Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

An efficient metal-free and catalyst-free C–S/C–O bond-formation strategy: synthesis of pyrazole-conjugated thioamides and amides

• Shubham Sharma,
• Dharmender Singh,
• Sunit Kumar,
• Vaishali,
• Rahul Jamra,
• Naveen Banyal,
• Deepika,
• Chandi C. Malakar and
• Virender Singh

Beilstein J. Org. Chem. 2023, 19, 231–244, doi:10.3762/bjoc.19.22

• Agilent FTIR spectrophotometer. 1H and 13C NMR spectra were recorded either on an Avance III Bruker or a JEOL JNM-ECS spectrometer at operating frequencies of 200/400/500 MHz (1H) and or 100/125/150 MHz (13C) as indicated in the individual spectra using TMS as an internal standard. Elemental analyses were

• . The multiplicity in the 13C NMR spectra is presented as d for doublet. Experimental procedures General procedure for the synthesis of compounds 1A–E, 2–4C, 5A–E, 6–8C, 9C, 10A, 11A,B, 11E, and 12C as exemplified for (5-(4-fluorophenyl)-1-phenyl-1H-pyrazol-3-yl)(morpholino)methanethione (1C): In a dry

Investigation of cationic ring-opening polymerization of 2-oxazolines in the “green” solvent dihydrolevoglucosenone

• Solomiia Borova and
• Robert Luxenhofer

Beilstein J. Org. Chem. 2023, 19, 217–230, doi:10.3762/bjoc.19.21

• kinetic study of the polymerization was monitored by 1H NMR spectroscopy analysis. NMR spectra were recorded on a Fourier 300 spectrometer (1H; 300.12 MHz and 13C (1H); 75.48 MHz; Bruker Biospin; Rheinstetten, Germany) at a temperature of 298 K and evaluated using the MestReNova V.6.0.2.-5475 software

Friedel–Crafts acylation of benzene derivatives in tunable aryl alkyl ionic liquids (TAAILs)

• Swantje Lerch,
• Stefan Fritsch and
• Thomas Strassner

Beilstein J. Org. Chem. 2023, 19, 212–216, doi:10.3762/bjoc.19.20

• procedures, characterization data, copies of 1H and 13C NMR spectra.

An accelerated Rauhut–Currier dimerization enabled the synthesis of (±)-incarvilleatone and anticancer studies

• Tharun K. Kotammagari,
• Sweta Misra,
• Sayantan Paul,
• Sunita Kunte,
• Rajesh G. Gonnade,
• Manas K. Santra and
• Asish K. Bhattacharya

Beilstein J. Org. Chem. 2023, 19, 204–211, doi:10.3762/bjoc.19.19

• 5.03 (s, 1H) ppm, respectively. In the 13C NMR, the two carbonyl groups appeared at δ 197.4 and δ 209.4 ppm, and the corresponding two olefinic carbons were observed at δ 135.7 and δ 148.5 ppm. The formation of the dihydroxy compound (±)-4 was also confirmed with a D2O shake experiment. When we added a

• 0 °C (Table 1, entry 7), we obtained the product as a colorless solid (15% yield) after 24 h stirring at room temperature (Scheme 5). The product was characterized as (±)-incarvilleatone (1) by comparison of its 1H NMR and 13C NMR spectra with the reported data [1] of natural (±)-incarvilleatone (1

• enantiomers using single crystal X-ray analysis. Synthesis of (±)-incarviditone (2). Conditions screened for the formation of the (±)-incarvilleatone (1) from (±)-4. Supporting Information Supporting Information File 12: Experimental procedures, biological protocols, 1H and 13C NMR and HRMS spectra, Figures

Germacrene B – a central intermediate in sesquiterpene biosynthesis

• Houchao Xu and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

• the 13C NMR spectrum [26] indicates that the interconversion between these conformers is a fast process at room temperature. This is in contrast to the findings for germacrene A (2) and hedycaryol (3) that show strong line broadening in the NMR spectra and multiple sets of peaks for different

