Natural Products Containing the Oxetane and Related Moieties

May 30, 2019 - Analysis of published NMR data for natural products containing the oxetane moiety, with the help of a recently developed parametric/DFT...
0 downloads 0 Views 5MB Size
Subscriber access provided by Bethel University

Featured Article

Natural Products Containing the Oxetane and Related Moieties Present Additional Challenge for Structure Elucidation: a DU8+ Computational Case Study Andrei G. Kutateladze, Tina Holt, and D. Sai Reddy J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.9b01005 • Publication Date (Web): 30 May 2019 Downloaded from http://pubs.acs.org on May 31, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Organic Chemistry

Natural Products Containing the Oxetane and Related Moieties Present Additional Challenge for Structure Elucidation: a DU8+ Computational Case Study.

INTRODUCTION 1



6

RESULTS AND DISCUSSION

2

3 4

7

5

8

9

12

13 15

10 11 14

16

17

18

19



20

21 22

ACS Paragon Plus Environment

The Journal of Organic Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 13

28

29

23 24

 

25

26

27

2 Environment ACS Paragon Plus

Page 3 of 13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Organic Chemistry

30

31

32

33

34 35 36

37

38

39



40

41



3 Environment ACS Paragon Plus

The Journal of Organic Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 4 of 13

42

43

44

4 Environment ACS Paragon Plus

45

Page 5 of 13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Organic Chemistry

 

50

46

47

48

49

51



52



5 Environment ACS Paragon Plus

The Journal of Organic Chemistry 

53

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 13

54

55

56

59

57





58



60





6 Environment ACS Paragon Plus

Page 7 of 13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Organic Chemistry

61

65

62

66

67

63

68

69

70 64



7 Environment ACS Paragon Plus

The Journal of Organic Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 13

71

72

73

74

75



8 Environment ACS Paragon Plus

Page 9 of 13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Organic Chemistry



83

76



77

78 79

CONCLUSIONS

ASSOCIATED CONTENT

AUTHOR INFORMATION Corresponding Author

Notes

80

ACKNOWLEDGMENT

TOC GRAPHICS: 

81

9 Environment ACS Paragon Plus

The Journal of Organic Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 10 of 13

