Azirinium ylides from α-diazoketones and 2H-azirines on the route to 2H-1,4-oxazines: three-membered ring opening vs 1,5-cyclization

• Nikolai V. Rostovskii,
• Mikhail S. Novikov,
• Alexander F. Khlebnikov,
• Galina L. Starova and
• Margarita S. Avdontseva

Beilstein J. Org. Chem. 2015, 11, 302–312, doi:10.3762/bjoc.11.35

• 60 °С: azirine 1c was completely consumed to give azadiene 3e isolated by column chromatography in 43% yield (Table 1, entry 5). The structure of azadiene 3e was confirmed by X-ray diffraction analysis (Figure 1). It should be noted that azadiene 3e in crystal exists in the s-trans-conformation

• characterized by standard spectral methods and the structures of adducts 6f and 7h were additionally confirmed by X-ray diffraction analysis (Figure 2). The reaction of diazoacetylacetone 2c with 2,3-diphenyl-2H-azirine (1a) provides oxazine 4i as a sole product (Table 1, entry 10). It was isolated with the

• conditions to the carbonyl group of oxazine 16. Actually, compound 17 formed in the reaction of a pure oxazine 16 with diazo compound 2c in the presence of Rh2(OAc)4. Its structure was assigned by standard spectral methods and confirmed by X-ray diffraction analysis (Figure 4). It was found that, when kept

Inclusion of trans-resveratrol in methylated cyclodextrins: synthesis and solid-state structures

• Lee Trollope,
• Dyanne L. Cruickshank,
• Terence Noonan,
• Susan A. Bourne,
• Milena Sorrenti,
• Laura Catenacci and
• Mino R. Caira

Beilstein J. Org. Chem. 2014, 10, 3136–3151, doi:10.3762/bjoc.10.331

• into a new vial, closed with a punctured polytop lid and was allowed to evaporate slowly on the benchtop or in an oven. The vial was sealed after crystals appeared. X-ray diffraction analysis All intensity data were collected on a Bruker KAPPA APEX II DUO diffractometer. In each case a single crystal

First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine

• Paweł Borowiecki,
• Daniel Paprocki and
• Maciej Dranka

Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322

• means of the assignment of the absolute configuration of the resolved enantiopure alcohol (S)-(+)-5 determined by a modified Mosher’s methodology, and was unambiguously confirmed by X-ray diffraction analysis. Optically active intermediates (S)-(+)-5 and (R)-(−)-7 achieved in this manner were

Formal total syntheses of classic natural product target molecules via palladium-catalyzed enantioselective alkylation

• Yiyang Liu,
• Marc Liniger,
• Ryan M. McFadden,
• Jenny L. Roizen,
• Jacquie Malette,
• Corey M. Reeves,
• Douglas C. Behenna,
• Masaki Seto,
• Jimin Kim,
• Justin T. Mohr,
• Scott C. Virgil and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2014, 10, 2501–2512, doi:10.3762/bjoc.10.261

• ]. The relative stereochemistry of dysidiolide (29) was determined via single-crystal X-ray diffraction analysis, revealing a molecule with six stereocenters, two of which are quaternary carbons [45]. Several groups have reported total syntheses of this natural product [47][48][49][50][51][52][53], three

• –Danheiser chemistry [66][67]. E) Rhazinilam (−)-Rhazinilam (44) has been isolated from various plants including Rhazya strica decaisne [68], Melodinus australis [69], and Kopsia singapurensis [70]. Shortly after the first isolation, its structure was elucidated by single crystal X-ray diffraction analysis

Synthesis of 2-trifluoromethylpyrazolo[5,1-a]isoquinolines via silver triflate-catalyzed or electrophile-mediated one-pot tandem reaction

• Xiaoli Zhou,
• Meiling Liu,
• Puying Luo,
• Yingjun Lai,
• Tangtao Yang and
• Qiuping Ding

