Group-assisted purification (GAP) chemistry for the synthesis of Velcade via asymmetric borylation of N-phosphinylimines

• Jian-bo Xie,
• Jian Luo,
• Timothy R. Winn,
• David B. Cordes and
• Guigen Li

Beilstein J. Org. Chem. 2014, 10, 746–751, doi:10.3762/bjoc.10.69

• hexane; the chiral N-phosphinyl auxiliary can be easily recovered after deprotection is finished. Several other N-phosphinylimines were also investigated for the asymmetric borylation reaction. The absolute configuration of the borylation product was confirmed by single crystal X-ray diffraction analysis

• and great stability in the catalytic borylation and deprotection reactions. GAP washing is found to enhance the diastereopurity of the borylation products in most cases. The absolute configuration of the borylation product in Velcade’s synthesis has been confirmed by single crystal X-ray diffraction

Copper–phenanthroline catalysts for regioselective synthesis of pyrrolo[3′,4′:3,4]pyrrolo[1,2-a]furoquinolines/phenanthrolines and of pyrrolo[1,2-a]phenanthrolines under mild conditions

• Rupankar Paira,
• Tarique Anwar,
• Maitreyee Banerjee,
• Yogesh P. Bharitkar,
• Shyamal Mondal,
• Sandip Kundu,
• Abhijit Hazra,
• Prakas R. Maulik and
• Nirup B. Mondal

Beilstein J. Org. Chem. 2014, 10, 692–700, doi:10.3762/bjoc.10.62

• ) also confirmed the structure. The relative orientations of H-1, H-18, H-19 and H-20 could be determined unambiguously by the single-crystal X-ray diffraction analysis of 10a; the ORTEP diagram is presented in Figure 2. No other diastereomer could be detected. The plausible mechanism of this

Self-assembly of metallosupramolecular rhombi from chiral concave 9,9’-spirobifluorene-derived bis(pyridine) ligands

• Rainer Hovorka,
• Sophie Hytteballe,
• Torsten Piehler,
• Georg Meyer-Eppler,
• Filip Topić,
• Kari Rissanen,
• Marianne Engeser and
• Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 432–441, doi:10.3762/bjoc.10.40

• obtained in an approximate 1.5:1.5:1 ratio which corresponds to an amplification of the homochiral assemblies by a factor of approximately three as evidenced by NMR spectroscopy and mass spectrometry. The racemic homochiral assemblies could also be characterised by single crystal X-ray diffraction

• second bis(pyridine) ligand (S)-6 in a two-fold Suzuki reaction. Metal coordination After the successful synthesis we mixed solutions of ligands 3 and 6 and [(dppp)Pd(OTf)2] or [(dppp)Pt(OTf)2] and characterised the resulting complexes by 1H, 31P, 1H 2D-DOSY NMR, ESI-MS, and single crystal X-ray

• diffraction to investigate if the desired rhomboid complexes are formed and whether we can observe any degree of self-sorting in the self-assembly processes of the racemic samples. The ESI-MS spectra recorded from the complex solutions showed the successful formation of the expected dinuclear [(dppp)2M2(L)2

The difluoromethylene (CF₂) group in aliphatic chains: Synthesis and conformational preference of palmitic acids and nonadecane containing CF₂ groups

• Yi Wang,
• Ricardo Callejo,
• Alexandra M. Z. Slawin and
• David O’Hagan

Beilstein J. Org. Chem. 2014, 10, 18–25, doi:10.3762/bjoc.10.4

• . Palmitic acids 6a and 6c were crystalline solids and single crystal X-ray diffraction data were obtained for these compounds. As described above analogue 6b was amorphous in nature and despite considerable effort a single crystal could not be obtained for 6b. The resultant structures for 6a and 6c are

Diastereoselectivity in the Staudinger reaction of pentafluorosulfanylaldimines and ketimines

• Alexander Penger,
• Cortney N. von Hahmann,
• Alexander S. Filatov and
• John T. Welch

Beilstein J. Org. Chem. 2013, 9, 2675–2680, doi:10.3762/bjoc.9.303

• of the ketene (A in Scheme 4) appears to be influenced by avoidance of unfavorable interaction of the ketene with the sterically demanding SF5 group. Previously it was found in single crystal X-ray diffraction studies that the pentafluorosulfanyl group [48] is predictably orthogonal to a carbonyl