REFERENCES

(1) Search of the Dictionary of Natural Products (http://dnp.chemnetbase.com) revealed that the oxetane-containing natural products constitute less than 0.5% of NPs in the database. (2) (a) for review see Lodewyk, M. W.; Siebert, M. R.; Tantillo, D. J. Computational prediction of 1H and 13C chemical shifts: a useful tool for natural product, mechanistic, and synthetic organic chemistry. Chem. Rev. 2012, 112, 1839. (b) see also Tantillo's compilation of various computational approaches at http://cheshirenmr. info (c) Smith, S. G.; Goodman, J. M. Assigning stereochemistry to single diastereoisomers by GIAO NMR calculation: the DP4 probability. J. Am. Chem. Soc. 2010, 132, 12946. (d) Grimblat, N.; Zanardi, M. M.; Sarotti, A. M. Beyond DP4: an improved probability for the stereochemical assignment of isomeric compounds using quantum chemical calculations of NMR shifts. J. Org. Chem. 2015, 80, 12526. (e) Elyashberg, M. E.; Williams, A. J. Structural revisions of natural products by computer-assisted structure elucidation (CASE) systems. Nat. Prod. Rep. 2010, 27, 1296. (f) Elyashberg, M. E.; Williams, A. J. Computer-Based Structure Elucidation from Spectral Data. The Art of Solving Problems; Springer: Heidelberg, 2015. (g) Buevich, A. V.; Elyashberg, M. E. Synergistic combination of CASE algorithms and DFT chemical shift predictions: a powerful approach for structure elucidation, verification, and revision. J. Nat. Prod. 2016, 79, 3105. (h) Bally, T.; Rablen, P. R. Quantum-chemical simulation of 1H NMR spectra. 2.† comparison of DFT-based procedures for computing proton–proton coupling constants in organic molecules. J. Org. Chem. 2011, 76, 4818. (3) hexacyclinol: (a) original report: Schlegel, B.; Härtl, A.; Dahse, H. -M.; Gollmick, F. A.; Gräfe, U.; Dörfelt, H.; Kappes, B. Hexacyclinol, a new antiproliferative metabolite of Panus rudis HKI 0254. J. Antibiotics, 2002, 55, 814. (b) computational revision: Rychnovsky, S. D. Predicting NMR spectra by computational methods: Structure revision of hexacyclinol. Org. Lett. 2006, 8, 2895. (c) synthetic validation of the revised structure: Porco, J. A. Jr.; Su, S.; Lei, X.; Bardhan, S.; Rychnovsky, S. D. Total synthesis and structure assignment of (+)‐Hexacyclinol. Angew. Chem., Int. Ed. 2006, 45, 5790. (4) (a) Kutateladze, A. G.; Mukhina, O. A. Relativistic force field: parametric computations of proton–proton coupling constants in 1H NMR spectra. J. Org. Chem. 2014, 79, 8397. (b) Kutateladze, A. G.; Mukhina, O. A. Minimalist relativistic force field: prediction of proton–proton coupling constants in 1H NMR spectra is perfected with NBO hybridization parameters. J. Org. Chem. 2015, 80, 5218. (c) Kutateladze, A. G.; Mukhina, O. A. Relativistic force field: parametrization of 13C–1H nuclear spin– spin coupling constants. J. Org. Chem. 2015, 80, 10838. (5) for the full description of the components of DU8+ method see Kutateladze, A. G.; Reddy, D. S. High-throughput in silico structure validation and revision of halogenated natural products is enabled by parametric corrections to DFT-computed 13C NMR chemical shifts and spin–spin coupling constants. J. Org. Chem. 2017, 82, 3368. (6) (a) Kutateladze A. G.; Krenske E. H.; Williams, C. M. Reassignments and corroborations of oxo-bridged natural products directed by OSE and DU8+ NMR computation. Angew.Chem. 2019, accepted (b) Kutateladze, A. G.; Kuznetsov, D. M.; Beloglazkina, A. A.; Holt, T. J. Addressing the challenges of structure elucidation in natural products possessing the oxirane moiety. J. Org. Chem., 2018, 83, 8341. (c) Kutateladze, A. G.; Kuznetsov, D.

