Preparation of pyridine-3,4-diols, their crystal packing and their use as precursors for palladium-catalyzed cross-coupling reactions

• Tilman Lechel,
• Irene Brüdgam and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2010, 6, No. 42, doi:10.3762/bjoc.6.42

• derivatives in good yields. The X-ray crystal structure analysis proved that a 1:1 mixture of pyridine-3,4-diols and their pyridin-4-one tautomers exist in the solid state. Subsequent conversion into bis(perfluoroalkanesulfonate)s were smoothly achieved. The obtained compounds were used as substrates for

• pyridine-3,4-diol side by a polar protic solvent such as methanol. Surprisingly, the X-ray crystal structure measurement of compound 2c [24] revealed that in the solid state a 1:1 ratio of diol and its pyridinone tautomer 2c′ is preferred. Figure 1 shows that two pyridine-3,4-diol molecules are in one

• ): δ = −68.4 (s, CF3) ppm. IR (KBr): ν = 3305 (≡C-H), 3000–2850 (=C-H, C-H), 2225–2105 (C≡C), 1765–1575 (C=C) cm−1. HRMS (ESI-TOF) calcd. for C14H13F3N [M+H]+: 252.0995; found 252.1009. X-ray crystal structure of compound 2c/2c′. Absorption and fluorescence spectra of compounds 4b and 4c. Deprotection

Prins fluorination cyclisations: Preparation of 4-fluoro-pyran and -piperidine heterocycles

• Guillaume G. Launay,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2010, 6, No. 41, doi:10.3762/bjoc.6.41

• . Prins fluorination reactions, at −20 °C, with cyclohexanol 8 using benzaldehyde and 4-nitrobenzaldehyde gave rise to the corresponding bicyclic products 9 with good diastereoselectivity (10/1) and in moderate yields (Table 4). The X-ray crystal structure of the predominant bicyclic diastereoisomer was

• accelerated under microwave conditions. X-ray crystal structure of syn-5a. X-ray crystal structure of the major bicyclic tetrahydropyran diastereoisomer 9b. X-ray crystal structure of the minor anti-piperidine product 14d. The C–F bond forming Prins reaction leading to 4-fluoropyrans [10]. Ring opening

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

Comparison of zwitterionic N-alkylaminomethanesulfonic acids to related compounds in the Good buffer series

• Robert D. Long,
• Newton P. Hilliard Jr,
• Suneel A. Chhatre,
• Tatiana V. Timofeeva,
• Andrey A. Yakovenko,
• Daniel K. Dei and
• Enoch A. Mensah

Beilstein J. Org. Chem. 2010, 6, No. 31, doi:10.3762/bjoc.6.31

• to the site of protonation in this compound (as confirmed by X-ray crystal structure). X-ray crystallographic structures of two members of the series are reported. Several of these compounds have pKa values that would indicate potential utility for buffering at pH levels below the normal

Novel loop-like aromatic compounds: a further step on the road to nanobelts and nanotubes

• Venkataramana Rajuri,
• Dariush Ajami,
• Gaston R. Schaller,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2010, 6, No. 30, doi:10.3762/bjoc.6.30

• and 7 using pyridazine, 1,2-bis(dibromomethyl)benzene and 2,3,4,5-tetrachlorothiophene-1,1-dioxide as dienes the loop-like molecules 2, 3, 5b, and 6 were obtained. All structures were verified by X-ray crystal structure analysis. ORTEP drawing of the crystal structures: a) 2 and b) 3. For additional

Self-association of an indole based guanidinium-carboxylate-zwitterion: formation of stable dimers in solution and the solid state

• Carolin Rether,
• Wilhelm Sicking,
• Roland Boese and
• Carsten Schmuck

Beilstein J. Org. Chem. 2010, 6, No. 3, doi:10.3762/bjoc.6.3

• DMSO, their stability is lower than of an analogous pyrrole based zwitterion 1. As revealed by the X-ray crystal structure the two binding sites in 2 cannot be planar due to steric interactions between the guanidinium group and a neighbouring aromatic CH. Hence the guanidinium moiety is twisted out of

Enantioselective synthesis of tricyclic amino acid derivatives based on a rigid 4-azatricyclo[5.2.1.0^2,6]decane skeleton

• Matthias Breuning,
• Tobias Häuser,
• Christian Mehler,
• Christian Däschlein,
• Carsten Strohmann,
• Andreas Oechsner and
• Holger Braunschweig

Beilstein J. Org. Chem. 2009, 5, No. 81, doi:10.3762/bjoc.5.81

• chiral ketone 9 was thus available in overall five steps and 47% yield from 10. The X-ray crystal structure of 9 is shown in Figure 3. Initial studies on the installation of the functionalized C1 side chain, as required for the amino acid derivatives 7, were done on racemic material and aimed at an