Beilstein J. Org. Chem. 2014, 10, 2286–2292, doi:10.3762/bjoc.10.238

• reaction conditions gave the desired product 3b in good yield (86%, Table 2, entry 2). The structure of 3b was verified by 1H and 13C NMR, HRMS, as well as X-ray diffraction analysis (Figure 1, for details, see Supporting Information File 1). As expected, the substrates 1e–h with electron-withdrawing

• 13C NMR, HRMS, as well as X-ray diffraction analysis (Figure 1, for details, see Supporting Information File 1). Based on this one-pot tandem electrophilic cyclization/[3 + 2] cycloaddition reactions, highly functionalized pyrazolo[5,1-a]isoquinolines can be obtained via palladium-catalyzed cross

(CF₃CO)₂O/CF₃SO₃H-mediated synthesis of 1,3-diketones from carboxylic acids and aromatic ketones

• JungKeun Kim,
• Elvira Shokova,
• Victor Tafeenko and
• Vladimir Kovalev

Beilstein J. Org. Chem. 2014, 10, 2270–2278, doi:10.3762/bjoc.10.236

• unknown heterocycles 4а,b. Unambiguous evidence for the structure of heterocycle 4a was obtained by X-ray diffraction analysis [26]. The crystal structure of 4a is mediated by hydrogen bonds with a cation, a chloride anion and a solvating water molecule as participants (Figure 1). By acylation of 1

Derivatives of the triaminoguanidinium ion, 3. Multiple N-functionalization of the triaminoguanidinium ion with isocyanates and isothiocyanates

• Jan Szabo,
• Kerstin Karger,
• Nicolas Bucher and
• Gerhard Maas

Beilstein J. Org. Chem. 2014, 10, 2255–2262, doi:10.3762/bjoc.10.234

• (6c) reacted much more slowly than 6a,b. The molecular structure of 7a·3CH3CN in the solid state was established by a single crystal X-ray diffraction analysis and is shown in Figure 1 (vide infra for a discussion of structural details). It is interesting to note that the chloride anion is trapped

• ) 11b was isolated as a byproduct in 26% yield. The corresponding bis(arylthiourea) 11a could not be isolated, although its formation had been suggested by NMR spectra of the reaction mixture. The molecular structure of 10b was established by an X-ray diffraction analysis and is shown in Figure 4. The

Aryl substitution of pentacenes

• Andreas R. Waterloo,
• Anna-Chiara Sale,
• Dan Lehnherr,
• Frank Hampel and
• Rik R. Tykwinski

Beilstein J. Org. Chem. 2014, 10, 1692–1705, doi:10.3762/bjoc.10.178

• acenes can provide vital information about intermolecular interactions, single crystals of pentacenes 3a–d and 3g–j were grown and their solid-state arrangements determined by single crystal X-ray diffraction analysis (crystallographic details are provided in Supporting Information File 1). Pentacene 3a

Concise total synthesis of two marine natural nucleosides: trachycladines A and B

• Haixin Ding,
• Wei Li,
• Zhizhong Ruan,
• Ruchun Yang,
• Zhijie Mao,
• Qiang Xiao and
• Jun Wu

Beilstein J. Org. Chem. 2014, 10, 1681–1685, doi:10.3762/bjoc.10.176

• further unambiguously confirmed by X-ray diffraction analysis (Figure 3). This is the first report on the usage of SnCl4 as a regio- and stereoselective deprotection reagent in perbenzylated 5-deoxy-1-O-methylribofuranose. Based on these findings SnCl4 may prove useful for the regio- and stereoselective

Rasta resin–triphenylphosphine oxides and their use as recyclable heterogeneous reagent precursors in halogenation reactions

• Xuanshu Xia and
• Patrick H. Toy

Beilstein J. Org. Chem. 2014, 10, 1397–1405, doi:10.3762/bjoc.10.143

• trans configurations of the 9Ba and 9Bb were confirmed by X-ray diffraction analysis of the isolated products, and as was true for the Appel reactions described above, all the products were obtained in high purity simply by filtration to remove the polymer, and concentration of the filtrate. Our