M. Triquinanes and related sesquiterpenes revisited computationally: structure corrections of Hirsutanols B and D, Hirsutenol E, Cucumin B, Antrodins C–E, Chondroterpenes A and H, Chondrosterins C and E, Dichrocephone A, and Pethybrene. J. Org. Chem., 2017, 82, 10795. (7) Ortega, A.; Maldonado, E. Pseudoguaianolides from parthenium fruticosum. Phytochemistry, 1986, 25, 699. (8) Kurata, K.; Suzuki, T.; Suzuki, M.; Kurosawa, E.; Furusaki, A.; Matsumoto, T. Laureacetal-D and -E, two new secochamigrane derivatives from the red alga Laurencia nipponica Yamada. Chem. Lett. 1983, 557. (9) Yu, X.-Q.; Jiang, C.-S.; Zhang, Y.; Sun, P.; Kurtan, T.; Mandi, A.; Li, X.-L.; Yao, L.-G.; Liu, A.-H.; Wang, B.; Guo, Y.W.; Mao, S.-C. Compositacins A–K: bioactive chamigrane-type halosesquiterpenoids from the red alga Laurencia composita Yamada. Phytochem. 2017, 136, 81. (10) original discovery of dictyoxetane: (a) Pullaiah, K. C.; Surapaneni, R. K.; Rao, C. B.; Albizati, K. F.; Sullivan, B. W.; Faulkner, D. J.; Cun-heng, H.; Clardy, J. Dictyoxetane, a novel diterpene from the brown alga Dictyota dichotoma from the Indian Ocean. J. Org. Chem.1985, 50, 3665. (b) Rao, C. B.; Pullaiah, K. C.; Surapaneni, R. K.; Sullivan, B. W.; Albizati, K. F.; Faulkner, D. J.; Cun-heng, H.; Clardy, J. The diterpenes of Dictyota dichotoma from the Indian Ocean. J. Org. Chem. 1986, 51, 2736. (11) 13C NMR chemical shifts for dyctyoxetane are taken from the total synthesis paper: Hugelshofer, C. L.; Magauer, T. A. A Bioinspired cyclization sequence enables the asymmetric total synthesis of dictyoxetane. J. Am. Chem. Soc. 2016, 138, 6420. This paper also gives a nice introduction to naturally occurring oxetanes (or lack thereof). (12) Tian, X.; Li, L.; Hu, Y.; Zhang, H.; Liu, Y.; Chen, H.; Ding, G.; Zou, Z. Dichrocephones A and B, two cytotoxic sesquiterpenoids with the unique [3.3.3] propellane nucleus skeleton from dichrocephala benthamii. RSC Adv. 2013, 3, 7880. (13) Li, C.; Lee, D.; Graf, T. N.; Phifer, S. S.; Nakanishi, Y.; Burgess, J. P.; Riswan, S.; Setyowati, F. M.; Saribi, A. M.; Soejarto, D. D.; Farnsworth, N. R.; Falkinham III, J. O.; Kroll, D. J.; Kinghorn, A. D.; Wani, M. C.; Oberlies, N. H. A Hexacyclic ent-trachylobane diterpenoid possessing an oxetane ring from mitrephora glabra. Org. Lett. 2005, 7, 5709. (14) Richter, M. J. R.; Schneider, M.; Brandstätter, M.; Krautwald, S.; Carreira, E. M. Total synthesis of (−)-Mitrephorone A. J. Am. Chem. Soc. 2018, 140, 16704. (15) Centko, R. M.; Ramon-Garcia, S.; Taylor, T.; Patrick, B. O.; Thompson, C. J.; Miao, V. P.; Andersen, R. J. Ramariolides A–D, antimycobacterial butenolides isolated from the mushroom ramaria cystidiophora. J. Nat. Prod. 2012, 75, 2178. (16) Vander Velde, D. G.; Georg, G. I.; Gollapudi, S. R.; Jampani, H. B.; Liang, X.-Z.; Mitscher, L. A.; Ye, Q.-M. Wallifoliol, a Taxol congener with a novel carbon skeleton, from Himalayan Taxus Wallichiana. J. Nat. Prod. 1994, 57, 862. (17) Kim, C. S.; Oh, J.; Subedi, L.; Kim, S. Y.; Choi, S. U.; Lee, K. R. Structural characterization of terpenoids from abies holophylla using computational and statistical methods and their biological activities. J. Nat. Prod. 2018, 81, 1795. (18) Ren, F.; Chen, S.; Zhang, Y.; Zhu, S.; Xiao, J.; Liu, X.; Su, R.; Che, Y. Hawaiienols A–D, Highly oxygenated p-terphenyls from an insect-associated fungus, paraconiothyrium hawaiiense. J. Nat Prod. 2018, 81, 1752.