• pentafluorosulfanyl β-amino acids and suggest a path to the preparation of more extensively functionalized SF5-containing β-lactams. The 1,2-lk stereochemistry of 7a as determined by single crystal X-ray diffraction. Thermal ellipsoids are set at 50% probability. The stereochemistry of 7c, 1,2-lk,lk (Si, Si-S), as

• determined by single crystal X-ray diffraction studies. Thermal ellipsoids are set at 50% probability. (a) Complete structure of 7c. (b) PMP protecting group hidden for clarity. Synthesis of 2-pentafluorosulfanylaldehydes by addition of SF5Cl to enol ethers. Reaction of pentafluorosulfanylaldimines with

Reaction of 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithiethane with N-vinyl compounds

• Viacheslav A. Petrov and
• Will Marshall

Beilstein J. Org. Chem. 2013, 9, 2615–2619, doi:10.3762/bjoc.9.295

• was confirmed by single crystal X-ray diffraction. Keywords: 1-(hexafluoroisopropyl)-3-vinyl-1,3-dihydro-2H-imidazole-2-thione; 2,2,4,4-terakis(trifluoromethyl)-1,3-dithiethane; 4-amino-2,2-bis(trifluoromethyl)thietanes; organo-fluorine; Introduction Hexafluorothioacetone (HFTA) and

• purified 3b was established by single crystal X-ray diffraction (Figure 1). Interestingly, the 19F and 1H NMR spectra of both compounds 3a and 3b show two sets of signals, probably being a result of restricted rotation around the C–N bond in the amide fragment, similar to restricted rotation of –N(CH3)2 in

• a significantly lower rotation barrier around the C–N bond in these two materials. The structures of both 3c and 3d were established by single crystal X-ray diffraction. Compounds 3b and 3e were also prepared in 56–60% yield by using a one-step process in which dimer 1 was generated by the reaction

Sequential Diels–Alder/[3,3]-sigmatropic rearrangement reactions of β-nitrostyrene with 3-methyl-1,3-pentadiene

• Peter A. Wade,
• Alma Pipic,
• Matthias Zeller and
• Panagiota Tsetsakos

Beilstein J. Org. Chem. 2013, 9, 2137–2146, doi:10.3762/bjoc.9.251

• combined chromatographic and recrystallization methods. The structure of nitro compound 12a,b is based on spectral data. However, isomer identification required single-crystal X-ray diffraction analysis, performed on the enriched sample (12a,b 91.4:8.6 ratio, respectively). The ternary adduct 12a,b is a

Synthesis of the reported structure of piperazirum using a nitro-Mannich reaction as the key stereochemical determining step

• James C. Anderson,
• Andreas S. Kalogirou,
• Michael J. Porter and
• Graham J. Tizzard

Beilstein J. Org. Chem. 2013, 9, 1737–1744, doi:10.3762/bjoc.9.200

• unambiguously assigned by single crystal X-ray diffraction but the spectroscopic data did not match those reported for the natural product. The structure of the natural product must therefore be revised. Keywords: alkaloid; aza-Henry; natural products; nitro-Mannich; piperazinone; stereoselective synthesis

Isolation and X-ray characterization of palladium–N complexes in the guanylation of aromatic amines. Mechanistic implications

• Abdessamad Grirrane,
• Hermenegildo Garcia and
• Eleuterio Álvarez

Beilstein J. Org. Chem. 2013, 9, 1455–1462, doi:10.3762/bjoc.9.165

• coordinated anilines 1a–c (see Supporting Information File 1, Figures S1–S3); these are compatible with the proposed structure for these intermediates. Complex 3a derived from 1a has been recently characterized by single-crystal X-ray diffraction [21] showing similar coordination to trans-dichlorobis(4

α-Bromodiazoacetamides – a new class of diazo compounds for catalyst-free, ambient temperature intramolecular C–H insertion reactions

• Åsmund Kaupang and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2013, 9, 1407–1413, doi:10.3762/bjoc.9.157

