Strong hyperconjugative interactions limit solvent and substituent influence on conformational equilibrium: the case of cis-2-halocyclohexylamines

• Camila B. Francisco,
• Cleverton S. Fernandes,
• Ulisses Z. de Melo,
• Roberto Rittner,
• Gisele F. Gauze and
• Ernani A. Basso

Beilstein J. Org. Chem. 2019, 15, 818–829, doi:10.3762/bjoc.15.79

• layer was added NaOH until pH ≈ 14 and the product extracted exhaustively with CH2Cl2 (6 × 20 mL). The crude mixture was purified by silica-gel column chromatography (acetone/chloroform 10% for Cl and 25% for Br), and the cis isomer was isolated corresponding to a yellowish liquid for Cl (0.04 g, 15

An improved synthesis of adefovir and related analogues

• David J. Jones,
• Eileen M. O’Leary and
• Timothy P. O’Sullivan

Beilstein J. Org. Chem. 2019, 15, 801–810, doi:10.3762/bjoc.15.77

• (Table 2, entries 8, 12, 13, 15 and 16). The same regioselectivity was observed when the reaction was performed in either NMP or DMF, even though adenine (3) was more soluble in NMP. No reaction was observed in acetonitrile, acetone or ethyl acetate, presumably due to the insolubility of adenine (3) at

• electrophile in 14 means that the critical alkylation step is conducted at room temperature. Additionally, the preparation of chloride 19 is a solventless reaction and the subsequent conversion of 19 to iodide 14 takes place in acetone, a green solvent. Our route also produces fewer byproducts and is higher

Tuning the stability of alkoxyisopropyl protection groups

• Zehong Liang,
• Henna Koivikko,
• Mikko Oivanen and
• Petri Heinonen

Beilstein J. Org. Chem. 2019, 15, 746–751, doi:10.3762/bjoc.15.70

• of these acetone-based acetal groups are faster removed than a dimethoxytrityl group, and they are easier to cleave completely in solution. The structural variation allows steering of the stability and lipophilicity of the compounds in some range. Keywords: acetal; hydrolysis; protecting groups

• . Some structural modifications have been introduced to overcome the chirality problem, e.g., the methoxytetrahydropyranyl group suggested in 1970’s for a substitute of THP in nucleoside chemistry [4][5]. For protection of highly sensitive compounds acetone-based acetals can be applied. However, of these

• aimed at tuning the properties of acetone-based acetal protecting groups at nucleoside hydroxy functions. We have carried out a systematic kinetic study on the hydrolytic lability of five different 2-alkoxypropan-2-yl groups installed in the 5’- and 3’-hydroxy groups of a 2’-deoxynucleoside. We are well

New sesquiterpenoids from the South China Sea soft corals Clavularia viridis and Lemnalia flava

• Qihao Wu,
• Yuan Gao,
• Meng-Meng Zhang,
• Li Sheng,
• Jia Li,
• Xu-Wen Li,
• Hong Wang and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2019, 15, 695–702, doi:10.3762/bjoc.15.64

• compounds are presented. Results and Discussion The frozen bodies of the two soft corals C. viridis and L. flava were cut into pieces and exhaustively extracted with acetone. The Et2O-soluble portion of the acetone extracts were chromatographed repeatedly over silica gel, Sephadex LH-20, and RP-HPLC to

• . viridis and L. flava are deposited at the Shanghai Institute of Materia Medica, CAS, under registration Nos. 13XS-49 and 13XS-52, respectively. Extraction and isolation The lyophilized bodies of C. viridis (80 g, dry weight) were minced into pieces and exhaustively extracted with acetone at room

• , dry weight) were cut into pieces and extracted exhaustively with acetone at room temperature (6 × 2.0 L). The organic extract was evaporated to give a brown residue, which was then partitioned between H2O and Et2O. The upper layer was concentrated under reduced pressure to give a brown residue 8.0 g

Design, synthesis and spectroscopic properties of crown ether-capped dibenzotetraaza[14]annulenes