• 8, and the key intermediate 9. X-ray crystal structure of 9. X-ray data have been deposited with the Cambridge Crystallographic Data Centre (CCDC 743050). X-ray crystal structure of 8a•MeOH. X-ray data have been deposited with the Cambridge Crystallographic Data Centre (CCDC 742656). Synthesis of

[3.3]Dithia-bridged cyclophanes featuring a thienothiophene ring: synthesis, structures and conformational analysis

• Sabir H. Mashraqui,
• Yogesh Sanghvikar,
• Shailesh Ghadhigaonkar,
• Sukeerthi Kumar,
• Auke Meetsma and
• Elise Trân Huu Dâu

Beilstein J. Org. Chem. 2009, 5, No. 74, doi:10.3762/bjoc.5.74

• ]dithia-bridged cyclophanes; dynamic NMR analysis; thieno[2,3-b]thiophene; X-ray crystal structure; Introduction The synthesis, molecular structures and conformational dynamics of short-bridged cyclophanes continue to engage interest in supramolecular chemistry [1][2][3][4]. The study of the

• thienothiophene rings in 7 and 9 and both methyl and methoxyl substituents for case of 11. Single X-ray Crystal structure and conformational search of 11 The single-crystal structure of 11 was deduced by X-ray crystallography [32]. The space group of the molecular structure is P21/n, meaning the point group is 2

• dihedral angles viz. S1–C1–C17–S4, C17–S4–C18–C14, C10–S3–C9–C8 and C8–S2–C5–S1 for the most stable anti-11 are broadly similar to those of the cyclophane 11 derived from the X-ray data. Consequently, there is good correspondence between the X-ray crystal structure and the most stable conformation anti-11

Diastereoselective functionalisation of benzo-annulated bicyclic sultams: Application for the synthesis of cis-2,4-diarylpyrrolidines

• Susan Kelleher,
• Pierre-Yves Quesne and
• Paul Evans

Beilstein J. Org. Chem. 2009, 5, No. 69, doi:10.3762/bjoc.5.69

• solvent led to the formation of compound 17a, albeit in low yield, in which a molecule of the solvent has been incorporated (Entry 6). For X-ray crystal structure of 13a see Figure 2. The analogous functionalisation of alkene 5b was then considered. In toluene (Scheme 5, Entry 1), the optimal solvent for

• diastereoisomers. This sense of diastereoselectivity was confirmed by a series of NOE experiments and the single X-ray crystal structure obtained for compound 31 (see Figure 5 and crystallographic data). Poor conversion was observed when the one-pot reductive-palladium method, analogous to that described in Scheme

• ) [O2···C9: 2.850(2) Å]. X-ray crystal structure of 13a (Diamond representation). X-ray crystal structures of 18b and 19b (Diamond representations). X-ray structure of 26 (Diamond representation). X-ray crystal structure of 31 (Diamond representation). The diastereoselective intramolecular Heck

2-Phenyl- tetrahydropyrimidine- 4(1H)-ones – cyclic benzaldehyde aminals as precursors for functionalised β²-amino acids

• Markus Nahrwold,
• Arvydas Stončius,
• Anna Penner,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2009, 5, No. 43, doi:10.3762/bjoc.5.43

• employed in peptide chemistry as asparagine protective groups [52] and as proline mimetics [40]. The class of compounds described in this paper can therefore be considered as a versatile tool in peptide and amino acid chemistry. X-ray crystal structure of 10 [44]. Comparison of coupling constants (C5–C6

Synthesis of phosphonate and phostone analogues of ribose-1-phosphates

• Pitak Nasomjai,
• David O'Hagan and
• Alexandra M. Z. Slawin

Beilstein J. Org. Chem. 2009, 5, No. 37, doi:10.3762/bjoc.5.37

• 10 and 11. X-Ray crystal structure of cyclohexylammonium salt 8a. Biosynthetic pathway from fluoride ion to fluoroacetate 1 and 4-fluorothreonine 2 in S. cattleya [2]. Synthetic route A. Reagents and conditions: a) acetone, concd H2SO4 (cat.), 6 h, 86%; b) Deoxo-fluor™, DCM, 40 °C, 30 min, 84%; c

Synthesis of new C^α-tetrasubstituted α-amino acids

• Andreas A. Grauer and
• Burkhard König

Beilstein J. Org. Chem. 2009, 5, No. 5, doi:10.3762/bjoc.5.5

• 15 Acknowledgements We thank Dr. Manfred Zabel, University of Regensburg, for the X-ray crystal structure analysis. Support by the Fonds der Chemischen Industrie and the Deutsche Forschungsgemeinschaft is gratefully acknowledged.

