The enzymes of microbial nicotine metabolism

• Paul F. Fitzpatrick

Beilstein J. Org. Chem. 2018, 14, 2295–2307, doi:10.3762/bjoc.14.204

• catalyzed by DHNO is identical to that of the LHNO reaction, so that this enzyme was also initially identified as catalyzing the oxidation of the C2–C3 bond [17]. However, NMR analysis of the product has also recently established that DHNO catalyzes oxidation of the C2–N bond [24]. The sequence of DHNO from

Calix[6]arene-based atropoisomeric pseudo[2]rotaxanes

• Carmine Gaeta,
• Carmen Talotta and
• Placido Neri

Beilstein J. Org. Chem. 2018, 14, 2112–2124, doi:10.3762/bjoc.14.186

• spectrum of the mixture of 1 and 2+ in CDCl3 remained unchanged after 48 h at 298 K, thus showing that the system had reached the equilibrium condition. At this point, an apparent association constant of 6.2 ± 0.3 × 103 M–1 was calculated by quantitative 1H NMR analysis (tetrachloroethane as internal

• transferred into a NMR tube for 1D and 2D NMR spectra acquisition. Determination of apparent Kass value for pseudorotaxanes 2+1cone, 3+1cone and 3+11,2,3-alt, by quantitative 1H NMR analysis. The sample was prepared by dissolving calixarene 1 (3.0 × 10−3 M) and the ammonium TFPB salt 2+ or 3+ (3.0 × 10−3 M

• studies. Also in this case, after equilibration at 298 K for 24 h, this preference was reversed in favour of the 3+1cone atropoisomer, with a 3+1cone/3+11,2,3-alt ratio of 8/1. From the equilibrium mixture, an apparent association constant of 9.3 ± 0.4 × 102 M−1 was calculated by quantitative 1H NMR

Revisiting ring-degenerate rearrangements of 1-substituted-4-imino-1,2,3-triazoles

• James T. Fletcher,
• Matthew D. Hanson,
• Joseph A. Christensen and
• Eric M. Villa

Beilstein J. Org. Chem. 2018, 14, 2098–2105, doi:10.3762/bjoc.14.184

• measurement of each triazole-containing species as a relative molar fraction within the dynamic reaction mixtures was made using 1H NMR analysis. This was accomplished by integration of the distinguishable triazole signals for each iminotriazole and formyltriazole analog contained in this study. Signal

Cobalt-catalyzed nucleophilic addition of the allylic C(sp³)–H bond of simple alkenes to ketones

• Tsuyoshi Mita,
• Masashi Uchiyama,
• Kenichi Michigami and
• Yoshihiro Sato

Beilstein J. Org. Chem. 2018, 14, 2012–2017, doi:10.3762/bjoc.14.176

• were exclusively obtained (mixture of positional and geometric isomers) in 97% yield. It was shown by 1H NMR analysis that the mixture contained about 60% of 2-octadecene (E/Z mixture). Having established the reaction conditions, we then screened the scope and limitation of substituted acetophenone

First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones

• Grzegorz Mlostoń,
• Katarzyna Urbaniak,
• Paweł Urbaniak,
• Anna Marko,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2018, 14, 1834–1839, doi:10.3762/bjoc.14.156

• THF solutions at 60 °C by starting with equimolar amounts of substrates. After 2 h, completion of the reaction was confirmed by TLC, and, after typical workup, products 4 were obtained as colored solids in high yields (Scheme 1). The 1H NMR analysis revealed that the initially formed [4 + 2

• cycloadducts could be expected, but the 1H NMR analysis of the crude products showed that only one product was present in each case and, therefore, the studied [4 + 2] cycloaddition reactions occurred with complete regioselectivity. Based on the assumption that the nucleophilic S-atom of the thiochalcone

Synthesis of new tricyclic 5,6-dihydro-4H-benzo[b][1,2,4]triazolo[1,5-d][1,4]diazepine derivatives by [3⁺ + 2]-cycloaddition/rearrangement reactions