• resolved their structures by single-crystal X-ray diffraction. The diazoacetamides 3d and 3f crystallised as their (Z)-rotamers. These data have recently been reported [42][43]. The diazoacetamides were brominated at −5 °C with NBP in the presence of DBU and passed through a dry-ice-cooled plug of silica

Anionic cascade reactions. One-pot assembly of (Z)-chloro-exo-methylenetetrahydrofurans from β-hydroxyketones

• István E. Markó and
• Florian T. Schevenels

Beilstein J. Org. Chem. 2013, 9, 1319–1325, doi:10.3762/bjoc.9.148

• -derivative 36 were obtained as a 1:5 mixture of diastereoisomers that could be separated (Scheme 6). Their structure was unambiguously established by single-crystal X-ray diffraction analysis, as shown in Figure 1. Increasing the steric hindrance at the tertiary alcohol site resulted in the exclusive

• unambiguously established as the spirocyclic dimer 41 by single-crystal X-ray diffraction analysis. It is noteworthy that a single diastereoisomer was generated in this transformation. The formation of these unique compounds can be rationalized as depicted in Scheme 8. Under acidic conditions, the (Z)-chloro

• established by single-crystal X-ray diffraction analysis (Figure 2). Once again, increasing the steric effect around the tertiary alcohol function of the (Z)-chloro-exo-methylenetetrahydrofurans has a profound influence on the fate of the condensation reaction. A plausible mechanistic rationale is provided in

Methylidynetrisphosphonates: Promising C₁ building block for the design of phosphate mimetics

• Vadim D. Romanenko and
• Valery P. Kukhar

Beilstein J. Org. Chem. 2013, 9, 991–1001, doi:10.3762/bjoc.9.114

• salts (Figure 1) [7]. Structural features of the trisphosphonate 18 were studied by NMR spectroscopy and by single-crystal X-ray diffraction. Only one 31P NMR signal is observable for three equivalent phosphonate moieties in CHCl3. In contrast, the 31P solid-state NMR spectrum of 18 revealed three

Facile synthesis of functionalized spiro[indoline-3,2'-oxiran]-2-ones by Darzens reaction

• Qin Fu and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 918–924, doi:10.3762/bjoc.9.105

• spectra and were further confirmed by single-crystal X-ray diffraction determination of the compound 3c (Figure 1) and 4a (Figure 2). It should be pointed out that some of the spiro epoxyoxindoles 3a–h have been previously prepared by other methods and the related references are also listed in Table 2

Direct alkenylation of indolin-2-ones by 6-aryl-4-methylthio-2H-pyran-2-one-3-carbonitriles: a novel approach

• Sandeep Kumar,
• Ramendra Pratap,
• Abhinav Kumar,
• Brijesh Kumar,
• Vishnu K. Tandon and
• Vishnu Ji Ram

Beilstein J. Org. Chem. 2013, 9, 809–817, doi:10.3762/bjoc.9.92

• product entirely different from 5, 6 and 7. The isolated product was finally characterized by single-crystal X-ray diffraction as (2Z,5E)-5-aryl-3-methylthio-5-(2-oxoindolin-3-ylidene)pent-2-enenitrile 8. The reaction is initiated with Michael addition at C6 followed by ring opening with elimination of

A new synthetic access to 2-N-(glycosyl)thiosemicarbazides from 3-N-(glycosyl)oxadiazolinethiones and the regioselectivity of the glycosylation of their oxadiazolinethione precursors

• El Sayed H. El Ashry,
• El Sayed H. El Tamany,
• Mohy El Din Abdel Fattah,
• Mohamed R. E. Aly,
• Ahmed T. A. Boraei and
• Axel Duerkop

Beilstein J. Org. Chem. 2013, 9, 135–146, doi:10.3762/bjoc.9.16

• anomeric protons of the N-glycosides 29, 30 indicate that β-configuration is still retained here. X-ray analysis Single-crystal X-ray diffraction experiments yielded unambiguous confirmations of the structural assignments of the S-glycoside 23, the 2-N-(glycosyl)thiosemicarbazide 29, and the

