Studies on a Urea-Directed Stork−Crabtree Hydrogenation. Synthesis of the C1−C9 Subunit of (+)-Zincophorin
journal contributionposted on 07.12.2007, 00:00 by Zhenlei Song, Richard P. Hsung, Ting Lu, Andrew G. Lohse
A detailed account on the stereoselective synthesis of the C1−C9 subunit of (+)-zincophorin is described here. This approach features the first application of a stereoselective inverse electron demand hetero-[4 + 2] cycloaddition of chiral allenamides in natural product synthesis. The C1−C9 subunit matches Cossy's intermediate, thereby constituting a formal total synthesis. In addition, details of an unusual urea-directed Stork−Crabtree hydrogenation observed during these efforts are also disclosed here.