A New Synthesis Of Substituted Allenes From Enones And Total Synthesis Of (±)-13-Epineostenine

The thesis comsists of the following two main parts: a new metal-free, one-pot synthesis of substituted allenes from enones and an efficient total synthesis of (±)-13-Epineostenine.Part I : A new metal-free, one-pot synthesis of substituted allenes from enones was developed for the first time, in which a tertiary amine as a base was found to be an effective promoter in such novel transformations. The present synthetic protocol proceeded readily with high compatibility of various sensitive functional groups, and it provides a new efficient way to access a series of synthetically important allenes without the use of metallic reagents or catalysts.Part II: An efficient total synthesis of (±)-13-epineostenine has been achieved in 15 steps and 17% overall yield. This approach involved the key aklylation/Michael addition of the central 1,4-cyclohexanedione monoethylene acetal, and all of the stereocenters on central cyclohexane were constructed in highly stereoselectivity.