Atherton–Todd reaction: mechanism, scope and applications

• Stéphanie S. Le Corre,
• Mathieu Berchel,
• Hélène Couthon-Gourvès,
• Jean-Pierre Haelters and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117

• chlorination such as the use of N-chlorosuccinimide or, as reported more recently, CuCl2 produced, in the latter case, 7-6 with full stereocontrol (Scheme 7-iii) as unambiguously determined by X-ray diffraction analysis [31]. The addition of nucleophilic species (amine, alcohol, alkyllithium, etc.) on 7-6 or

• and the stereochemistry of the products were unambiguously established by X-ray diffraction analysis. It is noteworthy that such coupling conditions have been extended to a wide variety of substrates including nitro-, methoxy-, trifluoromethylphenol or thiophenol with an almost similar reactivity

• hypothesis is strongly supported by X-ray diffraction analysis of a single crystal structure of the P–Cl intermediate species (Scheme 8). Thereafter, the reaction with phenol proceeds with an inversion of the configuration after a nucleophilic attack at the opposite side of the phosphorus–chlorine bond. In

Towards allosteric receptors – synthesis of β-cyclodextrin-functionalised 2,2’-bipyridines and their metal complexes

• Christopher Kremer,
• Gregor Schnakenburg and
• Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 814–824, doi:10.3762/bjoc.10.77

• [(CO)3Re(14)Cl] complex obtained by X-ray diffraction analysis. Unfortunately, we were neither able to coordinate rhenium(I) to our bipyridines 1–3 nor did we succeed to prepare the rhenium complex [(CO)3Re(1)Cl] by using [(CO)3Re(14)Cl] and reacting it with aminocyclodextrin 21. Next, we tried copper

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

• analysis. Experimental Standard operations for catalytic borylation and GAP: A 10 mL Schlenk tube was charged with crude imine 2, B2Pin2 (375 mg, 2 equiv), catalyst ICyCuOt-Bu (54 mg, 20 mol %) and 4 Å molecular sieves (~500 mg). The mixture was protected with argon atmosphere, followed by toluene (4 mL

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

Studies on the interaction of isocyanides with imines: reaction scope and mechanistic variations

• Ouldouz Ghashghaei,
• Consiglia Annamaria Manna,
• Esther Vicente-García,
• Marc Revés and
• Rodolfo Lavilla

Beilstein J. Org. Chem. 2014, 10, 12–17, doi:10.3762/bjoc.10.3

• monocrystal of the bis(imino)azetidine 3a was subjected to X-ray diffraction analysis and the solid state structure is depicted in Figure 1 [11]. This result confirms the structural features associated to this scaffold, and also raises some questions on the origin of the stereochemistry associated to the C=N

• that can account for the production of this rich structural outcome has been proposed. X-ray diffraction analysis of azetidine 3a. Azetidine formation from the interaction of imines with isocyanides. Reaction conditions. Stepwise mechanism for the formation of azetidine 3a. Manifold reaction mechanism

Synthetic scope and DFT analysis of the chiral binap–gold(I) complex-catalyzed 1,3-dipolar cycloaddition of azlactones with alkenes

• María Martín-Rodríguez,
• Luis M. Castelló,
• Carmen Nájera,
• José M. Sansano,
• Olatz Larrañaga,
• Abel de Cózar and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2013, 9, 2422–2433, doi:10.3762/bjoc.9.280

• as base and toluene as solvent at 120 °C. Polycyclic compound 15 was finally obtained in 50% yield as single diastereoisomer (Scheme 8). Despite being a solid product it was not possible to perform an X-ray diffraction analysis. Positive (CH derived from NPM with the CH derived from NMM) nOe

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

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

Use of 3-[¹⁸F]fluoropropanesulfonyl chloride as a prosthetic agent for the radiolabelling of amines: Investigation of precursor molecules, labelling conditions and enzymatic stability of the corresponding sulfonamides

• Reik Löser,
• Steffen Fischer,
• Achim Hiller,
• Martin Köckerling,
• Uta Funke,
• Aurélie Maisonial,
• Peter Brust and
• Jörg Steinbach

