Model Studies To Access the [6,7,5,5]-Core of Ineleganolide Using Tandem Translactonization–Cope or Cyclopropanation–Cope Rearrangements as Key Steps

Abstract

Recently, we reported a convergent cyclopropanation-Cope approach to the core of ineleganolide, which was the first disclosed synthesis of the core of the norditerpene natural product ineleganolide. In this complementary work, a model system for the core of ineleganolide has been prepared through a series of tandem cyclopropanation-Cope and translactonization-Cope rearrangements. Work with this model system has enriched our understanding of the cyclopropanation-Cope rearrangement sequence. Additionally, research into this model system has driven the development of tandem translactonization-Cope rearrangements.

Small rings in the bigger picture: ring expansion of three- and four-membered rings to access larger all-carbon cyclic systems

“…More precisely, they developed a straightforward access to the [6,7,5,5] tetracyclic core of ineleganolide (130 ). 104 Three complementary domino sequences were reported by the authors. To get straight to the point, the divinylcyclopropane 131 could not undergo, as anticipated, a direct Cope rearrangement since it would lead to a highly strained embedded cycloheptadiene 132, presenting two anti Bredt bridgehead alkene (Scheme 43).…”

Diazocarbonyl and Related Compounds in the Synthesis of Azoles

“…The synthesis of 5-arylsubstituted pyrazoles by the one-pot diazo transfer-cyclization approach has also been reported [ 105 ]. Separate examples of cyclization of vinyldiazo compounds to pyrazoles are presented in a number of works by other authors [ 106 , 107 , 108 , 109 , 110 , 111 ].…”

Unified Enantioselective, Convergent Synthetic Approach toward the Furanobutenolide-Derived Polycyclic Norcembranoid Diterpenes: Synthesis of a Series of Ineleganoloids by Oxidation-State Manipulation of the Carbocyclic Core

“…Previously, we developed an enantioselective and diastereoselective approach toward the synthesis of the furanobutenolide-derived polycyclic norditerpenoids, resulting in synthetic access to the enantioenriched [6,7,5,5]-tetracyclic core of ent -ineleganolide ( ent -1 ) and representing the first completion of the carbocyclic scaffold of any member of the polycyclic furanobutenolide-derived norcembranoid natural product family (Scheme ). , Completion of ent -ineleganolide ( ent -1 ) from ent - epi -isoineleganolide B ( 6 ), envisioned through olefin isomerization and ultimately intramolecular oxa-Michael addition from vinylogous diketone 7 , proved untenable . Nevertheless, with synthetic access to the [6,7,5,5]-tetracyclic core of ent -ineleganolide ( ent -1 ) established, we sought to develop an alternative late-stage strategy that would enable access to the natural product itself.…”