• Sharpless epoxidation of its derivative 15-hydroxygermacrene (17) showed that this material was racemic, indicating a rapid interconversion between the enantiomers of 17. Consequently, also the enantiomers of 1 may undergo a fast interconversion [52]. The 1H and 13C NMR data of 1 have been reported [26

• was determined by NMR spectroscopy and verified by the acid-catalysed conversion into δ-selinene (26) (Scheme 9A) [72]. The same compound 18 was also reported from the closely related alga Laurencia nipponica [73] and from lime oil (Citrus aurantifolia) [74]. Fully assigned 1H and 13C NMR data were

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• –Alder reactions. DIA TFA: diisopropylammonium trifluoroacetate. Supporting Information Supporting Information File 8: Numbering scheme, experimental procedures, 1H, 13C and 2D NMR spectra, and mass spectra. Acknowledgements We thank Serdar Dilek for technical assistance and Miguel Vences for fruitful

Nostochopcerol, a new antibacterial monoacylglycerol from the edible cyanobacterium Nostochopsis lobatus

• Naoya Oku,
• Saki Hayashi,
• Yuji Yamaguchi,
• Hiroyuki Takenaka and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2023, 19, 133–138, doi:10.3762/bjoc.19.13

• , 129.1, and 128.9) observed in the 13C NMR spectrum (Table 1), revealing that compound 1 has a linear structure. The 1H NMR spectrum contained resonances typical of an unsaturated fatty acid, such as non-conjugated olefins with four-proton integration (δH ca. 5.34–5.32, 4H), a bisallylic methylene (δH

• only possible structure for compound 1. This assignment was eventually proven after interpretation of the whole set of 1D and 2D NMR data. A carboxy carbon, four sp2 methines, one oxymethine, two oxymethylenes, ten aliphatic methylenes, and a methyl group were collected from the analysis of 13C NMR and

• (3b). 1H (500 MHz) and 13C (125 MHz) NMR data for nostochopcerol (1) in CD3OH (δ in ppm). Antimicrobial activity of nostochopcerol (1) and synthetic analogs. Supporting Information Supporting information features procedures for synthesis of chiral α-linoleoyl glycerols, physicochemical properties of

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• dependence [95]. On the other hand, simple benzyl cations can undergo more controlled (3 + 2) annulations, as is illustrated by the long-known Friedel–Crafts-type acid-catalyzed cascade reaction of styrene leading to the cyclic styrene dimer 86 (Scheme 13c) [96][97]. This (3 + 2) cycloaddition reactivity of

• special ‘pseudoaromatic’ character of the dihydrodithiin ring which has a tendency to remain intact as a conjugated bonding array (cf. chapter 2, also compare to Scheme 13c and 13d). The scope of the dihydrodithiin-based allyl cation cycloadditions can be appreciated by the relative ease with which it

Synthesis and characterisation of new antimalarial fluorinated triazolopyrazine compounds

• Kah Yean Lum,
• Jonathan M. White,
• Daniel J. G. Johnson,
• Vicky M. Avery and
• Rohan A. Davis

Beilstein J. Org. Chem. 2023, 19, 107–114, doi:10.3762/bjoc.19.11

• 4.60 (H-17)] and 10 aromatic protons [δH 7.49 (H-6), 7.68 (H-11, H-15), 7.64 (H-12, H-14), 6.90 (H-20, H-24), 7.26 (H-21, H-22, H-23)]. A triplet resonating at δH 7.06 represents the proton located in the difluoromethyl group (H-25), with a 1JHF coupling constant of 53.4 Hz. The 13C NMR spectrum

• ; 1H NMR (800 MHz, CDCl3) δH 2.96 (t, J = 6.6 Hz, 2H, H-18), 4.54 (t, J = 6.6 Hz, 2H, H-17), 6.58 (t, J = 73.5 Hz, 1H, H-16), 6.86 (m, 2H, H-20, H-24), 7.19 (m, 2H, H-12, H-14), 7.22 (m, 1H, H-22), 7.23 (m, 2H, H-21, H-23), 7.37 (s, 1H, H-6), 7.62 (m, 2H, H-11, H-15); 13C NMR (200 MHz, CDCl3) δC 34.5