Asymmetric synthesis of biaryl atropisomers by dynamic resolution on condensation of biaryl aldehydes with (−)-ephedrine or a proline- derived diamine

• Ann Bracegirdle,
• Jonathan Clayden and
• Lai Wah Lai

Beilstein J. Org. Chem. 2008, 4, No. 47, doi:10.3762/bjoc.4.47

• , 113.9, 93.6, 82.1, 65.4, 57.2, 56.5, 37.6, 14.5; m/z (CI) 390 (M+1, 100%). Mass measurement 389.1985, C25H27NO3 requires 389.1991. Anal. Calcd for C25H27NO3: C, 77.09, H, 6.99, N, 3.60; Found C, 76.79; H, 7.13; N, 3.66. [α]D25 −134.9 (c = 0.512, chloroform). X-ray crystal structure of 9a. X-ray data has

• been deposited with the Cambridge Crystallographic Data Centre: deposition number 693530. X-ray crystal structure of 10a. X-ray data has been deposited with the Cambridge Crystallographic Data Centre: deposition number 693529. Synthesis of racemic aldehydes. Diastereoisomeric imidazolidines and

Control of asymmetric biaryl conformations with terpenol moieties: Syntheses, structures and energetics of new enantiopure C₂-symmetric diols

• Y. Alpagut,
• B. Goldfuss and
• J.-M. Neudörfl

Beilstein J. Org. Chem. 2008, 4, No. 25, doi:10.3762/bjoc.4.25

• ] are often employed as chiral ligands in enantioselective synthesis. We recently reported the synthesis and the X-ray crystal structure of (M)-BIFOL [7] (biphenyl-2,2′-bisfenchol, Scheme 1) and its derivatives [8][9][10][11]. (M)-BIFOL exhibits, in a similar way as BINOLs, a flexible biaryl axis with M

• crystal structure of (M)-BIMOL. An acetone molecule, binding to the external OH group, is omitted for clarity. X-Ray crystal structure of (P)-BIVOL. A water molecule, binding to the external OH group, is omitted for clarity (cf. Scheme 3). X-Ray crystal structure of (P)-BICOL. A water molecule, binding to

• the external OH group, is omitted for clarity (cf. Scheme 3). X-Ray crystal structure of (P)-BIMEOL. An ethanol molecule, binding to the external OH group, is omitted for clarity (cf. Scheme 3) B3LYP/6-31++G**:AM1 optimized structure of (M)-BIMOL, Erel. = 0.0 kcal/mol. B3LYP/6-31++G**:AM1 optimized

Vinylogous Mukaiyama aldol reactions with 4-oxy-2-trimethylsilyloxypyrroles: relevance to castanospermine synthesis

• Roger Hunter,
• Sophie C. M. Rees-Jones and
• Hong Su

Beilstein J. Org. Chem. 2007, 3, No. 38, doi:10.1186/1860-5397-3-38

• sequence. Experimental See Supporting Information File 1 for full experimental data. Figure 5 describes the numbering system used in the experimental section. X-ray crystal structure of 6b. Structure of (+)-castanospermine 9. C-8/C-8a disconnection stategy for castanospermine synthesis. X-ray structure of

Reactions of glycidyl derivatives with ambident nucleophiles; part 2: amino acid derivatives

• Gerald Dyker,
• Andreas Thöne and
• Gerald Henkel

Beilstein J. Org. Chem. 2007, 3, No. 28, doi:10.1186/1860-5397-3-28

• carried out in the presence of air (for its X-ray crystal structure see Figure 1; X-ray data have been deposited at the Cambridge Crystallographic Data Centre; deposition number CCDC-214083; Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ

2-Arylhydrazononitriles as building blocks in heterocyclic synthesis: A novel route to 2-substituted- 1,2,3-triazoles and 1,2,3-triazolo[4,5-b]pyridines

• Saleh M. Al-Mousawi and
• Moustafa Sh. Moustafa

Beilstein J. Org. Chem. 2007, 3, No. 12, doi:10.1186/1860-5397-3-12

• refluxing 2a with hydroxylamine hydrochloride in DMF/piperidine afforded 1,2,3-triazoles whose structure was established by X-ray crystal structure. [11] On the other hand reacting 2b with hydroxylamine hydrochloride in DMF/piperidine afforded 5-amino-1,2,4-triazole via a rare Tiemann-like rearrangement. In