10 Environment ACS Paragon Plus

Page 11 of 13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Organic Chemistry (35) Li, D.; Chen, Y.; Pan, Q.; Tao, M.; Zhang, W. A new eudesmane sesquiterpene from nigrospora oryzae, an endophytic fungus of aquilaria sinensis. Rec. Nat. Prod. 2014, 8, 330. (36) (a) Li, R.-J.; Zhu, R.-X.; Li, Y.-Y.; Zhou, J.-C.; Zhang, J.Z.; Wang, S.; Ye, J.-P.; Wang, Y.-H.; Morris-Natschke, S. L.; Lee, K.-H.; Lou, H.-X. Secondary metabolites from the Chinese liverwort cephaloziella kiaeri. J. Nat. Prod. 2013, 76, 1700. (b) Another complex clerodane diterpenoid, cephaloziellin A (not shown), was assigned correctly, as evidenced by a good match, rmsd(δC) = 1.24 ppm, see SI. (37) Jianmei, H.; Jialin, W.; Chunshu, Y. Sesquiterpene lactones from the pericarp of illicium dunnianum. Phytochem. 1997, 46, 777. (38) Yokoyama, R.; Huang, J.-M.; Hosoda, A.; Kino, K.; Yang, C.-S.; Fukuyama, Y. Seco-prezizaane-type sesquiterpenes and an abietane-type diterpene from illicium minwanense. J. Nat. Prod. 2003, 66, 799. (39) Liu, J.-M.; Zhang, D.-W.; Du, W.-Y.; Zhang, M.; Zhao, J.L.; Chen, R.-D.; Xie, K.-B.; Dai, J.-G. Four new monoterpenoids from an endophytic fungus periconia sp. F-31. J. Asian Nat. Prod. Res. 2017, 19, 541. (40) Ni, L.; Ma, J.; Li, C.-J.; Li, L.; Guo, J.-M.; Yuan, S.-P.; Hou, Q.; Guo, Y.; Zhang, D.-M. Novel rearranged and highly oxygenated abietane diterpenoids from the leaves of tripterygium wilfordii. Tetrahedron Lett. 2015, 56, 1239. (41) Lin, T.; Wang, G.; Shan, W.; Zeng, D.; Ding, R.; Jiang, X.; Zhu, D.; Liu, X.; Yang, S.; Chen, H. Myrotheciumones: Bicyclic cytotoxic lactones isolated from an endophytic fungus of ajuga decumbens. Bioorg. Med. Chem. Lett. 2014, 24, 2504. (42) Hilmi, F.; Sticher, O.; Heilmann, J. New cytotoxic 6,7-cis and 6,7-trans configured guaianolides from warionia saharae. J. Nat. Prod. 2002, 65, 523. (43) Swern, D.; Clements, A. H.; Luong, T. M. Nuclear magnetic resonance spectra of organic peroxides. Analytical Chem. 1969, 41, 412. (44) Adio, A. M.; Paul, C.; König, W. A.; Muhle, H. Volatile constituents in the liverwort tritomaria polita. Phytochem.2003, 64, 637. (45) Liang, Y.; Li, X.-M.; Cui, C.-M.; Li, C.-S.; Sun, H.; Wang, B.-G. Sesquiterpene and acetogenin derivatives from the marine red alga Laurencia okamurai. Mar. Drugs 2012, 10, 2817. (46) Aitken, R. A.; Karodia, N.; McCarron, H. B.; Rouxel, C.; Sahabo, N.; Slawin, A. M. Z. Synthesis, structure and pyrolysis of stabilised phosphonium ylides containing saturated oxygen heterocycles. Org. Biomol. Chem.2016, 14, 1794 and references therein. (47) (a) Friedrich, L. E.; Lam, P. Y.-S. Syntheses and reactions of 3-phenyloxete and the parent unsubstituted oxete. J. Org. Chem. 1981, 46, 306. (b) Aikawa, K.; Hioki, Y.; Shimizu, N.; Mikami, K. Catalytic asymmetric synthesis of stable oxetenes via Lewis acidpromoted [2 + 2] cycloaddition. J. Am. Chem. Soc. 2011, 133, 20092. (48) Alcaide, B.; Almendros, P.; Martinez del Campo, T.; Fernandez, I. Fascinating reactivity in gold catalysis: synthesis of oxetenes through rare 4-exo-dig allene cyclization and infrequent βhydride elimination. Chem. Comm. 2011, 47, 9054. (49) Chen, J.; Bai, X.; Hua, Y.; Zhang, H.; Wang, H. Fusariumins C and D, two novel antimicrobial agents from fusarium oxysporum ZZP-R1 symbiotic on rumex madaio Makino. Fitoterapia, 2019, 134, asap https://doi.org/10.1016/j.fitote.2019.01.016 (50) (a) Gu, Z.; Liang, H.; Chen, H.; Xu, Y.; Zhang, W. Isolation and identification of cheliensisamine from the bark of goniothalamus cheliensis. Chinese Trad. Herb. Drugs 2000, 31, 885. (b) Wang, Q.-Z.; He, M.-F.; Liang, J.-Y. Advances in studies on chemical constituents and physiological activity of goniothalamus. Chinese Trad. Herb. Drugs 2003, 34, 277.

