Base-Induced Rearrangement of Perhydronaphthalene-1,4-diol Monosulfonate Esters to 11-Oxatricyclo[5.3.1.0^2,6]undecanes. Total Synthesis of Furanether B

Abstract

It is observed that mesylate 1 on exposure to Li(Ot-Bu)(3)AlH in refluxing toluene rearranges selectively to the 11-oxatricyclo[5.3.1.0(2,6)]undecane derivative 3. A similar rearrangement, leading to a bridged tricyclic ether (14 --> 5), has been used as the key to the total synthesis of furanether B (4), a naturally occurring lactarane sesquiterpene, with the readily available ketone 8 as the starting material. Completion of the synthesis of the natural product is accomplished by an annulation method based on a Pummerer-induced cyclization reaction.

Reactivity versus Stability of Oxiranes under Palladium‐Catalyzed Reductive Conditions

“…Surprisingly, no reaction at all was observed from the treatment of the epoxy ketone shown in Equation (55) under Torii's [105] or Dragovich's [29] experimental conditions. [118] www.eurjoc.org…”

Natural sesquiterpenoids

“…196 The total synthesis of the lactarane sesquiterpene furanether B has been described. 197 Isodehydroilludin M, an oxidation product of the cytotoxic sesquiterpene illudin M, has been synthesized, 198 whilst several illudin S derivatives, labelled with tritium, have been prepared from the fermentation of the fungus Omphalotus illudens in the presence of [ 3 H]-sodium acetate. 199 The africanane derivative epi-swartzianin A 148 has been isolated from the liverwort Pellia epiphylla.…”

Total Synthesis of (±)-Furanether A

“…In addition, both Wijnberg and Tanino groups prepared the tricyclic key skeleton from the hydroazulene type skeletons through an intramolecular cyclization (Scheme ). , In contrast with the reports for the synthesis of furanether B, a synthetic strategy toward furanether A is very limited. To the best of our knowledge, no total synthesis of furanether A has been achieved, which might be attributed to the special bowl-shaped molecular skeleton.…”

“…Following the discovery and bioactivity studies of 1–3 , the development of efficient synthetic approaches toward the synthesis of these molecules or their special tetracyclic skeleton has also attracted the attention of synthetic chemists. As for the construction of the key skeleton of furanether B, several elegant strategies have been developed. − In 1989, Price and Schore constructed the key skeleton with a cis -fused cyclopentane moiety via Pauson–Khand type cycloaddition from an oxa-bridged precursor and an alkyne cobalt complex, and the strategy could afford the cyclization products with an exclusive exo configuration, which might be attributed to the steric hindrance of cobalt adducts. Molander and Carey employed an efficient tandem [3+4] cyclization between the oxocarbenium ion intermediate and bis­(trimethylsilyl)­enolether as the key step to finish the synthesis of furanether B.…”