• Krzysztof M. Zwoliński and
• Julita Eilmes

Beilstein J. Org. Chem. 2019, 15, 617–622, doi:10.3762/bjoc.15.57

• equilibrated with chloroform. The column was firstly eluted isocratically with a mixture of chloroform and acetone (1:1, v/v) to remove any unreacted traces of α,ω-dibromoalkoxy macrocyclic derivatives 2a or 2b. The second band containing undesired site products was eluted isocratically with a mixture of

Selective benzylic C–H monooxygenation mediated by iodine oxides

• Kelsey B. LaMartina,
• Haley K. Kuck,
• Linda S. Oglesbee,
• Asma Al-Odaini and
• Nicholas C. Boaz

Beilstein J. Org. Chem. 2019, 15, 602–609, doi:10.3762/bjoc.15.55

• intermediate to decompose into phenol and acetone under acidic conditions [62]. Use of a less acidic solvent and lower reaction temperature drastically increased the selectivity for 2-phenyl-2-propanol in the NHPI-catalyzed oxidation of cumene [57]. The reason why tertiary benzylic C–H bonds, which are weaker

Synthesis and fluorescent properties of N(9)-alkylated 2-amino-6-triazolylpurines and 7-deazapurines

• Andrejs Šišuļins,
• Jonas Bucevičius,
• Yu-Ting Tseng,
• Irina Novosjolova,
• Kaspars Traskovskis,
• Ērika Bizdēna,
• Huan-Tsung Chang,
• Sigitas Tumkevičius and
• Māris Turks

Beilstein J. Org. Chem. 2019, 15, 474–489, doi:10.3762/bjoc.15.41

• % for N(9)-alkylated products. Both methodologies produced a mixture of N(9)- and N(7)-alkylated isomers from which the major N(9) product was easily separated by column chromatography [42][43][44][45][46][47]. Alkylated products were used in SNAr reactions with NaN3 in acetone or DMF, giving good to

• , CDCl3) δ 153.3, 152.9, 151.7, 145.9, 130.8, 44.7, 31.6, 29.8, 28.6, 26.6, 22.5, 14.0 ppm; HRMS–ESI (m/z): [M + H]+ calcd for C12H17Cl2N4, 287.0825; found, 287.0826. Azidation: NaN3 (5.88 g, 90.5 mmol, 3.0 equiv) was added to a solution of 9-alkyl-2,6-dichloro-9H-purine (30 mmol, 1.0 equiv) in acetone

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• . Addition of acetone to the hot reaction mixture immediately upon completion of the glycosylation and subsequent filtration of a precipitated product and repeated washing with acetone made it possible to isolate the anomerically pure β-4a as a free-flowing powder, while the α-anomer and other impurities

• remained in the acetone washings. This patent also divulges the synthesis of 2,3,5-tri-O-acetyl-D-ribofuranosyl chloride (β/α ratio is 6:4) using an extruder with the aim of developing a continuous production of compound 4a. Deacetylation of 4a to give the desired β-NR+Cl− salt was studied under acidic (aq

• generation of the protected β-NR+Br− 8a, which was isolated by crystallization from a 5:1 acetone/t-BuOMe mixture in 90% overall yield from 2a [27]. Note that dry acetonitrile was also used as a solvent in the glycosylation step instead of liquid SO2 but the yields of acetylated NR+Br− 8a were lowered (65

Synthesis of C₃-symmetric star-shaped molecules containing α-amino acids and dipeptides via Negishi coupling as a key step

• Sambasivarao Kotha and
• Saidulu Todeti

Beilstein J. Org. Chem. 2019, 15, 371–377, doi:10.3762/bjoc.15.33

• activated by using 3 M aq HCl, then filtered and washed with water (until neutral pH) followed by acetone. Large particles were crushed until a fine powder was formed and transferred into a round-bottomed flask and dried under vacuum with heating and the flask was filled with nitrogen. A portion of the

Annulation of 1H-pyrrole-2,3-diones by thioacetamide: an approach to 5-azaisatins

• Aleksandr I. Kobelev,
• Ekaterina E. Stepanova,
• Maksim V. Dmitriev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2019, 15, 364–370, doi:10.3762/bjoc.15.32