(19) Huang, J.-M.; Yokoyama, R.; Yang, C.-S.; Fukuyama, Y. Merrilactone A, a novel neurotrophic sesquiterpene dilactone from illicium merrillianum. Tetrahedron Lett. 2000, 41, 6111. (20) Liu, D.-Z.; Wang, F.; Liao, T.-G.; Tang, J.-G.; Steglich, W.; Zhu, H.-J.; Liu, J.-K. Vibralactone:  A lipase inhibitor with an unusual fused β-lactone produced by cultures of the basidiomycete boreostereum vibrans. Org. Lett. 2006, 8, 5749. (21) Zou, J.; Pan, L.; Li, Q.; Zhao, J.; Pu, J.; Yao, P.; Gong, N.; Lu, Y.; Kondratyuk, T. P.; Pezzuto, J. M.; Fong, H. H. S.; Zhang, H.; Sun, H. Rubesanolides A and B: diterpenoids from isodon rubescens. Org. Lett. 2011, 13, 1406. (22) Nakamura, T.; Okuyama, E.; Yamazaki, M. Neurotropic components from star anise: illicium verum HOOK. fil. Chem. Pharm. Bull. 1996, 44, 1908. (23) Kirschberg, T.; Mattay, J. Photoinduced electron transfer reactions of α-cyclopropyl- and α-epoxy ketones. Tandem fragmentation−cyclization to bi-, tri-, and spirocyclic ketones. J. Org. Chem. 1996, 61, 8885. (24) here and later we will retain the numbering of the products as reported in the original papers, to avoid confusion. (25) (a) Jones, G.; Schwartz, S. B.; Marton, M. T. Regiospecific thermal cleavage of some oxetan photoadducts: carbonyl–olefin metathesis in sequential photochemical and thermal steps. J. Chem. Soc., Chem. Commun. 1973, 11, 374. (b) Jones, G.; Acquadro, M. A.; Carmody, M. A. Long-chain enals via carbonyl–olefin metathesis. An application in pheromone synthesis. J. Chem. Soc., Chem. Commun. 1975, 6, 206. (c) Perez-Ruiz, R.; Miranda, M. A.; Alle, R.; Meerholz, K.; Griesbeck, A. An efficient carbonyl-alkene metathesis of bicyclic oxetanes: photoinduced electron transfer reduction of the Paternò–Büchi adducts from 2,3-dihydrofuran and aromatic aldehydes. Photochem. Photobiol. Sci. 2006, 5, 51. (26) (a) Valiulin, R. A.; Kutateladze, A. G. Harvesting the strain installed by a Paternò−Büchi step in a synthetically useful way: high-yielding photoprotolytic oxametathesis in polycyclic systems. Org. Lett., 2009, 11, 3886. (b) Valiulin, R. A.; Arisco, T. M., Kutateladze, A. G. Double-tandem [4π+2π]·[2π+2π]·[4π+2π]·[2π+2π] synthetic sequence with photoprotolytic oxametathesis and photoepoxidation in the chromone series. J. Org. Chem., 2011, 76, 1319 (27) It is possible but unlikely that the revised minor product is derived from oxametathesis of 47. This would involve fragmentation into cyclobutene and formaldehyde followed by bimolecular Paterno-Buchi reaction of these pieces, which is highly unlikely. (28) Blanco-Ania, D.; Gawade, S. A.; Zwinkels, L. J. L.; Maartense, L.; Bolster, M. G.; Benningshof, J. C. J.; Rutjes, P. J. T. Rapid and scalable access into strained scaffolds through continuous flow photochemistry. Org. Proc. Res. Dev. 2016, 20, 409. (29) Elliott, L. D.; Booker-Milburn, K. I. Photochemically Produced Aminocyclobutanes as Masked Dienes in Thermal Electrocyclic Cascade Reactions. Org. Lett. 2019, 21, 1463. (30) Tian, J.; Zhao, Q.-S.; Zhang, H.-J.; Lin, Z.-W.; Sun, H.-D. New cleroindicins from clerodendrum indicum. J. Nat. Prod. 1997, 60, 766. (31) Ogasawara, K. Preparation and exploitation of versatile cyclohexanoid chiral building blocks. J. Synth. Org. Chem. Jpn. 1999, 57, 957. (32) (a) a much more prominent example for these rare cases is Rychnovsky's work on hexacyclinol, see ref 3. (b) an additional curious fact is that SciFinder identifies seven suppliers of cleroindicin A with the original oxetane structure. (33) Shiu, L-L.; Chen, W-C.; Kuo, Y-H. Five new cis-himachalane-type sesquiterpenes from the heartwood of juniperus chinensis var. tsukusiensis. Chem. Pharm. Bull. 1999, 47, 557. (34) Li, N.; Chen, J.-J.; Zhou, J. Capitulatin B, a new eudesmane derivative from curculigo capitulata, and revised assignment of 13C 11 NMR data of 6α,15α-epoxy-1β,4β-dihydroxyeudesmane. J. Asian ACS Paragon Plus Environment Nat. Prod. Res. 2005, 7, 279.

