A Formal Total Synthesis of (+)-Zincophorin. Observation of an Unusual Urea-Directed Stork−Crabtree Hydrogenation
摘要:
A formal total synthesis of (+)-zincophorin via interception of Miyashita's advanced intermediates is described here. This effort features the first synthetic application of an inverse demand hetero [4 + 2] cycloaddition of a chiral allenamide, and the observation of an unusual urea directed Stork-Crabtree hydrogenation.
Studies on a Urea-Directed Stork−Crabtree Hydrogenation. Synthesis of the C1−C9 Subunit of (+)-Zincophorin
摘要:
[GRAPHICS]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.