which are able under neutral or nearly neutral conditions to bring about the desired reactions in high yields with easy isolation. For this purpose, ketene acetal derivatives 1 were suitably introduced as the reagents for alkoxycarbonylation, silylation, silylenation, carboxylic anhydride-formation, and the silyl group-transfer addition reactions from this laboratory.In connection with this study, we have established the synthesis of 2-deoxy-D-ribose from 2,3-O-isopropylidene-D-glyceraldehyde and N-benzoyl-1-daunosamine from (2)-[(4s)-trans-2,2,5-trimethyl-1,3-dioxolan-4-yl]methylene-[(1s)-1-phenylethyl]amine-N-oxide utilizing the silyl group-transfer addition reactions of o-silylated ketene acetal (1a). Furthermore, we have found that the treatment of sulfoxide with 1a caused a Pummerer-type rearrangement under nearly neutral conditions. As an extension of the reaction, we applied the reaction to a novel and efficient intramolecular Pummerer-type rearrangement of <omega>-amidosulfoxides which gave the 4 to 7-membered -thiolactams in high yields. Further studies on the annelation reactions of some sulfoxides haveing <omega>-olefinic substituents are in progress.