• products 3 were found to be labile and hard to isolate and purify. During our attempts to obtain pure compounds 3, we observed that their yellow acetone solutions became orange when stored for several hours in contact with the atmosphere, and after several days of storage, they had formed orange

• carried out in acetone, DMSO, and NMP under the typical procedure conditions from Table 1 (entries 1, 8, 11); different amounts of water (10, 20, 40, 80 and 100 µL) were added to the reaction mixtures, and the yields of the desired compound 4a were determined by HPLC. As a result, we found that the

• the yield of 4a was observed (in acetone the yield was 7% counting on PBT 2a). When an excessive amount of PBT 2a (double excess to thioacetamide) was used, a notable increase in yield of 4a was observed (the yield was 56% in acetone and 60% in DMSO counting on thioacetamide). These can indicate that

Chemical structure of cichorinotoxin, a cyclic lipodepsipeptide that is produced by Pseudomonas cichorii and causes varnish spots on lettuce

• Hidekazu Komatsu,
• Takashi Shirakawa,
• Takeo Uchiyama and
• Tsutomu Hoshino

Beilstein J. Org. Chem. 2019, 15, 299–309, doi:10.3762/bjoc.15.27

• , the 1H NMR signals of the monoacetate were well separated (600 MHz, acetone-d6, Supporting Information File 1, Figure S7). Therefore, the 1D and 2D NMR spectra of the monoacetate were analyzed to determine the overall structure. The 1H,1H COSY, TOCSY, NOESY, HMQC and HMBC spectra are shown in

• tetraacetate To further confirm the structure of cichorinotoxin, the tetraacetate was analyzed by NMR (600 MHz, acetone-d6). The majority of the 1H NMR signals of the tetraacetate (Figure S13A, Supporting Information File 1) were separated, which was not the case in the spectrum of the monoacetate. The TOCSY

• . The present studies gave some information of which structural units are required for the toxic activity, but are not sufficient. Further investigations are necessary to address the structure–activity relationship. Experimental General analytical methods NMR spectra were recorded in acetone-d6 on a

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• , dioxane/water; d) NaIO4, then NaOCl2, H2NSO3H; e) MeI, K2CO3, acetone; f) AcOH, H2O; g) NaOH, MeOH; h) PDC, DMF; i) CF3COOH, CH2Cl2; j) H2, 5% Pd/C, MeOH, H2O. Two-carbon homologation of the protected L-serine. Reagents and conditions: a) Fmoc-succinimide, Na2CO3, dioxane, H2O; b) (3-hydroxymethyl)-3

• , H2O; b) BuLi, THF; then H2C=CHCH2MgBr; c) L-selectride, THF; d) Me2C(OMe)2, PTSA, THF; e) O3, CH2Cl2, ether, then Ph3P; f) KMnO4, acetone, H2O; g) t-BuOH, N,N′-diisopropyl-O-tert-butylisourea, CH2Cl2; h) MeOH, HCl (gas); i) O2, Pt, AcOEt, H2O; j) electrochemical reduction. Synthesis of (2R,3S)-2 from

• O-benzyl-L-serine. Reagents and conditions: a) (CF3CH2O)2P(O)CH2COOMe, KHMDS, 18-crown-6; b) I2, MeCN; c) Bu3SnH, AIBN, benzene, reflux; d) H2, 10% Pd/C, ethanol; e) CrO3, acetone, then CH2N2, ether; f) 3 M HCl, 80 °C. Synthesis of (2S,3R)-2 employing a one-pot cis-olefination–conjugate addition

First synthesis of cryptands with sucrose scaffold

• Patrycja Sokołowska,
• Michał Kowalski and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2019, 15, 210–217, doi:10.3762/bjoc.15.20

• NMR data. In the spectrum recorded in acetone-d6, three signals at δ ≈ 60 ppm were seen. These signals were assigned (by HSQC experiments) to the benzyl groups connected to nitrogen atoms (-NCH2Ph), thus finally confirming the presence of a tripodal unit in the structure of the cryptand. Conclusion We

