Concise stereoselective synthesis of marine sesterterpene, 16-deacetoxy-12-epi-scalarafuran acetate and its 14-epimer via intramolecular Diels–Alder addition

Oxygenated Terpenes from Indo-Pacific Nudibranchs: Scalarane Sesterterpenes from Glossodoris hikuerensis and 12-Acetoxy Dendrillolide A from Goniobranchus albonares

“…. These values, together with the recent stereoselective synthesis and X-ray study of a scalafuran derivative[14] suggest the absolute configurations shown in Figure1.…”

“…. These values, together with the recent stereoselective synthesis and X-ray study of a scalafuran derivative[14] suggest the absolute configurations shown inFigure 1.Compound 2 was isolated in trace amount and gave a molecular formula of C 27 H 40 O 4 by HRESIMS. The 1 H NMR spectrum displayed an aldehyde signal (δ H 10.02, d, J = 2.5 Hz), an olefinic proton (δ H 5.89, br s, H-16) as well as a distinctive AB system [δ H 2.57, t, J = 14.2 Hz (H-11a); 2.39, dd, J = 13.9, 2.1 Hz (H-11b)].…”

An Alternative Approach towards C-12 Functionalized Scalaranic Sesterterpenoids Synthesis of 17-Oxo-20-norscalaran-12α,19-O-lactone

“…While the first two challenges have been addressed successfully in several synthetic strategies, the introduction of oxygenated functional groups, especially in the C-12 position of the tetracyclic system still represents a relevant synthetic hurdle. Only few works on the synthesis of cycle B- [11] and C-functionalized [12][13][14][15][16] scalaranes have been reported since 2004. In particular, previous successful reports on the synthesis of C-12-functionalized scalaranes make use of ent-isocopalic compounds and assemble the D-cycle via a Diels-Alder cycloaddition approach [12][13][14][15] or employing an intramolecular Heck reaction of tricyclic cheilanthanes [16].…”

“…Only few works on the synthesis of cycle B- [11] and C-functionalized [12][13][14][15][16] scalaranes have been reported since 2004. In particular, previous successful reports on the synthesis of C-12-functionalized scalaranes make use of ent-isocopalic compounds and assemble the D-cycle via a Diels-Alder cycloaddition approach [12][13][14][15] or employing an intramolecular Heck reaction of tricyclic cheilanthanes [16]. The most successful example [15] demonstrates the synthesis of the C-12 functionalized scalaranic framework over 18 synthetic steps with an 4.5% overall yield.…”

“…In particular, previous successful reports on the synthesis of C-12-functionalized scalaranes make use of ent-isocopalic compounds and assemble the D-cycle via a Diels-Alder cycloaddition approach [12][13][14][15] or employing an intramolecular Heck reaction of tricyclic cheilanthanes [16]. The most successful example [15] demonstrates the synthesis of the C-12 functionalized scalaranic framework over 18 synthetic steps with an 4.5% overall yield. We present in the current paper an alternative synthetic rout towards the scalaranes functionalized at the C-12 position.…”