An Approach to a Bislactone Skeleton: A Scalable Total Synthesis of (±)-Penifulvin A

An efficient and scalable total synthesis of the architecturally challenging sesquiterpenoid (±)-penifulvin A has been accomplished via a 12-step sequence with an overall yield of 16%. For the construction of this structurally complex tetracyclic molecule, the key steps used included 1,4-conjugate addition, a Pd(0) catalyzed cross-coupling reaction between an enol phosphate and trimethyl aluminum, Claisen rearrangement using the Johnson orthoester protocol, Ti­(III)-mediated reductive epoxide opening–cyclization, Lewis acid catalyzed epoxy-aldehyde rearrangement, and finally a substrate controlled oxidative cascade lactonization process

Application of Cp₂TiCl-Promoted Radical Cyclization: A Unified Strategy for the Syntheses of Iridoid Monoterpenes

An expedient approach toward the unified total syntheses of (+)-iridomyrmecin, (−)-isoiridomyrmecin, (+)-7-<i>epi</i>-boschnialactone, (+)-teucriumlactone, and (−)-dolichodial in chirally pure forms starting from readily available (+)-β-citronellene is delineated combining step economy and simplicity. Highlights include a Ti­(III)-mediated reductive epoxide opening-cyclization for the construction of the core cyclopenta­[<i>c</i>]­pyran skeleton of the iridoid lactones with complete diastereoselectivity for the newly created bridgehead stereogenic centers. Subsequent transformations facilitate a short access to (+)-teucriumlactone and (−)-dolichodial and formal access to potentially other iridoids

Application of Cp₂TiCl-Promoted Radical Cyclization: A Unified Strategy for the Syntheses of Iridoid Monoterpenes

An expedient approach toward the unified total syntheses of (+)-iridomyrmecin, (−)-isoiridomyrmecin, (+)-7-<i>epi</i>-boschnialactone, (+)-teucriumlactone, and (−)-dolichodial in chirally pure forms starting from readily available (+)-β-citronellene is delineated combining step economy and simplicity. Highlights include a Ti­(III)-mediated reductive epoxide opening-cyclization for the construction of the core cyclopenta­[<i>c</i>]­pyran skeleton of the iridoid lactones with complete diastereoselectivity for the newly created bridgehead stereogenic centers. Subsequent transformations facilitate a short access to (+)-teucriumlactone and (−)-dolichodial and formal access to potentially other iridoids