The Journal of Organic Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 13

(72) Xie, Y.-G.; Wu, G.-J.; Cheng, T.-F.; Zhu, S.-L.; Yan, S.-K.; Jin, H.-Z.; Zhang, W.-D. Vielopsides A-E, five new guaiane-type sesquiterpenoid dimers from Xylopia vielana. Fitoterapia, 2018 130, 43 (there is a typo in the structures of vielopsides A-C: OH, not Me should be in the position 8). (73) examples of β-lactols: (a) Vittimberga, B. M.; Herz, M. The alumina-catalyzed condensation of 9-carbazolylacetaldehyde. J. Org. Chem.1970, 35, 3974. (b) Pistara, V.; Corsaro, A.; Rescifina, A.; Catelani, G.; D'Andrea, F.; Guazzelli, L. Prevalence of oxetanose forms in the tautomeric equilibrium of β-hydroxy-1,5dicarbonyl monosaccharides. J. Org. Chem. 2013, 78, 9444. (c) Hanessian, S.; Girard, C. Double stereodifferentiating DreidingSchmidt reactions. Synlett. 1994, 865. (d) Soengas, R. G. Indium-mediated Reformatsky reaction on lactones: preparation of 2-deoxy-2,2′-dimethyl-3-ulosonic acids. Tetrahedron Lett. 2010, 51, 105. (74) Jimenez, O.; Bosch, M.P.; Guerrero, A. A new, mild, and efficient synthesis of 2,2-difluoro-3-hydroxyacids through a selective haloform reaction. J. Org. Chem. 2005, 70, 10883. (75) Zhang, Q.; Liu, X.-T.; Liang, J.-Y.; Min, Z.-D. Chemical Constituents from the Stems of caesalpinia decapetala. Chinese J. Nat. Med. 2008, 6, 168. (76) Cheng, M.-J.; Lo, W.-L.; Huang, L.-Y.; Wang, C.-J.; Chen, C.-Y. Isolation of a 2-oxetanone from the fruits of synsepalum dulcificum. Nat. Prod. Res. 2010, 24, 1850. (77) Malic acid is poorly soluble in chloroform. It is conceivable that the low intensity peak from one of the carboxylates was not detected in the original work on ficumone. (78) Li, H.; Li, L.; Zheng, Q.; Kuroda, C.; Wang, Q. Analogues from ligularia knorringiana. Molecules, 2012, 17, 5219. (79) Lee, T.-H.; Lu, C.-K.; Kuo, Y.-H.; Lo, J.-M.; Lee, C.-K. Unexpected novel pheophytin peroxides from the leaves of biden pilosa. Helv. Chim. Acta, 2008, 91, 79. (80) De Rosa, S.; De Stefano, S.; Scarpelli, P.; Zavodnik, N. Terpenes from the red alga sphaerococcus coronopifolius of the north Adriatic sea. Phytochem. 1988, 27, 1875. (81) Li, G.-H.; Li, L.; Duan, M.; Zhang, K.-Q. The chemical constituents of the fungus stereum sp. Chem. Biodiversity, 2006, 3, 210. (82) (a) Napolitano, J. G.; Gödecke, T.; Rodríguez-Brasco, M. F.; Jaki, B. U.; Chen, S. -N.; Lankin, D. C.; Pauli, G. F. The tandem of full spin analysis and qHNMR for the quality control of botanicals exemplified with ginkgo biloba. J. Nat. Prod. 2012, 75, 238. (b) Napolitano, J. G.; Lankin, D. C.; McAlpine, J. B.; Niemitz, M.; Korhonen, S. -P.; Chen, S. -N.; Pauli, G. F. Proton fingerprints portray molecular structures: enhanced description of the 1H NMR spectra of small molecules. J. Org. Chem. 2013, 78, 9963. (c) Gao, W.; Napolitano, J. G.; Lankin, D. C.; Kim, J. -Y.; Jin, Y. -Y.; Lee, H.; Suh, J. -W.; Chen, S. -N.; Pauli, G. F. Computer‐assisted 1H NMR analysis of the anti‐tuberculosis drug lead ecumicin. Magn. Reson. Chem. 2017, 55, 239. (83) (a) Pauli, G. F.; Niemitz, M.; Bisson, J.; Lodewyk, M. W.; Soldi, C.; Shaw, J. T.; Tantillo, D. J.; Saya, J. M.; Vos, K.; Kleinnijenhuis, R. A.; Hiemstra, H.; Chen, S. -N.; McAlpine, J. B.; Lankin, D. C.; Friesen, J. B. Toward structural correctness: aquatolide and the importance of 1D proton NMR FID archiving. J. Org. Chem. 2016, 81, 878. (b) Bisson, J.; Simmler, C.; Chen, S. -N.; Friesen, J. B.; Lankin, D. C.; McAlpine, J. B.; Pauli, G. F. Dissemination of original NMR data enhances reproducibility and integrity in chemical research. Nat. Prod. Rep. 2016, 33, 1028. (c) McAlpine, J.; Chen, S. N.; Kutateladze, A. G.; MacMillan, J.; Appendino, G.; Barison, A.; Beniddir, M.; Biavatti, M.; Bluml, S.; Boufridi, A.; Butler, M.; Capon, R.; Choi, Y.; Coppage, D.; Crews, P.; Crimmins, M.; Csete, M.; Dewapriya, P.; Egan, J.; Garson, M.; GentaJouve, G.; Gerwick, W.; Gross, H.; Harper, M.; Hermanto, P.; Hook, J.; Hunter, L.; Jeannerat, D.; Ji, N.Y.; Johnson, T.; Kingston, D.; Koshino, H.; Lee, H.W.; Lewin, G.; Li, J.; Linington, R.;

