Germacrene B – a central intermediate in sesquiterpene biosynthesis

Houchao Xu and
Jeroen S. Dickschat

Review
Published 20 Feb 2023

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1. Graphical Abstract
2. Scheme 1: Possible cyclisation modes of FPP.
  
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3. Scheme 2: Structures of germacrene B (1), germacrene A (2) and hedycaryol (3).
  
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4. Scheme 3: The chemistry of germacrene B (1). A) Synthesis from germacrone (4), B) the four conformers of 1 es...
  
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5. Scheme 4: The chemistry of germacrene B (1). A) Cyclisation of 1 to 9 and 10 upon treatment with alumina, B) ...
  
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6. Scheme 5: Possible cyclisation reactions upon reprotonation of 1. A) Cyclisations to eudesmane sesquiterpenes...
  
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7. Scheme 6: Cyclisation modes for 1 to the eudesmane skeleton. A) The reprotonation of 1 at C-1 potentially lea...
  
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8. Scheme 7: The sesquiterpenes derived from cation I1. WMR = Wagner–Meerwein rearrangement.
  
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9. Scheme 8: The sesquiterpenes derived from cation I1. A) Pyrolysis of 23 to yield 9 and 10, B) deprotonation–r...
  
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10. Scheme 9: The sesquiterpenes derived from cation I1. A) Acid-catalysed conversion of 18 into 26, B) conversio...
  
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11. Scheme 10: The sesquiterpenes derived from cation I1. A) Formation of 20 by pyrolysis of 33, B) acid-catalysed...
  
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12. Scheme 11: The sesquiterpenes derived from cation I2. WMR = Wagner–Meerwein rearrangement.
  
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13. Scheme 12: The sesquiterpenes derived from cation I2. A) Acid catalysed conversion of 41 into 38, B) dehydrati...
  
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14. Scheme 13: The sesquiterpenes derived from cation I3. WMR = Wagner–Meerwein rearrangement.
  
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15. Scheme 14: Cyclisation modes for 1 to the guaiane skeleton. A) The reprotonation of 1 at C-4 potentially leads...
  
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16. Scheme 15: The sesquiterpenes derived from cations K1, K2 and K4. A) Mechanisms of formation for compounds 53–...
  
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17. Scheme 16: The sesquiterpenes derived from cations L1–L4. A) Mechanisms of formation for compounds 54, 56, 59 ...
  
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Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

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Synthesis of tryptophan-dehydrobutyrine diketopiperazine and biological activity of hangtaimycin and its co-metabolites

Houchao Xu,
Anne Wochele,
Minghe Luo,
Gregor Schnakenburg,
Yuhui Sun,
Heike Brötz-Oesterhelt and
Jeroen S. Dickschat

Letter
Published 07 Sep 2022

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1. Graphical Abstract
2. Scheme 1: Structures of hangtaimycin (1) and its co-metabolites.
  
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3. Scheme 2: First synthetic route towards TDD (4).
  
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4. Figure 1: HPLC analyses of (Z)-4 on a chiral stationary phase. A) Nearly racemic 4 from the first synthetic r...
  
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5. Scheme 3: Second synthetic route towards TDD ((Z)-4).
  
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6. Figure 2: X-ray structure of (rac)-4.
  
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7. Figure 3: Bioactivity testing with hangtaimycin (1). A) Growth retardation of model species B. subtilis 168 a...
  
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Beilstein J. Org. Chem. 2022, 18, 1159–1165, doi:10.3762/bjoc.18.120

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The enzyme mechanism of patchoulol synthase

Houchao Xu,
Bernd Goldfuss,
Gregor Schnakenburg and
Jeroen S. Dickschat

Full Research Paper
Published 03 Jan 2022

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1. Graphical Abstract
2. Figure 1: Initially assigned structures for patchoulol by Treibs (1) and by Büchi (2). Structures of patchoul...
  
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3. Scheme 1: Biosynthesis of patchoulol (part I). A) Cyclisation mechanism from FPP to 3 as suggested by Croteau...
  
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4. Scheme 2: Biosynthesis of patchoulol (part II). A) Cyclisation mechanism from FPP to 3 as suggested by Akhila...
  
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5. Scheme 3: Biosynthesis of patchoulol (part III). A) Cyclisation mechanism from FPP to 3 as suggested by Faral...
  
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6. Figure 2: ORTEP representation of patchoulol (3). Cu Kα, Flack parameter: −0.1(2); P2(true) = 1.000, P3(false...
  
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7. Scheme 4: Determination of the absolute configurations of compounds 3 and 12 through stereoselective labellin...
  
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8. Scheme 5: Labelling experiments on the biosynthesis of patchoulol (3, part 1). Black dots indicate ¹³C-labell...
  
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9. Scheme 6: Labelling experiments on the biosynthesis of patchoulol (3, part 2). Black dots indicate ¹³C-labell...
  
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10. Figure 3: Energy profile from DFT calculations (Gibbs energies at 298 K, mPW1PW91/6-311 + G(d,p)//B97D3/6-31G...
  
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11. Figure 4: Structure elucidation of (2S,3S,7S,10R)-guaia-1,11-dien-10-ol (17) and structure of its known stere...
  
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