• Lin-bo Luan,
• Zi-jie Song,
• Zhi-ming Li and
• Quan-rui Wang

Beilstein J. Org. Chem. 2018, 14, 1826–1833, doi:10.3762/bjoc.14.155

• switched to a stronger oxidant, Pb(OAc)4. To our pleasure, hydrazone 11 was successfully oxidized to provide the required azoester 12. However, NMR analysis revealed that compound 12 was impure and contained also some cyclized byproduct [47]. Furthermore, it was discovered that compound 12 was quite

Heterogeneous acidic catalysts for the tetrahydropyranylation of alcohols and phenols in green ethereal solvents

• Ugo Azzena,
• Massimo Carraro,
• Gloria Modugno,
• Luisa Pisano and
• Luigi Urtis

Beilstein J. Org. Chem. 2018, 14, 1655–1659, doi:10.3762/bjoc.14.141

• -isopropyl-5-methylcyclohexanol ((−)-menthol, 1i). The reaction afforded an almost 1:1 mixture of only two diastereoisomers as determined by 1H and 13C NMR analysis of the crude reaction mixture, thus suggesting that it occurs with no epimerization at C1. This result was confirmed by submitting compound 3i

• to acid-catalyzed deprotection with H2SO4@SiO2 (25 wt % [33] as depicted in Scheme 3). Alcohol 1i, was recovered as a single stereoisomer, identical to the commercially available starting material, as determined by 1H and 13C NMR analysis of the crude reaction mixture (see Supporting Information File

Direct electrochemical generation of organic carbonates by dehydrogenative coupling

• Tile Gieshoff,
• Vinh Trieu,
• Jan Heijl and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2018, 14, 1578–1582, doi:10.3762/bjoc.14.135

• sufficient conversion for further studies. By optimization studies, we were able to produce 21% of the organic carbonate according to 1H NMR analysis on a 0.5 mmol scale (Scheme 2). Similar to the conversion of xylene, we also detected a weak signal of the corresponding side-chain functionalized product

Synthesis of pyrazolopyrimidinones using a “one-pot” approach under microwave irradiation

• Mark Kelada,
• John M. D. Walsh,
• Robert W. Devine,
• Patrick McArdle and
• John C. Stephens

Beilstein J. Org. Chem. 2018, 14, 1222–1228, doi:10.3762/bjoc.14.104

• funding. We also thank Barbara Woods and Orla Fenelon for HRMS analysis, and Dr. Ken Maddock for his assistance with NMR analysis.

Stereoselective nucleophilic addition reactions to cyclic N-acyliminium ions using the indirect cation pool method: Elucidation of stereoselectivity by spectroscopic conformational analysis and DFT calculations

• Koichi Mitsudo,
• Junya Yamamoto,
• Tomoya Akagi,
• Atsuhiro Yamashita,
• Masahiro Haisa,
• Kazuki Yoshioka,
• Hiroki Mandai,
• Koji Ueoka,
• Christian Hempel,
• Jun-ichi Yoshida and
• Seiji Suga

Beilstein J. Org. Chem. 2018, 14, 1192–1202, doi:10.3762/bjoc.14.100

• consistent with the Steven’s hypothesis. Keywords: cation pool; conformation; electroorganic synthesis; N-acyliminium ion; NMR analysis; piperidine; Introduction Cyclic amines are significant key motifs in pharmaceutical and natural products because a variety of compounds bearing those moieties exhibit

• between Hd and Hg. These results suggest that Hd adopts an axial and the phenyl group a pseudo-equatorial position at low temperature. The low temperature NMR analysis of C3, which has a phenyl group at 5-position, was next performed and the 1H NMR spectrum is depicted in Figure 2. An axial–axial coupling

• NMR analysis (Figure 3). The signal of Hf was observed as a triplet due to the axial–axial coupling with He and the geminal coupling with Hg, and these results indicate that the phenyl group of C5 is placed in the pseudo-axial position. The low temperature NMR measurements of N-acyliminium ions C2, C4

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• reaction of 2,3-benzotropone (12) with dimethyloxosulfonium methylide in yields of 35% and 28% and investigated the structural characterization of these compounds by extensive NMR analysis (Figure 7 and Scheme 34) [146]. In addition, carbonium ions 198–201, prepared via the protonation of 2,3-benzotropone

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

Hypervalent iodine(III)-mediated decarboxylative acetoxylation at tertiary and benzylic carbon centers