Beilstein J. Org. Chem. 2013, 9, 1002–1011, doi:10.3762/bjoc.9.115

• product 18. This compound was obtained in the form of crystals suitable for X-ray diffraction analysis. The molecular structure of 18 is shown in Figure 2A, confirming unambiguously its identity as N-(4-nitrophenyl)-3-fluoropropane-1-sulfonamide. Crystal data and structure refinement parameters are

One-pot tandem cyclization of enantiopure asymmetric cis-2,5-disubstituted pyrrolidines: Facile access to chiral 10-heteroazatriquinanes

• Ping-An Wang,
• Sheng-Yong Zhang and
• Henri B. Kagan

Beilstein J. Org. Chem. 2013, 9, 265–269, doi:10.3762/bjoc.9.32

• CH2Cl2, suitable for X-ray diffraction analysis. It was found that the ring-closing reaction took place during the heating process following N-methylation to provide the rigid 1-oxo-3-aza-10-azaquinane skeleton 7b as its ammonium salt. Compound 7b contains four stereogenic centers, and their

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

• its volatility (and hence toxicity) by conversion of the liquid pesticide into a solid phase. Experimental The compounds used in this study were purified as indicated before [6]. Crystal preparation and X-ray diffraction analysis Fenitrothion (1, 20 mg, ~0.072 mmol) was added to a saturated aqueous

Asymmetric synthesis of γ-chloro-α,β-diamino- and β,γ-aziridino-α-aminoacylpyrrolidines and -piperidines via stereoselective Mannich-type additions of N-(diphenylmethylene)glycinamides across α-chloro-N-sulfinylimines

• Gert Callebaut,
• Sven Mangelinckx,
• Pieter Van der Veken,
• Karl W. Törnroos,
• Koen Augustyns and
• Norbert De Kimpe

Beilstein J. Org. Chem. 2012, 8, 2124–2131, doi:10.3762/bjoc.8.239

• diastereoselectivity of the Mannich-type addition of glycinamides 4 across chiral α-chloro-N-p-toluenesulfinylaldimines 3 was independent of the base used. The absolute stereochemistry of (SS,2S,3S)-γ-chloro-α,β-diaminocarboxylamides syn-5 was unambiguously determined by means of an X-ray diffraction analysis of

Iridium-catalyzed intramolecular [4 + 2] cycloadditions of alkynyl halides

• Andrew Tigchelaar and
• William Tam

Beilstein J. Org. Chem. 2012, 8, 1765–1770, doi:10.3762/bjoc.8.201

• ] cycloadditions in which the relative stereochemistry was assigned by X-ray diffraction analysis [32] or GOESY NMR [33]. For both alkynyl bromide 1a and alkynyl chloride 1b (Table 3, entries 1 and 2) the reaction went to completion quite quickly; however, a decreased yield was seen in the cycloaddition of 1b

The crystal structure of the Dess–Martin periodinane

• Albert Schröckeneder,
• Desiree Stichnoth,
• Peter Mayer and
• Dirk Trauner

Beilstein J. Org. Chem. 2012, 8, 1523–1527, doi:10.3762/bjoc.8.172

• the first X-ray crystal structure of DMP (1). This could serve as a basis for computational investigations concerning the mechanism of the Dess–Martin oxidation. Results and Discussion The difficulty in obtaining suitable single crystals for X-ray diffraction analysis of DMP (1) may lie in the high

Approaches to α-amino acids via rearrangement to electron-deficient nitrogen: Beckmann and Hofmann rearrangements of appropriate carboxyl-protected substrates

• Sosale Chandrasekhar and
• V. Mohana Rao

Beilstein J. Org. Chem. 2012, 8, 1393–1399, doi:10.3762/bjoc.8.161

• . All products were generally purified chromatographically and fully characterized spectroscopically (including HRMS). In addition, two of the final carbamates (10a and 10b) were confirmed by X-ray diffraction analysis (Figure 2 and Table 4) [24]. The carbamates 10 apparently evidenced restricted