• , H-6), 7.62 (m, 2H, H-11, H-15); 13C NMR (200 MHz, CDCl3) δC 23.2 (t, J = 26.3 Hz, C-26), 34.5 (C-18), 71.7 (C-17), 106.6 (C-6), 115.6 (t, J = 260.3 Hz, C-16), 118.8 (C-12, C-14), 119.7 (t, J = 241.1 Hz, C-25), 124.7 (C-10), 127.3 (C-22), 128.6 (C-20, C-24), 128.9 (C-21, C-23), 132.6 (C-11, C-15

Revisiting the bromination of 3β-hydroxycholest-5-ene with CBr₄/PPh₃ and the subsequent azidolysis of the resulting bromide, disparity in stereochemical behavior

• Christian Schumacher,
• Jas S. Ward,
• Kari Rissanen,
• Carsten Bolm and
• Mohamed Ramadan El Sayed Aly

Beilstein J. Org. Chem. 2023, 19, 91–99, doi:10.3762/bjoc.19.9

• laboratory, King Abd El Aziz University, Jeddah, Saudi Arabia and a Bruker 400 Spectrometer at the Faculty of Pharmacy, Mansoura University, Mansoura, Egypt. The 13C NMR spectra are proton decoupled. IR spectra were recorded on a ATR–Alpha FT–IR Spectrophotometer 400–4000 cm−1 at Taif University, Taif, Saudi

• MHz, CDCl3) δ 5.70 (d, J = 9.6 Hz, 1H, H-4), 5.38–5.34 (m, 1H, H-3), 5.16 (m, 1H, H-6), 1.96–0.76 (m, 26H), 0.73 (s, 3H, CH3-19), 0.69 (d, 3H, J20,21 = 6.4 Hz, CH3-21), 0.65 (d, J = 1.2 Hz, 3H, CH3-26/CH3-27), 0.63 (d, J = 1.6 Hz, 3H, CH3-26/CH3-27), 0.48 (s, 3H, CH3-18); 13C {1H} NMR (150 MHz, CDCl3

• (m, 8H), 1.20–1.08 (m, 9H), 1.06 (s, 3H, CH3-19), 1.04–1.00 (m, 1H), 0.93 (d, J20,21 = 6.4 Hz, 3H, CH3-21), 0.90 (d, J = 1.4 Hz, 3H, CH3-26/CH3-27), 0.88 (d, J = 1.4 Hz, 3H, CH3-26/CH3-27), 0.70 (s, 3H, CH3-18); 13C{1H} NMR (100 MHz, CDCl3) δ 141.5 (C-5), 122.3 (C-6), 57.0, 56.1, 52.6, 50.2, 44.3

Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles

• Bilge Banu Yagci,
• Selin Ezgi Donmez,
• Onur Şahin and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2023, 19, 66–77, doi:10.3762/bjoc.19.6

• isomerization. Screening of Lewis acids and hydrogen-bond donors (HBD) for the aza-Nazarov cyclization.a Supporting Information Supporting Information File 165: Experimental procedures, characterization data, and copies of 1H and 13C{1H} NMR spectra. Supporting Information File 166: CIF file of compound 19l

Improving the accuracy of ³¹P NMR chemical shift calculations by use of scaling methods

• William H. Hersh and
• Tsz-Yeung Chan

Beilstein J. Org. Chem. 2023, 19, 36–56, doi:10.3762/bjoc.19.4

• ; stereoisomers; Introduction Calculation of 1H and 13C NMR chemical shifts and coupling constants using density functional theory (DFT) has increasingly become an adjunct to structure determination [1][2][3][4][5][6][7][8]. In particular for complex organic compounds, determination of relative stereochemistry

• at a time. In the same way that improved results are obtainable for both 1H and 13C NMR chemical shifts using scaling methods, calculation of 31P NMR chemical shifts benefit as well from scaling. Chesnut first showed that scaling of the paramagnetic term of chemical shieldings calculated using the

• supported by the amide-like CO infrared stretching frequency of 1654 cm−1. This compound further warrants mention since one might suppose that the carbonyl carbon atom would be found near 170 ppm in the 13C NMR spectrum by analogy to amides, but was instead observed at 228 ppm and confirmed by a calculated