• Kensuke Kiyokawa,
• Daichi Okumatsu and
• Satoshi Minakata

Beilstein J. Org. Chem. 2018, 14, 1046–1050, doi:10.3762/bjoc.14.92

• previous report [25], a proposed reaction pathway is depicted in Scheme 5. At the beginning of the reaction, PhI(OAc)2 predominantly exists rather than 4, as confirmed by NMR analysis. Therefore, in the initial stage, PhI(OAc)2 preferentially undergoes decomposition with I2 to provide acetyl hypoiodite

Synthesis of a sucrose-based macrocycle with unsymmetrical monosaccharides "arms"

• Karolina Tiara,
• Mykhaylo A. Potopnyk and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2018, 14, 634–641, doi:10.3762/bjoc.14.50

• –Grubbs catalyst (II gen.) afforded the target macrocycle 25 in 26% yield (Scheme 4). The E-configuration of the newly created C=C-bond in the final product was proven by 1H NMR analysis (J15-15’ = 15.9 Hz). Conclusion In summary, we proposed an efficient method of the synthesis of a 31-membered

An air-stable bisboron complex: a practical bidentate Lewis acid catalyst

• Longcheng Hong,
• Sebastian Ahles,
• Andreas H. Heindl,
• Gastelle Tiétcha,
• Andrey Petrov,
• Zhenpin Lu,
• Christian Logemann and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 618–625, doi:10.3762/bjoc.14.48

• 1,2-diazine as well as 1,2,4,5-tetrazine. Its stability towards air and moisture was demonstrated by NMR analysis and enables its application in organic synthesis without using a glovebox. A new one-pot procedure for its synthesis was developed starting from 1,2-bis(trimethylsilyl)benzene, which will

Copper-catalyzed asymmetric methylation of fluoroalkylated pyruvates with dimethylzinc

• Kohsuke Aikawa,
• Kohei Yabuuchi,
• Kota Torii and
• Koichi Mikami

Beilstein J. Org. Chem. 2018, 14, 576–582, doi:10.3762/bjoc.14.44

• organic layer was dried over anhydrous Na2SO4 and evaporated under reduced pressure (350 mmHg). The concentrated solution was used without purification for the next protection reaction. The yield of alcohol product 2 was determined by 19F NMR analysis using benzotrifluoride (BTF) as an internal standard

• determined by 19F NMR analysis. p-Nitrobenzoylated alcohol 2a’ was purified by silica-gel column chromatography (EtOAc/hexane 1:40) as a colorless liquid (53% yield for 2 steps, 89% ee). 1H NMR (300 MHz, CDCl3) δ 8.34–8.31 (m, 2H), 8.24–8.20 (m, 2H), 4.33 (q, 4H, J = 6.9 Hz), 1.97 (d, 3H, J = 0.9 Hz), 1.28

• isomer 23.8 min. (S)-1-Ethoxy-3,3-difluoro-2-methyl-1-oxopropan-2-yl benzoate (2g’) Reaction temperature was −78 °C. The yield of alcohol 2g (89%) was determined by 19F NMR analysis. In the protection of alcohol, benzoyl chloride was used instead of p-nitrobenzoyl chloride. Benzoylated alcohol 2g’ was

Oxidative cycloaddition of hydroxamic acids with dienes or guaiacols mediated by iodine(III) reagents

• Hisato Shimizu,
• Akira Yoshimura,
• Keiichi Noguchi,
• Victor N. Nemykin,
• Viktor V. Zhdankin and
• Akio Saito

Beilstein J. Org. Chem. 2018, 14, 531–536, doi:10.3762/bjoc.14.39

• NMR analysis). As a further application of the iodine(III)-mediated oxidative cycloaddition reactions, the present method was extended to HDA reactions with masked o-benzoquinones (MOBs) generated by the oxidative dearomatization [26][27][28][29] of guaiacols with methanol (Scheme 2). Liao’s and other

Continuous multistep synthesis of 2-(azidomethyl)oxazoles

• Thaís A. Rossa,
• Nícolas S. Suveges,
• Marcus M. Sá,
• David Cantillo and
• C. Oliver Kappe