• , 67.94; H, 6.85; Cl, 6.43. 1’,2,3,3’,4,4’-Hexa-O-benzyl-6,6’-bis[2-(2-iodoethoxy)ethyl]sucrose (10): A solution of the above bis-chloro derivative 9 (813 mg, 0.74 mmol) in dry acetone (16 mL) containing dry sodium iodide (444.7 mg, 2.97 mmol) was stirred and boiled under reflux for 24 h. After cooling to

• rt, the precipitate was filtered off and washed with acetone. The combined acetone solutions were concentrated, and the residue was dissolved in CH2Cl2 (10 mL). The organic phase was washed with water and dried to give 10 (900 mg, 0.70 mmol, 95%) as an oil. [α] = +25.5; 1H NMR δ 5.65 (d, J1,2 = 3.6

Silanediol versus chlorosilanol: hydrolyses and hydrogen-bonding catalyses with fenchole-based silanes

• Falco Fox,
• Jörg M. Neudörfl and
• Bernd Goldfuss

Beilstein J. Org. Chem. 2019, 15, 167–186, doi:10.3762/bjoc.15.17

• kcal mol−1) and BIFOXSiCl(OH) (8) to BIFOXSi(OH)2 (9, Ea = 31.4 kcal mol−1) with high activation barriers, enforced by endo fenchone units. Crystal structure analyses of silanediol 9 with acetone show shorter hydrogen bonds between the Si–OH groups and the oxygen of the bound acetone (OH···O 1.88(3

• hydrogen bonds [74]. X-ray structures of BIFOXSi(OH)2 (9, Figure 16) and BIFOXSiCl(OH) (8, Figure 17) with co-crystallized acetone indicate the bonding behavior of the silanediols to carbonyl acceptors. Chlorosilanol 8 binds one acetone with a bonding length of 2.16(0) Å (H3···O4) and 2.89(4) Å (O3–H···O4

• additional molecule. For silanediols 2a and 2b Franz et al. observed hydrogen bond distances of 1.88 Å (H···O) and 2.68 Å (O–H···O) on average to guest molecules [41][42][43][44]. BIFOXSi(OH)2 (9, Figure 16) binds an acetone in a similar manner (O4’–H···O4–H···O6=C(CH3)2) with distances of 1.88(3) Å (H4···O6

Asymmetric synthesis of a high added value chiral amine using immobilized ω-transaminases

• Antonella Petri,
• Valeria Colonna and
• Oreste Piccolo

Beilstein J. Org. Chem. 2019, 15, 60–66, doi:10.3762/bjoc.15.6

• boiling point byproduct acetone [2][3][4][5][6]. Since (R)- and (S)-selective TAs are available on the market, both enantiomers of the amine product are accessible. This point is particularly relevant since in most cases the pharmacological activity of a chiral drug is closely related to its absolute

Mechanistic studies of an L-proline-catalyzed pyridazine formation involving a Diels–Alder reaction with inverse electron demand

• Anne Schnell,
• J. Alexander Willms,
• S. Nozinovic and
• Marianne Engeser

Beilstein J. Org. Chem. 2019, 15, 30–43, doi:10.3762/bjoc.15.3

• Anne Schnell J. Alexander Willms S. Nozinovic Marianne Engeser University of Bonn, Kekulé-Institute of Organic Chemistry and Biochemistry, Gerhard-Domagk-Str. 1, D-53121 Bonn, Germany 10.3762/bjoc.15.3 Abstract The mechanism of an L-proline-catalyzed pyridazine formation from acetone and aryl

• -substituted tetrazines via a Diels–Alder reaction with inverse electron demand has been studied with NMR and with electrospray ionization mass spectrometry. A catalytic cycle with three intermediates has been proposed. An enamine derived from L-proline and acetone acts as an electron-rich dienophile in a [4

• -proline and the carbonyl substrate acetone [40]. Houk and co-worker [41] verified the mechanism with quantum mechanical calculations, thus giving rise to the “List–Houk” mechanism. A discussion about the role of oxazolidinones as isomeric species to enamines has been raised in the scientific community [42

A simple and effective preparation of quercetin pentamethyl ether from quercetin

• Jin Tatsuzaki,
• Tomohiko Ohwada,
• Yuko Otani,
• Reiko Inagi and
• Tsutomu Ishikawa