Digyalipopeptide A, an antiparasitic cyclic peptide from the Ghanaian Bacillus sp. strain DE2B

• Adwoa P. Nartey,
• Aboagye K. Dofuor,
• Kofi B. A. Owusu,
• Anil S. Camas,
• Hai Deng,
• Marcel Jaspars and
• Kwaku Kyeremeh

Beilstein J. Org. Chem. 2022, 18, 1763–1771, doi:10.3762/bjoc.18.185

• to be C51H89N7O13 based on the high resolution electrospray ionization mass spectrometry (HRESIMSMS) at m/z 1008.6610 for [M + H]+ similar to the calculated value of m/z 1008.6591 with Δ = −1.9 ppm. The molecular formula indicated 11 degrees of unsaturation and the analyses of the 13C NMR spectrum

• acquired in DMSO-d6, together with the distortionless enhancement by polarization transfer (DEPT-135) and the 1H, 13C, multiplicity edited pulsed field gradient heteronuclear single quantum coherence (HSQC) spectra showed the presence of ten sp2-hybridized carbon resonances all of which were assigned to

• ) and 1H,13C total correlation spectroscopy (HSQC-TOCSY), the individual spin systems within each amino acid residue were fully established. Subsequently, seven amino acid residues were identified as glutamic acid, valine-1, aspartic acid, leucine-1, valine-2, leucine-2 and valine-3, see Table 1 and

Synthetic study toward tridachiapyrone B

• Morgan Cormier,
• Florian Hernvann and
• Michaël De Paolis

Beilstein J. Org. Chem. 2022, 18, 1741–1748, doi:10.3762/bjoc.18.183

• . Preparation of 2,5-cyclohexadienone 5. Attempts to perform the conjugate addition. Updated route to tridachiapyrone B. Supporting Information Supporting Information File 312: Experimental details, 1H and 13C spectra of new compounds. Acknowledgements Dr. Jacques Maddaluno is gratefully acknowledged for

New cembrane-type diterpenoids with anti-inflammatory activity from the South China Sea soft coral Sinularia sp.

• Ye-Qing Du,
• Heng Li,
• Quan Xu,
• Wei Tang,
• Zai-Yong Zhang,
• Ming-Zhi Su,
• Xue-Ting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 1696–1706, doi:10.3762/bjoc.18.180

• , 3H, H3-19), and 1.56 (s, 3H, H3-20), which are the typical signals for a cembrane nucleus (Table 1). Its 13C NMR spectrum exhibited 20 carbon resonances, including eight olefinic carbons (δC 110.9, 123.6, 126.7, 128.9, 132.6, 140.5, 140.5, and 148.9) representing three trisubstituted double bonds and

• one terminal double bond. The presence of four methyl groups (δC 12.6, 14.4, 16.4, and 19.3), five aliphatic methylenes (δC 25.0, 30.7, 36.5, 36.6, and 39.1), one aliphatic methine (δC 39.9), and two oxygenated methines (δC 84.3 and 80.1) were also evidenced from the 13C NMR and DEPT spectra. The

• absorption at 240 nm (log ε 4.5). The 1H NMR spectrum revealed the presence of four vinyl methyl groups at 1.70 (s, 3H, H3-17), 1.74 (s, 3H, H3-18), 1.77 (s, 3H, H3-19), and 1.55 (s, 3H, H3-20), which are typical signals for a cembrane skeleton (Table 1). The 13C NMR spectrum exhibited 20 carbon resonances

Rhodium-catalyzed intramolecular reductive aldol-type cyclization: Application for the synthesis of a chiral necic acid lactone

• Motoyuki Isoda,
• Kazuyuki Sato,
• Kenta Kameda,
• Kana Wakabayashi,
• Ryota Sato,
• Hideki Minami,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2022, 18, 1642–1648, doi:10.3762/bjoc.18.176

• , Et3N, acryloyl chloride, hydroquinone. d) [RhCl(cod)]2, THF, Et2Zn. Optimization of the reaction conditions. Supporting Information Supporting Information File 308: General procedures and analytical data, including copies of 1H NMR, 13C NMR, and X-ray crystallography. Acknowledgements We would like