Beilstein J. Org. Chem. 2018, 14, 506–514, doi:10.3762/bjoc.14.36

• reaction mixture was quenched with NaHCO3 solution, extracted with ethyl acetate and concentrated under reduced pressure. The 1H NMR analysis of the crude product mixture revealed three major side products. Purification by column chromatography permitted the separation and isolation of each component

One-pot sequential synthesis of tetrasubstituted thiophenes via sulfur ylide-like intermediates

• Jun Ki Kim,
• Hwan Jung Lim,
• Kyung Chae Jeong and
• Seong Jun Park

Beilstein J. Org. Chem. 2018, 14, 243–252, doi:10.3762/bjoc.14.16

• intermediates 7, which are easily converted into the desired thiophenes 8, can be generated in situ by S-alkylation of the intermediate thiolate salts. By 1H NMR analysis of N,S-acetals 9 and methoxy group substitution of 9b, the formation of sulfur ylide-like intermediates was successfully demonstrated. The

Nucleophilic fluoroalkylation/cyclization route to fluorinated phthalides

• Masanori Inaba,
• Tatsuya Sakai,
• Shun Shinada,
• Tsuyuka Sugiishi,
• Yuta Nishina,
• Norio Shibata and
• Hideki Amii

Beilstein J. Org. Chem. 2018, 14, 182–186, doi:10.3762/bjoc.14.12

• (Scheme 4) [12]. Only diastereoisomer 6 was detected in the NMR analysis. Acid-promoted deprotection of hemiaminal 6 and subsequent oxidation of acetal 7 gave the enantiopure phthalide 1a in good yield. Although a high control of diastereoselectivity (using stoichiometric auxiliary strategy) was achieved

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• Cu catalysis. Trifluoromethylation of arylboronic acids reported by Sanford’s group. Isolated yield. aYields determined by 19F NMR analysis. Trifluoromethylation of arylboronic acids and vinylboronic acids reported by the group of Beller. Yields determined by 19F NMR analysis. aGC yield. bIsolated

Stereochemical outcomes of C–F activation reactions of benzyl fluoride

• Neil S. Keddie,
• Pier Alexandre Champagne,
• Justine Desroches,
• Jean-François Paquin and
• David O'Hagan

Beilstein J. Org. Chem. 2018, 14, 106–113, doi:10.3762/bjoc.14.6

• : Experimental protocols. Supporting Information File 132: 2H NMR analysis of enantiopurity. Acknowledgements NK and DOH acknowledge support from the University of St Andrews, Engineering and Physical Sciences Research Council (EPSRC, Grant No.: EP/L017911/1), and the EPSRC UK National Mass Spectrometry

Recent applications of click chemistry for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles

• Vivek Poonthiyil,
• Thisbe K. Lindhorst,
• Vladimir B. Golovko and
• Antony J. Fairbanks

Beilstein J. Org. Chem. 2018, 14, 11–24, doi:10.3762/bjoc.14.2

• AAT-AuNPs) was used. However, 1H NMR analysis of the AuNPs revealed that the particles had not reacted with the glycosyl azide. Following the report of Boisselier et al. [62], a stoichiometric amount of CuSO4·5H2O was then used, and the reaction was performed under a nitrogen atmosphere. Firstly a

Conformational preferences of α-fluoroketones may influence their reactivity

• Graham Pattison

Beilstein J. Org. Chem. 2017, 13, 2915–2921, doi:10.3762/bjoc.13.284

• that they show a high preference in polar solvents to attain a cis-conformation, which place C=O and C–F bonds in the same plane and unable to undergo favourable orbital interactions. Experimental NMR analysis was performed on a Bruker Avance III HD-400 system. Computational calculations were performed

The synthesis of the 2,3-difluorobutan-1,4-diol diastereomers

• Robert Szpera,
• Nadia Kovalenko,
• Kalaiselvi Natarajan,
• Nina Paillard and
• Bruno Linclau

Beilstein J. Org. Chem. 2017, 13, 2883–2887, doi:10.3762/bjoc.13.280

• resulted in 56% yield after column chromatography. 19F NMR analysis of the crude product showed a dr of 98:2 in favour of (±)-syn-4. However, given a diastereomerically pure starting material was used, this indicates that SN1 or neighbouring group participation pathways may have occurred, although only to