Inclusion of the insecticide fenitrothion in dimethylated-β-cyclodextrin: unusual guest disorder in the solid state and efficient retardation of the hydrolysis rate of the complexed guest in alkaline solution

• Dyanne L. Cruickshank,
• Natalia M. Rougier,
• Raquel V. Vico,
• Susan A. Bourne,
• Elba I. Buján,
• Mino R. Caira and
• Rita H. de Rossi

Beilstein J. Org. Chem. 2013, 9, 106–117, doi:10.3762/bjoc.9.14

• )phosphorothioate] and the host compound heptakis(2,6-di-O-methyl)-β-cyclodextrin (DIMEB) was prepared and its structure elucidated by single-crystal X-ray diffraction. This revealed two independent host molecules in the asymmetric unit. In one of these, the cavity is occupied by two disordered guest components

Synthesis of spiro[dihydropyridine-oxindoles] via three-component reaction of arylamine, isatin and cyclopentane-1,3-dione

• Yan Sun,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 8–14, doi:10.3762/bjoc.9.2

• -crystal X-ray diffraction study performed for the compound 1b (Figure 1). It should be pointed out that the structure of the obtained spiro compounds is very interesting, in which the oxindole was connected to the ortho-position of the amino group of arylamine. It is well known that the one-pot reactions

• be separated from the reaction system. On the other hand, the reaction of α-naphthylamine also gave good yields of spiro compound 1l (Table 1, entry 12). The structures of spiro compounds 1a–1l were fully characterized by 1H and 13C NMR, HRMS, and IR spectra and were further confirmed by a single

Determination of the relative configuration of tropinone and granatanone aldols by using TBDMS ethers

• Ryszard Lazny,
• Aneta Nodzewska,
• Katarzyna Sidorowicz and
• Przemyslaw Kalicki

Beilstein J. Org. Chem. 2012, 8, 1877–1883, doi:10.3762/bjoc.8.216

• was determined as exo,syn by comparison of NMR data of the aldol isomers, in particular vicinal coupling constants and shifts corresponding to the side-chain CH group, with data of related TBDMS derivatives and confirmed by single-crystal X-ray diffraction. Keywords: aldol reaction; exo–endo

Facile synthesis of functionalized tetrahydroquinolines via domino Povarov reactions of arylamines, methyl propiolate and aromatic aldehydes

• Jing Sun,
• Hong Gao,
• Qun Wu and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2012, 8, 1839–1843, doi:10.3762/bjoc.8.211

• -crystal X-ray diffraction performed for the compound 1c (Figure 1). The 1H NMR spectra of compounds 1a–1m usually show two doublets and one triplet shift for the three cyclic CH units at the tetrahydroquinoline core. For example, in the 1H NMR spectrum of 1a the triplet at 3.09 ppm belongs to the proton

• methoxy group and with weak electron-withdrawing chloro or bromo groups reacted efficiently to give the expected products. The structures of the above-prepared functionalized tetrahydroquinolines 1a–1m were characterized by 1H and 13C NMR, MS, HRMS and IR spectra and were further confirmed by single

Highly enantioselective access to cannabinoid-type tricyles by organocatalytic Diels–Alder reactions

• Stefan Bräse,
• Nicole Volz,
• Franziska Gläser and
• Martin Nieger

Beilstein J. Org. Chem. 2012, 8, 1385–1392, doi:10.3762/bjoc.8.160

• of imidazolidinone catalysts, inspired by the work of MacMillan, achieved good yields up to 66% and enantiomeric excesses up to 98%. Experimental Crystal structure determinations The single-crystal X-ray diffraction study was carried out on a Nonius Kappa-CCD (9a, 16) or Bruker-Nonius APEXII

Synthesis of axially chiral oxazoline–carbene ligands with an N-naphthyl framework and a study of their coordination with AuCl·SMe₂

• Feijun Wang,
• Shengke Li,
• Mingliang Qu,
• Mei-Xin Zhao,
• Lian-Jun Liu and
• Min Shi