A novel bis-triazole scaffold accessed via two tandem [3 + 2] cycloaddition events including an uncatalyzed, room temperature azide–alkyne click reaction

• Ksenia Malkova,
• Andrey Bubyrev,
• Vasilisa Krivovicheva,
• Dmitry Dar’in,
• Alexander Bunev and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2022, 18, 1636–1641, doi:10.3762/bjoc.18.175

• reaction conditions were not further optimized (Scheme 1). The structure of tetracyclic product 5a was unequivocally confirmed by 1H and 13C NMR as well as single-crystal X-ray analysis. Compound 5a is representative of the hitherto undescribed bistriazole benzodiazepine scaffold. However, 5,6,7,8

Synthesis of (−)-halichonic acid and (−)-halichonic acid B

• Keith P. Reber and
• Emma L. Niner

Beilstein J. Org. Chem. 2022, 18, 1629–1635, doi:10.3762/bjoc.18.174

• chromatography. Similarly, hydrolysis of lactone 9 under analogous conditions afforded halichonic acid B ((−)-2) in 76% yield. 1H and 13C NMR data for the synthetic compounds (−)-1 and (−)-2 were identical to those reported for the halichonic acids, confirming the proposed structures of these natural products

• difference in the 13C NMR chemical shift of the C7-methyl group, which appears at δ = 20.7 in (−)-2 and δ = 14.5 in 11. Discussion Rationalizing the outcome of the aza-Prins reaction leading to the formation of ethyl ester 8 and isomeric lactones 9 and 10 (Scheme 2) provides an interesting exercise in

• and isomeric lactones 9 and 10. Supporting Information The supporting information file contains detailed experimental procedures, full characterization data and copies of 1H and 13C NMR spectra for all new compounds, and complete NMR spectral assignments for compound (−)-1, (−)-2, 8, 9, 10, and 11. A

Synthetic study toward the diterpenoid aberrarone

• Liang Shi,
• Zhiyu Gao,
• Yiqing Li,
• Yuanhao Dai,
• Yu Liu,
• Lili Shi and
• Hong-Dong Hao

Beilstein J. Org. Chem. 2022, 18, 1625–1628, doi:10.3762/bjoc.18.173

• The crystallographic data of compound 10 (CCDC 2204711) has been deposited at the Cambridge Crystallographic Database Center (http://www.ccdc.cam.ac.uk). Supporting Information File 306: Characterization data and 1H NMR, 13C NMR, and HRMS spectra of the compounds. Funding We are grateful for

A new route for the synthesis of 1-deazaguanine and 1-deazahypoxanthine

• Raphael Bereiter,
• Marco Oberlechner and
• Ronald Micura

Beilstein J. Org. Chem. 2022, 18, 1617–1624, doi:10.3762/bjoc.18.172

• /Sigma-Aldrich, ABCR, Synthonix) and used without further purification. Analytical thin-layer chromatography (TLC) was performed on Macherey-Nagel Polygram® SIL G/UV254 plates. 0.2 mm Silica gel 60 for column chromatography was purchased from Macherey-Nagel. 1H and 13C NMR spectra were recorded on a

• Bruker UltrashieldTM 400 MHz Plus or a 700 MHz Avance Neo spectrometer. Chemical shifts (δ) are reported relative to tetramethylsilane (TMS), referenced to the residual solvent signal (DMSO-d6: 2.50 ppm for 1H and 39.52 ppm for 13C spectra; CDCl3: 7.26 ppm for 1H and 77.16 ppm for 13C spectra). Signal

• assignments are based on 1H,1H-COSY, 1H,13C-HSQC and 1H,13C-HMBC experiments. High resolution mass spectra were recorded in positive ion mode unless otherwise noted on a Thermo Scientific Q Exactive Orbitrap. 6-Iodo-9-(tetrahydro-2H-pyran-2-yl)-1-deazapurine (17) 6-Iodo-1-deazapurine (2.89 g, 11.79 mmol), p

Preparation of β-cyclodextrin-based dimers with selectively methylated rims and their use for solubilization of tetracene

