Total Synthesis of the <i>Galbulimima</i> Alkaloid (−)‐GB17

Larson, Reed T.; Clift, Michael D.; Thomson, Regan J.

doi:10.1002/anie.201108227

Cited by 24 publications

(17 citation statements)

References 48 publications

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“…Most of the new members isolated could be regarded as metabolites or precursors of the known alkaloids. Nevertheless, the isolation and identification of these new family members have shed more light on the biosynthesis route of the Galbulimima alkaloids, which has been proved by the semisynthesis of GB22 (15) and the interconversions of GB14 ( 14), GB25 (16), and GB24 (19). The present work has also found some missing links in the biosynthetic sequences.…”

Section: ■ Conclusionmentioning

confidence: 99%

“…Because of their fascinating structural features as well as potential pharmacological applications, the Galbulimima alkaloids have attracted considerable attention from the synthetic community. The total syntheses of eight representative members, that is, himbacine, himbeline, himandravine, himandrine, GB13, himgaline, , GB16, and GB17, , have been completed by creative synthetic endeavor. , Meanwhile, the biogenesis of the Galbulimima alkaloids has been discussed extensively within these synthetic works. , …”

Section: Introductionmentioning

confidence: 99%

“…17,14b Our continuing efforts to explore the chemical constituents from G. belgraveana and G. baccata have led to some interesting findings. Herein, we report the isolation and structure elucidation of seven new alkaloids, namely, GB14 (14), GB22 (15), GB25 (16), GB21 (17), GB23 (18), GB24 (19), and GB26 (20). Compounds 14−16 (Figure 2) were obtained from the extracts of the bark, whereas the remaining four alkaloids 17−20 (Figure 3) were isolated from the methanol extracts of fresh leaves of G. baccata.…”

Section: ■ Introductionmentioning

confidence: 99%

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Structures of New Alkaloids from Rain Forest Trees Galbulimima belgraveana and Galbulimima baccata in Papua New Guinea, Indonesia, and Northern Australia

et al. 2018

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Following on our 60-year research on the chemical constituents of the rain forest trees Galbulimima belgraveana and Galbulimima baccata , we report the isolation of seven new alkaloids: GB14 ( 14 ), GB22 ( 15 ), GB25 ( 16 ), GB21 ( 17 ), GB23 ( 18 ), GB24 ( 19 ), and GB26 ( 20 ). Their structures were elucidated by a combination of spectroscopic analyses and single-crystal X-ray crystallography, as well as structure degradation and interconversion. The newly isolated alkaloids are precursors or derivatives of the known family members from our early studies and could be intermediates in the biosynthesis of the Galbulimima alkaloids. Therefore, the present study has expanded the range of structures in this family of alkaloids and provided some missing links in the biosynthetic sequences.

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Section: ■ Conclusionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Structures of New Alkaloids from Rain Forest Trees Galbulimima belgraveana and Galbulimima baccata in Papua New Guinea, Indonesia, and Northern Australia

et al. 2018

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“…1 H and 13 C NMR spectral data of GB17 ( 8 ) prepared in this manner matched those of an authentic sample, as well as literature reports. 7,28 …”

Section: Resultsmentioning

confidence: 99%

“…27 Of the Class IV alkaloids, GB16 ( 7 ) was synthesized by Ma and co-workers in 2010, 26 while our own group completed the synthesis of GB17 ( 8 ) in 2011. 28 …”

Section: Introductionmentioning

confidence: 99%

Total Synthesis of the Galbulimima Alkaloids Himandravine and GB17 Using Biomimetic Diels–Alder Reactions of Double Diene Precursors

et al. 2015

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The enantioselective total syntheses of himandravine and GB17 were completed through a common biomimetic strategy involving Diels–Alder reactions of unusual double diene containing linear precursors. The double diene precursors, containing or lacking a C12 substituent as required to produce GB17 or himandravine, respectively, were found to undergo Diels–Alder reactions to afford mixtures of regioisomeric cycloadducts that map onto the alternative carbocyclic frameworks of both himandravine and GB17. Computational investigations revealed that these Diels–Alder reactions proceed via transition state structures of similar energy that have a high degree of bispericyclic character and that the low levels of regioselectivity observed in the reactions are a consequence of competing orbital interaction and distortion energies. The combined experimental and computational results provide valuable insights into the biosynthesis of the Galbulimima alkaloids.

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The Catalytic, Enantioselective Michael Reaction

et al. 2016

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The catalytic enantioselective Michael reaction is the conjugate addition of a resonance‐stabilized carbanion to an electron‐poor olefin (an αβ‐unsaturated carbonyl compound or a related derivative) mediated by substoichiometric amounts of a chiral catalyst that enables stereocontrol in the newly generated stereocenter(s). This reaction allows the direct enantioselective construction of substituted 1,5‐dicarbonyl compounds or related architectures through the appropriate selection of the enolizable carbonyl compound employed as pronucleophile and the Michael acceptor. A variety of catalyst architectures have been described that make it possible to carry out this reaction with superior levels of chemical efficiency and high enantio‐ and stereocontrol, and also under conditions that tolerate a wide variety of functional groups. Both transition metal catalysis and organocatalysis have been employed as methodological approaches for carrying out this reaction in an enantioselective manner. This chapter describes different catalytic systems and methods developed for achieving enantioselective Michael reactions through the end of 2012, including a detailed mechanistic explanation of the different generic modes of substrate activation operating with each type of catalyst and their associated stereochemical aspects. The intention is to provide researchers interested in applying this methodology to their own synthetic strategies with a suitable starting point for identifying an efficient synthetic approach. In addition, the preparation of selected catalysts that are excellent for a particular pairing of substrates in this reaction, together with practical experimental protocols are described and some examples in which these methodologies have been applied to total synthesis have been included. This chapter is limited exclusively to those examples in which the final Michael addition product is obtained after protonation of the conjugate addition intermediate and therefore, tandem, domino, or cascade processes initiated by Michael reactions lie outside the scope of this work. Supplemental references are provided for articles published after the 2012 cut‐off date through the first half of 2015.

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Total Synthesis of the Galbulimima Alkaloid (−)‐GB17

Cited by 24 publications

References 48 publications

Structures of New Alkaloids from Rain Forest Trees Galbulimima belgraveana and Galbulimima baccata in Papua New Guinea, Indonesia, and Northern Australia

Structures of New Alkaloids from Rain Forest Trees Galbulimima belgraveana and Galbulimima baccata in Papua New Guinea, Indonesia, and Northern Australia

Total Synthesis of the Galbulimima Alkaloids Himandravine and GB17 Using Biomimetic Diels–Alder Reactions of Double Diene Precursors

The Catalytic, Enantioselective Michael Reaction

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