Beilstein J. Org. Chem. 2018, 14, 3112–3121, doi:10.3762/bjoc.14.291

• is also presented. Results and Discussion Reported per-O-methylation reactions and our re-examination Conventional methylation of phenolic compounds is generally performed with methyl iodide (MeI) or dimethyl sulfate (Me2SO4) in an aprotic polar solvent in the presence of a base. Although acetone and

• potassium carbonate (K2CO3) are generally selected as the solvent and base, acetone can be replaced with dimethylformamide (DMF) if the starting phenol is poorly soluble in acetone. To our knowledge four reactions [37][38][39][40] were found in the literature as successful per-O-methylations of quercetin (2

• ), among which the three carried out methylations under the conventional conditions (Table 1). Using MeI and K2CO3 in DMF QPE (1) was isolated in 86% yield [37] (run 1 in Table 1). Per-O-methylations using acetone as a solvent have also been reported. Reactions under reflux with MeI and K2CO3 in 0.2 M

1,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonation

• A. S. Antonov,
• A. F. Pozharskii,
• P. M. Tolstoy,
• A. Filarowski and
• O. V. Khoroshilova

Beilstein J. Org. Chem. 2018, 14, 2940–2948, doi:10.3762/bjoc.14.273

• -arylketimines of 1,8-bis(dimethylamonio)naphthalene with a different number of methoxy groups in an aromatic substituent were investigated in solution by NMR (acetone, DMSO, MeCN), in solid state by X-ray analysis and in the gas phase by DFT calculations. Both mono- and diprotonated species were considered. It

• –7c) species were investigated by 1H NMR spectroscopy in DMSO-d6, CD3CN and acetone-d6 in a wide range of temperatures. Results obtained in solutions were compared to single crystal X-ray structures and calculated equilibrium geometries of isolated molecules in a vacuum. Results and Discussion

• . Structural investigations The structural investigations started with a 1H NMR analysis of the imines 4a–7a in acetone-d6, CD3CN and DMSO-d6 in a wide range of temperatures. The main attention was paid to the chemical shift and the shape of the C=NH and NMe2 groups’ signals. Upon temperature decrease, the NH

Synthesis of pyrrolidine-based hamamelitannin analogues as quorum sensing inhibitors in Staphylococcus aureus

• Jakob Bouton,
• Kristof Van Hecke,
• Reuven Rasooly and
• Serge Van Calenbergh

Beilstein J. Org. Chem. 2018, 14, 2822–2828, doi:10.3762/bjoc.14.260

• II (5 mol %), 1,2-DCE, 50 °C; c) K2OsO4·2H2O, NMO, acetone/H2O 3:1, rt; d) 2-methoxypropene, CSA (cat.), THF, rt; e) PhSH, K2CO3, MeCN, 50 °C; f) Boc2O, Et3N, CH2Cl2, rt; g) TBAF, THF, rt; h) Ms-Cl, Et3N, CH2Cl2, 0 °C; i) NaN3, DMF, 60 °C; j) PMe3, H2O, THF, rt; k) 2-chlorobenzoyl chloride, Et3N

Synthesis of mono-functionalized S-diazocines via intramolecular Baeyer–Mills reactions

• Miriam Schehr,
• Daniel Hugenbusch,
• Tobias Moje,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2018, 14, 2799–2804, doi:10.3762/bjoc.14.257

• functionalization such as cross coupling, peptide coupling or further functionalization. The photoswitchable properties of the S-diazocines 1–5 were investigated using UV–vis and NMR spectroscopic methods. The photostationary states (PSS), half-lives (t1/2) and absorption maxima (λmax) were recorded in acetone and

• nπ* absorption maxima are in a range between 508 nm to 516 nm (for UV–vis spectra measured in acetone see Supporting Information File 1). The half-lives vary from 24.8 h to 6.7 d. For the carboxylic acid functionalized S-diazocine 4 the two isomers generated after irradiation with 405 nm could be

• study discussed in this publication. Comparison of the obtained S-diazocine yields using the reductive lead method or the Baeyer–Mills reaction. Photostationary states, absorption maxima and half-lives of S-diazocines 1–5 determined with UV–vis and NMR spectroscopy in acetone. Supporting Information

