%0 Journal Article %A Yu, Min %A Pochapsky, Susan S. %A Snider, Barry B. %D 2008 %T Synthesis of 7-Epineoptilocaulin, Mirabilin B, and Isoptilocaulin. A Unified Biosynthetic Proposal for the Ptilocaulin and Batzelladine Alkaloids. Synthesis and Structure Revision of Netamines E and G %U https://acs.figshare.com/articles/journal_contribution/Synthesis_of_7_Epineoptilocaulin_Mirabilin_B_and_Isoptilocaulin_A_Unified_Biosynthetic_Proposal_for_the_Ptilocaulin_and_Batzelladine_Alkaloids_Synthesis_and_Structure_Revision_of_Netamines_E_and_G/2898385 %R 10.1021/jo801956w.s001 %2 https://acs.figshare.com/ndownloader/files/4596526 %K Synthesi %K guanidine %K intramolecular Michael reaction %K netamine E %K isoptilocaulin %K side chains trans %K MnO 2 oxidation %K dehydroptilocaulin oxidation state %K tricyclic %K epineoptilocaulin %K Unified Biosynthetic Proposal %K enone %K Hydride %X Addition of guanidine to a 6-methylhexahydroindenone in MeOH at 85 °C afforded 7-epineoptilocaulin. A similar reaction with a 6-propylhexahydroindenone afforded netamine E. MnO2 oxidation of 7-epineoptilocaulin and netamine E afforded mirabilin B and netamine G, respectively. The netamines have the side chains trans, not cis as was initially proposed. A unified biosynthetic scheme for the batzelladines and ptilocaulin family is proposed. Conjugate addition of guanidine to a bis enone followed by an intramolecular Michael reaction of the enolate to the other enone, aldol reaction, dehydration, and enamine formation will lead to a tricyclic intermediate at the dehydroptilocaulin oxidation state. 1,4-Hydride addition will lead to ptilocaulin or 7-epineoptilocaulin depending on which face the hydride adds to. 1,2-Hydride addition will lead to isoptilocaulin. The key tricyclic intermediate was prepared from a tetrahydroindenone and guanidine and reduced with NaBH4 to give a mixture rich in ptilocaulin and isoptilocaulin. %I ACS Publications