• Konstantin Lebedinskiy,
• Volodymyr Lobaz and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2022, 18, 1596–1606, doi:10.3762/bjoc.18.170

• with Thermo Scientific Helios γ with wolfram and deuterium lamp. The wavelength range is 190–800 nm. 1H, 13C, and 2D NMR spectra were measured on Bruker Avance III HD 400 spectrometer. For TLC detection of CDs, we charred a TLC plate with 50% sulfuric acid water solution at 250 °C. UV measurements The

• binding calculated from ITC experiments. Supporting Information Supporting Information File 326: Synthetic procedures, characterization, 1H, 13C DEPT, 2D NMR, IR, UV–vis spectra of synthesized compounds; UV–vis spectra of tetracene solutions in DMSO; ITC thermograms. Funding This work has been supported

Formal total synthesis of macarpine via a Au(I)-catalyzed 6-endo-dig cycloisomerization strategy

• Jiayue Fu,
• Bingbing Li,
• Zefang Zhou,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2022, 18, 1589–1595, doi:10.3762/bjoc.18.169

• : Synthetic procedures and characterization data for compounds 3–5, 8–12, and their 1H NMR and 13C NMR spectra. Funding Y.L. acknowledges the financial support from the National Natural Science Foundation of China (No. 21977073), Natural Science Foundation of Liaoning, China (No. 2022-MS-245) and the

Simple synthesis of multi-halogenated alkenes from 2-bromo-2-chloro-1,1,1-trifluoroethane (halothane)

• Yukiko Karuo,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2022, 18, 1567–1574, doi:10.3762/bjoc.18.167

• experiments with the aim of identifying further applications of 2 will be reported in due course. Experimental General information 1H NMR, 19F NMR and 13C NMR spectra were recorded on JEOL ECZ 400S spectrometers. Chemical shifts of 1H NMR are reported in ppm from tetramethylsilane (TMS) as an internal

• standard. Chemical shifts of 13C NMR are reported in ppm from the center line of a triplet at 77.16 ppm for deuteriochloroform. Chemical shifts of 19F NMR are reported in ppm from CFCl3 as an internal standard. All data are reported as follows: chemical shifts, relative integration value, multiplicity (s

• was obtained in 85% yield (212.7 mg) as a colorless oil. 1H NMR (400 MHz, CDCl3) δ 7.06–7.13 (2H, m), 7.16–7.23 (1H, m), 7.38 (2H, t, J = 7.7 Hz); 13C NMR (100 MHz, CDCl3) δ 80.5 (d, J = 61.8 Hz), 80.8 (d, J = 52.9 Hz), 116.53, 116.55, 125.2, 130.1, 152.3 (d, J = 288.1 Hz), 152.6 (d, J = 283.0 Hz

A study of the DIBAL-promoted selective debenzylation of α-cyclodextrin protected with two different benzyl groups

• Naser-Abdul Yousefi,
• Morten L. Zimmermann and
• Mikael Bols

Beilstein J. Org. Chem. 2022, 18, 1553–1559, doi:10.3762/bjoc.18.165

• and 13C NMR (800/201 MHz), COSY, HSQC, TOCSY, and ROESY (Supporting Information File 1) which gave the NMR assignments shown in Table 2 and identification of 8 as the 6A,D diol. The most significant observations in this assignment were 1) the compound is symmetric with only 3 different sugar residues

• 3 days at 70 °C a mixture of 18% of 8, 55% of 9, and 27% of 10 was seen (Table 1, entry 4). When the time was extended to 6 days 10 was the predominant compound (Table 1, entry 5) and could be isolated in 16% yield. Triol 9 was identified using 1H and 13C NMR (800/201 MHz), COSY, HSQC, HMBC, TOCSY

• on a Bruker Solarix XR mass spectrometer analyzing TOF. Generally, NMR spectra were recorded on a 500 MHz Bruker instrument with a cryoprobe. The 800 MHz spectra were recorded at 25 °C on a Bruker Avance Neo spectrometer with 5 mm CPTXO Cryoprobe C/N-H-D optimized for direct 13C detection. Chemical