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• 110 °C under solvent-free conditions. The products were produced in very short reaction times and recrystallized in ethanol to give pure 1-amidoalkyl-2-naphthols 50 (Scheme 8). The reusability of the ionic liquid catalyst 3 was also studied. For this purpose, warm acetone was used to extract the

• demonstrated in Scheme 12. Initially, 69 was formed using the reaction between 1,4-diazabicyclo[2.2.2]octane (67) and (3-chloropropyl)triethoxysilane (68) in refluxing acetone for 12 hours. In the next step, 70 was produced using the reaction between SiO2 and 69 in refluxing toluene for 8 h. Finally, silica

• heated to reflux for 24 h. After cooling down to room temperature, the solution was filtered, washed with 1 N HCl and acetone, and then dried. The resulted material was named as graphene (GR, 143). In order to sulfonate the GR (143), sodium nitrite and sulfanilic acid (144) were added to a sonicated

Assembly of fully substituted triazolochromenes via a novel multicomponent reaction or mechanochemical synthesis

• Robby Vroemans,
• Yenthel Verhaegen,
• My Tran Thi Dieu and
• Wim Dehaen

Beilstein J. Org. Chem. 2018, 14, 2689–2697, doi:10.3762/bjoc.14.246

• furnished both regioisomers in poor yields since the chromanones 7 and 8 are known to be unstable under the triazolization conditions [36]. Hence, no further attempts were made to improve these yields. Additionally, NH-triazole 9 could be alkylated using benzyl bromide and potassium carbonate in acetone

Quinolines from the cyclocondensation of isatoic anhydride with ethyl acetoacetate: preparation of ethyl 4-hydroxy-2-methylquinoline-3-carboxylate and derivatives

• Nicholas G. Jentsch,
• Jared D. Hume,
• Emily B. Crull,
• Samer M. Beauti,
• Amy H. Pham,
• Julie A. Pigza,
• Jacques J. Kessl and
• Matthew G. Donahue

Beilstein J. Org. Chem. 2018, 14, 2529–2536, doi:10.3762/bjoc.14.229

• quinolines of type 10 via C→D, the ethyl acetopyruvate has two carbonyls a and b as depicted in 13 that result in regioisomeric products upon ring closure. The desired quinoline 11 requires ring closure onto carbonyl b. To that end, ethyl sodioacetopyruvate was prepared via Claisen condensation of acetone

Semi-synthesis and insecticidal activity of spinetoram J and its D-forosamine replacement analogues

• Kai Zhang,
• Jiarong Li,
• Honglin Liu,
• Haiyou Wang and
• Lamusi A

Beilstein J. Org. Chem. 2018, 14, 2321–2330, doi:10.3762/bjoc.14.207

• solutions were prepared by weighting manufactured analogues and dissolving them in acetone. Dosing solutions were then prepared by diluting stock solutions to different concentrations with 0.01% Triton X-100 aqueous solution. Cabbage leaves were then soaked in the dosing solutions for 10 s, dried, and

Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds

• Liudmila L. Rodina,
• Xenia V. Azarova,
• Jury J. Medvedev,
• Dmitrij V. Semenok and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2018, 14, 2250–2258, doi:10.3762/bjoc.14.200

• for up to 6.5 h (control of the reacted diazodiketone 1 by TLC). Thereupon the reaction mixture was dried over magnesium sulfate, the solvent completely distilled off in vacuum and the residue separated by column chromatography (SiO2, eluent: petroleum ether → petroleum ether/acetone 8:1) to give the

• , 48.14, 46.14, 46.11, 46.04, 46.00, 31.2, 31.1, 24.4, 24.3 ppm; 1H NMR (400 MHz, acetone-d6, δ) 6.36–5.71 (m, 2H), 5.48 (dd, J = 6.6, 3.6 Hz, 1H), 4.14–3.75 (m, 2H), 3.46–3.01 (m, 5H), 2.46–2.12 (m, 2H), 2.10–1.73 (m, 2H), 1.62–1.52 (m, 2H) ppm; 13C NMR (101 MHz, acetone-d6, δ) 199.8, 134.1, 133.7, 92.1