(51) Soonthornchareonnon, N.; Suwanborirux, K.; Bavovada, R.; Patarapanich, C.; Cassady, J. M. New cytotoxic 1-azaanthraquinones and 3-aminonaphthoquinone from the stem Bark of goniothalamus marcanii. J. Nat. Prod. 1999, 62, 1390. (52) Adam, W.; Hadjiarapoglou, L.; Peters, K.; Sauter, M. Dimethyldioxirane epoxidation of benzofurans: reversible thermal and photochemical valence isomerization between benzofuran epoxides, quinone methides, and benzoxetenes. J. Am. Chem. Soc.1993, 115, 8603. (53) http://dnp.chemnetbase.com (54) Chen, H.-L.; Wang, L.-W.; Su, H.-J.; Wei, B.-L.; Yang, S.Z.; Lin, C.-N. New terpenoids from amentotaxus formosana. Org. Lett. 2006, 8, 753. (55) Zhang, W.; Xu, L.; Yang, L.; Huang, Y.; Li, S.; Shen, Y. Phomopsidone A, a novel depsidone metabolite from the mangrove endophytic fungus phomopsis sp. A123. Fitoterapia, 2014, 96, 146. (56) Dinda, B.; Das, S. K.; Hajra, A. K. Naphthoquinones from the roots of plumbago rosea Linn. Indian J. Chem. 1995, 34B, 525. (57) Guo, S.; Tang, Y. P.; Duan, J. A.; Su, S. L.; Ding, A. W. Two new terpenoids from fruits of ziziphus jujube. Chinese Chem. Lett. 2009, 20, 197. (58) Lang, G.; Cole, A. L. J.; Blunt, j. W.; Robinson, W. T.; Munro, M. H. G. Excelsione, a depsidone from an endophytic fungus isolated from the New Zealand endemic tree knightia excels. J. Nat. Prod. 2007, 70, 310. (59) Wu, P.-L.; Su, G.-C.; Wu, T.-S. Constituents from the stems of aristolochia manshuriensis. J. Nat. Prod. 2003, 66, 996. (60) Shan, F.; Yin, Y.-Q.; Huang, F.; Huang, Y.-C.; Guo, L.-B.; Wu, Y.-F. A novel acridone akaloid from atalantia buxifolia. Nat. Prod. Res. 2013, 27, 1956. (61) Kabe, Y.; Takata, T.; Ueno, K.; Ando, W. Stereochemical studies of dioxetane formation with hindered olefins. J. Am. Chem. Soc. 1984, 106, 8174. (62) Liu,Q.-F.; Chen, W.-L.; Tang, J.; Zhao, W.