Beilstein J. Org. Chem. 2012, 8, 726–731, doi:10.3762/bjoc.8.81

• its structure was established by single-crystal X-ray diffraction studies (Figure 4; Supporting Information File 2). The crystal data of Au(1)–C(7) (1.991(5) Å) is a typical Au–CNHC bond length, in-line with those of other reported examples [16][17][18][19][20][21]. Furthermore, the angle of I(1)–Au(1

Stereoselective, nitro-Mannich/lactamisation cascades for the direct synthesis of heavily decorated 5-nitropiperidin-2-ones and related heterocycles

• Pavol Jakubec,
• Dane M. Cockfield,
• Madeleine Helliwell,
• James Raftery and
• Darren J. Dixon

Beilstein J. Org. Chem. 2012, 8, 567–578, doi:10.3762/bjoc.8.64

• followed by single-crystal X-ray diffraction studies of both isomers allowed unambiguous determination of the relative stereochemical configurations in each case. For more details of the elucidation of the relative configuration see Supporting Information File 1. The products were epimeric only at the

• –c to LiAlH4 in THF followed by quenching and treatment with HCOOH, spirocycles 11a–c were obtained in good yields. The chemoselectivity of the reduction was unambiguously confirmed by single-crystal X-ray diffraction studies of 11c. Furthermore, the use of an excess of DIBAL at room temperature

Self-assembly of Ru₄ and Ru₈ assemblies by coordination using organometallic Ru(II)₂ precursors: Synthesis, characterization and properties

• Sankarasekaran Shanmugaraju,
• Dipak Samanta and
• Partha Sarathi Mukherjee

Beilstein J. Org. Chem. 2012, 8, 313–322, doi:10.3762/bjoc.8.34

• salts in high yields and were characterized fully by multinuclear (1H, 13C and 19F) NMR, infrared (IR) and electrospray ionization mass spectrometry (ESIMS). In addition, the molecular structure of macrocycle 2a was established unequivocally by single-crystal X-ray diffraction analysis and adopts a

• molecular structure of the tetranuclear metallamacrocycle [(p-cymene)4Ru4(μ-η4-oxalato)2(L)]4+(O3SCF3−)4 (2a) was unambiguously determined by single-crystal X-ray diffraction analysis. Single crystals of 2a of high enough quality for X-ray diffraction were grown by slow vapor diffusion of diethyl ether into

• -crystal X-ray diffraction analysis, which reveals a tetranuclear geometry with the dimensions of 5.53 Å × 12.39 Å. In addition to their synthesis and characterization, the UV–vis absorption and cyclic voltammetry studies are reported. Results and Discussion Synthesis and characterization of the

A ferrocene redox-active triazolium macrocycle that binds and senses chloride

• Nicholas G. White and
• Paul D. Beer

Beilstein J. Org. Chem. 2012, 8, 246–252, doi:10.3762/bjoc.8.25

• , 597.2239. X-ray crystallography Single crystal X-ray diffraction data for 3 were collected by using synchrotron radiation (λ = 0.6889 Å) at the Diamond Light Source, Beam I19. The diffractometer was equipped with a Cryostream N2 open-flow cooling device [19] and the data were collected at 100(2) K. A

Regioselectivity in the multicomponent reaction of 5-aminopyrazoles, cyclic 1,3-diketones and dimethylformamide dimethylacetal under controlled microwave heating

• Kamal Usef Sadek,
• Ramadan Ahmed Mekheimer,
• Tahany Mahmoud Mohamed,
• Moustafa Sherief Moustafa and
• Mohamed Hilmy Elnagdi

Beilstein J. Org. Chem. 2012, 8, 18–24, doi:10.3762/bjoc.8.3

• single-crystal X-ray diffraction [25][26] (Figure 1, Figure 2 and Table 1, Table 2, Table 3). With this result in hand, we went on to study the scope of such multicomponent reactions with several substituted 5-aminopyrazoles and cyclic 1,3-diketones. Thus, the reaction of 1b–f with 2a,b and 3, under the

• established by single-crystal X-ray diffraction of compounds 6e,g (Figure 3, Figure 4 and Table 3, Table 4) [27][28]. A proposed mechanism to account for the formation of products 6 is illustrated in Scheme 2. The base-catalyzed reaction of cyclic 1,3-diketones 2 with DMFDMA 3 gave the enaminone 7, which