Ring opening metathesis polymerization-derived block copolymers bearing chelating ligands: synthesis, metal immobilization and use in hydroformylation under micellar conditions

• Gajanan M. Pawar,
• Jochen Weckesser,
• Siegfried Blechert and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2010, 6, No. 28, doi:10.3762/bjoc.6.28

• , MBraun). Benzene, n-hexane and dimethoxyethane (DME) were dried and distilled from sodium/benzophenone ketyl under argon. NMR spectra were recorded at room temperature on a Bruker AM 400 (400 MHz for proton and 100.6 MHz for carbon) and on a Bruker Avence 600 II+ (600.25 MHz for proton and 150.93 MHz for

Synthesis and binding studies of two new macrocyclic receptors for the stereoselective recognition of dipeptides

• Ana Maria Castilla,
• M. Morgan Conn and
• Pablo Ballester

Beilstein J. Org. Chem. 2010, 6, No. 5, doi:10.3762/bjoc.6.5

• benzophenone unit would be ideally suited to span the gap between two methyl side chains emerging from alanyl residues of the outer strands in the three-stranded β-sheet complex (Figure 1). In proteins, adjacent β-strands can form hydrogen bonds in antiparallel, parallel, or mixed arrangements. In an

• macrocycle, also allows for the possibility of binding short amino acid sequences not necessarily located on the edges of larger peptides. Other considerations, apart from preventing intramolecular hydrogen bond formation, related to the use of bis(alanyl)benzophenone rigid linkers include: a) to avoid

• steric clashes between the methyl groups of the target peptide and the benzophenone linking chains, the stereogenic centers in the linkers must have the (S) configuration, opposite to that of the bound peptide (R); b) the benzophenone aromatic ring will also provide a hydrophobic pocket for the

Synthesis of unsymmetrically substituted biaryls via sequential lithiation of dibromobiaryls using integrated microflow systems

• Aiichiro Nagaki,
• Naofumi Takabayashi,
• Yutaka Tomida and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2009, 5, No. 16, doi:10.3762/bjoc.5.16

• iodomethane gave 2-bromo-2′-methylbiphenyl (5) in 89% yield with high selectivity. Chlorotrimethylsilane, benzaldehyde, and benzophenone were also effective as electrophiles, and the corresponding products derived from the monolithiated species were obtained selectively in high yields. These results show that

• the optimized reaction conditions (reaction temperature: 0 °C, tR: 0.057 s), reactions using other electrophiles (0.30 M in THF) such as iodomethane, benzaldehyde, and benzophenone were examined to obtain the corresponding products in good yields at 0 °C as shown in Table 6. These results show that

Enantiospecific synthesis of [2.2]paracyclophane- 4-thiol and derivatives

• Gareth J. Rowlands and
• Richard J. Seacome

Beilstein J. Org. Chem. 2009, 5, No. 9, doi:10.3762/bjoc.5.9

• ethanolic vanillin, aqueous potassium manganate(VII), ninhydrin or acidic anisaldehyde as appropriate. Petrol refers to redistilled petroleum ether (60–80 °C), and ether to diethyl ether. Ether and THF were distilled from sodium-benzophenone ketyl, toluene from 4Å molecular sieves or calcium chloride

Quinoline based receptor in fluorometric discrimination of carboxylic acids

• Kumaresh Ghosh,
• Suman Adhikari,
• Asoke P. Chattopadhyay and
• Purnendu Roy Chowdhury

Beilstein J. Org. Chem. 2008, 4, No. 52, doi:10.3762/bjoc.4.52

• binding and selection of the guest carboxylic acids. Experimental General details. All reactions were carried out under a nitrogen atmosphere. Solvents were dried before use. Solvents for spectroscopic measurements were of spectroscopic or HPLC grade. THF was freshly distilled from sodium benzophenone

The use of chiral lithium amides in the desymmetrisation of N-trialkylsilyl dimethyl sulfoximines

• Matthew J. McGrath and
• Carsten Bolm

Beilstein J. Org. Chem. 2007, 3, No. 33, doi:10.1186/1860-5397-3-33

• in 61% and 69% yield, respectively, thus furnishing substrates for deprotonation reactions. Initial attempts at enantioselective deprotonation of TMS protected 1a using a complex of (-)-sparteine 4 (Figure 1) and n-BuLi as the chiral base and trapping the resulting anion with benzophenone gave the

• deprotonation temperature to -94°C (MeOH-liquid nitrogen bath) gave silyl adduct 2b in 54% ee (Table 1, Entry 6), a further decrease in temperature to -105°C gave the desired adduct in 61% ee and 58% yield (Table 1, Entry 7). Use of lithium amide 6 with benzophenone as electrophile led to adduct 2c of only 38

• % ee (Table 1, Entry 8) and reactions with lithium diamide 7 gave silyl derivative 2b in good yield but with no detecenantiomeric excess (Table 1, Entry 9). Various electrophiles were tested in the desymmetrisation reaction using lithium amide 5. Benzophenone proved to be superior to TMSCl (Table 2

Microwave assisted synthesis of triazoloquinazolinones and benzimidazoquinazolinones

• Aboul-Fetouh E. Mourad,
• Ashraf A. Aly,
• Hassan H. Farag and
• Eman A. Beshr

Beilstein J. Org. Chem. 2007, 3, No. 11, doi:10.1186/1860-5397-3-11

• compounds with 2-ethoxymethyleneaminonitriles. [9] A general route to prepare 5,10-dihydro-[1,2,4]-triazolo-[5,1-b]-quinazolines included the reaction of benzophenone and 1-ureidoethylidene-hydrazones with a mixture of triphenylphosphine, carbon tetrachloride, and triethylamine in dichloromethane. [10