-M. Novel bis(bibenzyl) and (propylphenyl)bibenzyl derivatives from dendrobium nobile. Helv. Chim. Acta 2007, 90, 1745. (63) Tiew, P.; Takayama, H.; Kitajima, M.; Aimi, N.; Kokpol, U.; Chavasiri, W. A novel neolignan, mansoxetane, and two new sesquiterpenes, mansonones R and S, from mansonia gagei. Tetrahedron Lett. 2003, 44, 6759. (64) Zhang, C.; Wang, M.; Lin, P.; Zhang, M.; Wang, Z.; Xu, L. A new bibenzyl Compound from Dendrobium gratiosissmum. J. Indian Chem. Soc.2007, 84, 714. (65) Otsuka, H.; Takeuchi, M.; Inoshiri, S.; Sato, T.; Yamasaki, K. Phenolic compounds from coix lachryma-jobi var. Ma-yuen. Phytochem. 1989, 28, 883. (66) Kim, K. H.; Choi, S. U.; Ha, S. K.; Kim, S. Y.; Lee, K. R. Biphenyls from Berberis koreana. J. Nat. Prod. 2009, 72, 2061. (67) Kim, C.S.; Subedi, L.; Kwon, O. K.; Kim, S. Y.; Yeo, E.-J.; Choi, S. U.; Lee, K. R. Isolation of bioactive biphenyl compounds from the twigs of chaenomeles sinensis. Bioorg. Med. Chem. Lett. 2016, 26, 351. (68) the rmsd value calculated for all the reported carbons; however, two carbon peaks were "not detected" in the experimental spectrum, which makes this revision tentative. (69) Chen, S.-G.; Chen, J.-J.; Gao, K. Prenylisoflavone derivatives from the roots of hedysarum scoparium. Chem. Pharm. Bull. 2007, 55, 1181. (70) Guilet, D.; Seraphin, D.; Rondeau, D.; Richomme, P.; Bruneton, J. Cytotoxic coumarins from calophyllum dispar. Phytochem. 2001, 58, 571. (71) Guo, Y.-G.; Xie, Y.-G.; Wu, G.-J.; Cheng, T.-F.; Zhu, S.12 L.; Yan, S.-K.; Jin, H.-Z.; Zhang, W.-D. Xylopidimers A–E, five ACS Paragon Plus Environment new guaiane dimers with various carbon skeletons from the roots of Xylopia vielana. ACS Omega, 2019, 4, 2047.

Page 13 of 13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Organic Chemistry Wist, J.; Yue, J. M.; Zhang, C.; Xu, Z.; Simmler, C.; Lankin, D.; Bisson, J.; Pauli, G. The Value of Universally Available Raw NMR Data for Transparency, Reproducibility, and Integrity in Natural Product Research. Nat. Prod. Rep. 2019, 36, 3

Liu, M.; McPhail, K.; Molinski, T.; Moore, B.; Nam, J. W.; Neupane, R.; Niemitz, M.; Nuzillard, J. M.; Oberlies, N.; Ocampos, F.; Pan, G.; Quinn, R.; Reddy, D.; Renault, J. H.; Rivera-Chávez, J.; Robien, W.; Saunders, C.; Schmidt, T.; Seger, C.; Shen, B.; Steinbeck, C.; Stuppner, H.; Sturm, S.; Taglialatela-Scafati, O.; Tantillo, D.; Verpoorte, R.; Wang, B.; Williams, C.; Williams, P.;

13

ACS Paragon Plus Environment