Synthesis of (±)-eriobrucinol and regioisomeric monoterpenoid coumarins, using intramolecular cycloadditions

Crombie, Leslie; Redshaw, Sally; Slack, D. A.; Whiting, Donald A.

doi:10.1039/p19830001411

Cited by 12 publications

(3 citation statements)

References 9 publications

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“…29 (diastereomeric mixture in nearly 1:1 ratio): 1 H NMR (200 MHz, CDCl 3 ) δ 0.98 (s, 3H), 1.00-1.35 (m, 4H), 1.44 (d, J ) 2 Hz, 3H), 1.50 (s, 3H), 1.59 (s, 3H), 1.63 (s, 3H), 1.60-1.80 (m, 2H), 1.67 (s, 3H), 2.00-2.20 (m, 2H), 4.80-4.95 (m, 1H), 5.05-5.20 (m, 1H), 5.24 (d, J ) 10 Hz, 1H), 5.44 (dd, J ) 10, 2 Hz, 1H), 6.55 (d, J ) 10 Hz, 1H), 6.74 (d, J ) 10 Hz, 1H), 7.30-7.52 (m, 5H), 12.71 (s, 1H); 13 C NMR (50 MHz, CDCl 3 ) δ 17.5, 22.4, 22.6, 25.5/25.6, 25.9, 26.9, 27.0, 40.8, 41. 5…”

Section: -Bromo-15-dimethoxy-3-methylbenzene (14)mentioning

confidence: 99%

“…Several structurally complex compounds with a hexahydrooxacyclobutaindan moiety have been isolated as bioactive natural products and are depicted in Figure . − All of these oxacyclobutaindans bear the free phenolic group/groups, and one can easily make out that nature might be designing them by using the condensation reactions of phenolic compounds with citral and/or farnesal via [2 + 2] cycloaddition reactions. The natural products with oxabicyclononane units have been shown in Figure , , and one gets a feeling that Nature might be making them via intramolecular cyclization of phenolic groups with the correctly attached limonene moiety .…”

Section: Introductionmentioning

confidence: 99%

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A Facile Phenol-Driven Intramolecular Diastereoselective Thermal/Base-Catalyzed Dipolar [2 + 2] Annulation Reactions: An Easy Access to Complex Bioactive Natural and Unnatural Benzopyran Congeners

2007

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The complex bioactive natural and unnatural benzopyran congeners have been synthesized using one-/two-step approaches in very good yields from the reactions of two different dihydroxyphthalides, natural resorcyclic acid derivative, and trihydroxybenzophenone with citral and/or farnesal, via the phenol-driven intramolecular diastereoselective thermal/base-catalyzed dipolar [2+2] cycloaddition reactions and three different thermal intramolecular cyclization reactions. The effects of the nature and the position of phenolic groups in the starting materials on the course of these cycloaddition reactions have also been described. Depending upon the absence or presence of intramolecular hydrogen bonding of the phenolic group with the carbonyl moiety in the starting materials, these phenol-driven intramolecular thermal/base-catalyzed dipolar [2+2] cycloaddition reactions either furnished the kinetically controlled products or directly formed the thermodynamically controlled rearranged products, respectively.

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Section: -Bromo-15-dimethoxy-3-methylbenzene (14)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Facile Phenol-Driven Intramolecular Diastereoselective Thermal/Base-Catalyzed Dipolar [2 + 2] Annulation Reactions: An Easy Access to Complex Bioactive Natural and Unnatural Benzopyran Congeners

2007

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“…Despite extensive work in this area, Crombie was unable to investigate the biomimetic conversion of 8 into eriobrucinol because of his failure to synthesize 8 . However, Crombie did achieve biomimetic, photochemical syntheses of the isomeric natural products, iso-eriobrucinols A and B (vide infra), and he also confirmed the structure of eriobrucinol ( 6 ) via a less direct total synthesis …”

Section: Results and Discussionmentioning

confidence: 99%

Biomimetic Synthetic Studies on the Bruceol Family of Meroterpenoid Natural Products

2019

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A biomimetic approach to total synthesis can offer several benefits, including the development of cascade reactions for the rapid generation of molecular complexity, and guidance in the structure revision of old natural products and the anticipation of new ones. Herein, we describe how a biomimetic synthesis of bruceol, a pentacyclic meroterpenoid, led to the anticipation, isolation, and synthesis of isobruceol. The key step in the synthesis of both bruceol and isobruceol was an intramolecular hetero-Diels−Alder reaction of an oquinone methide that was formed by dearomatization of an electron-rich chromene. The synthesis of an elusive biosynthetic intermediate also allowed a concise synthesis of eriobrucinol via a photochemical [2 + 2] cycloaddition. Furthermore, some speculation on the biosynthesis of prenylated bruceol derivatives inspired the development of a Claisen/Cope/Diels−Alder cascade reaction. We also report the generation of halogenated bruceol derivatives and the synthesis of several protobruceol natural products using singlet oxygen ene reactions. Article pubs.acs.org/joc

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1987

Chemistry of Heterocyclic Compounds: A Series of Monographs

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Synthesis of (±)-eriobrucinol and regioisomeric monoterpenoid coumarins, using intramolecular cycloadditions

Abstract: Unambiguous syntheses of the three regioisomers (8), (13), and (16), of the eriobrucinol structure, are reported. The (k) -cyclol ( 8) is spectrally identical with natural (-) -eriobrucinol from Eriostemon brucei, thus confirming Jefferies and Worth's structural proposal by synthesis.

Cited by 12 publications

References 9 publications

A Facile Phenol-Driven Intramolecular Diastereoselective Thermal/Base-Catalyzed Dipolar [2 + 2] Annulation Reactions: An Easy Access to Complex Bioactive Natural and Unnatural Benzopyran Congeners

A Facile Phenol-Driven Intramolecular Diastereoselective Thermal/Base-Catalyzed Dipolar [2 + 2] Annulation Reactions: An Easy Access to Complex Bioactive Natural and Unnatural Benzopyran Congeners

Biomimetic Synthetic Studies on the Bruceol Family of Meroterpenoid Natural Products

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