The vicinal difluoro motif: The synthesis and conformation of erythro- and threo- diastereoisomers of 1,2-difluorodiphenylethanes, 2,3-difluorosuccinic acids and their derivatives

• David O'Hagan,
• Henry S. Rzepa,
• Martin Schüler and
• Alexandra M. Z. Slawin

Beilstein J. Org. Chem. 2006, 2, No. 19, doi:10.1186/1860-5397-2-19

• structure is shown in Figure 5. In the X-ray crystal structure of erythro-19 both of the carboxylic acid carbonyl oxygens adopt a syn periplanar conformation with respect to the C-F bonds. In the crystal packing, the carboxylate groups of two neighbouring molecules are hydrogen bonded and this clearly

The first salen- type ligands derived from 3',5'-diamino- 3',5'-dideoxythymidine and -dideoxyxylothymidine and their corresponding copper(II) complexes

• Daniel Koth,
• Michael Gottschaldt,
• Helmar Görls and
• Karolin Pohle

Beilstein J. Org. Chem. 2006, 2, No. 17, doi:10.1186/1860-5397-2-17

• salicylidene imines formed stable coordination compounds with copper(II) ions, which represent the first salen type complexes of nucleosides with this substitution pattern. These complexes tap the full potential of nucleoside derivatives as chiral ligands for transition metal ions. X-ray crystal structure of

A superior P-H phosphonite: Asymmetric allylic substitutions with fenchol- based palladium catalysts

• Bernd Goldfuss,
• Thomas Löschmann,
• Tina Kop-Weiershausen,
• Jörg Neudörfl and
• Frank Rominger

Beilstein J. Org. Chem. 2006, 2, No. 7, doi:10.1186/1860-5397-2-7

• File 1 for full experimental data). All three P, N-bidentate FENOP ligands, FENOP, FENOP-Me and FENOP-NMe2, favor branched alkylation products (Table 1). This tendency towards formation of chiral, branched products is even apparent from X-ray crystal structure analyses of corresponding Pd-phenylallyl

• ligand. X-ray crystal structure of the cationic complex Pd-FENOP (CCDC 299944), the perchlorate counterion and hydrogen atoms are omitted. The allylic phenyl groups is positioned trans to phosphorus. In agreement with the the "trans rule", C3-Pd is longer then C1-Pd. The nucleophile (i.e. malonate) is

• expected to attack at C3 yielding the branched product. Distances are given in Angstroms. X-ray crystal structure of the cationic complex Pd-FENOP-Me (CCDC 600369), the perchlorate counterion and hydrogen atoms are omitted. The allylic phenyl groups is positioned trans to phosphorus. In agreement with the

Trapping evidence for the thermal cyclization of di-(o-acetylphenyl)acetylene to 3,3'-dimethyl- 1,1'-biisobenzofuran

• Charles P. Casey,
• Neil A. Strotman and
• Ilia A. Guzei

Beilstein J. Org. Chem. 2005, 1, No. 18, doi:10.1186/1860-5397-1-18

• the transient production of A, the first biisobenzofuran. An X-ray crystal structure of meso-3 was obtained. As part of a recent study of the thermal cyclization of η2-(o-ethynylbenzoyl)rhenium complexes to rhenium isobenzofuryl carbene complexes (Scheme 1),[1] we attempted to form a rhenium complex

• decomposition process. Here we report evidence for a bicyclization reaction of 1 leading to the first biisobenzofuran, and its trapping by reaction with dimethyl acetylenedicarboxylate (DMAD). An X-ray crystal structure of the resulting bis Diels-Alder adduct of this highly unstable isobenzofuran is reported

• 13C NMR spectroscopy as well as by HRMS. X-ray quality crystals of meso-3 were obtained by slow diffusion of pentane into CH2Cl2 solution. In the X-ray crystal structure, meso-3 adopts a Ci symmetric conformation (Figure 1). Isolation of DMAD adducts meso-3 and rac-3 provides strong evidence for the

An exceptional P-H phosphonite: Biphenyl- 2,2'-bisfenchylchlorophosphite and derived ligands (BIFOPs) in enantioselective copper- catalyzed 1,4-additions

• T. Kop-Weiershausen,
• J. Lex,
• J.-M. Neudörfl and
• B. Goldfuss

Beilstein J. Org. Chem. 2005, 1, No. 6, doi:10.1186/1860-5397-1-6

• the phosphorus atoms in biphenyl-2,2'-bisfenchylphosphites (BIFOPs) founds the special suitability for BIFOP-H (3) as P-H phosphonite ligand in transition metal catalysis. This points to promising applications of 3 or analogue P-H ligands in enantioselective catalysis. X-ray crystal structure of BIFOP