Scalable synthesis of (1-cyclopropyl)cyclopropylamine hydrochloride

• Sergei I. Kozhushkov,
• Alexander F. Khlebnikov,
• Rafael R. Kostikov,
• Dmitrii S. Yufit and
• Armin de Meijere

Beilstein J. Org. Chem. 2011, 7, 1003–1006, doi:10.3762/bjoc.7.113

• obtained according to the previously published procedure [21]. A 5.0 N solution of HCl in Et2O was prepared by saturation of anhydrous Et2O with gaseous HCl at 0 °C. Anhydrous diethyl ether was obtained by distillation from sodium benzophenone ketyl, acetone by distillation from anhydrous potassium

The arene–alkene photocycloaddition

• Ursula Streit and
• Christian G. Bochet

Beilstein J. Org. Chem. 2011, 7, 525–542, doi:10.3762/bjoc.7.61

• that the meta photocycloaddition occurs from the singlet excited-state; they observed that 6-phenyl-2-hexene undergoes cis–trans isomerization upon sensitizing with acetone and benzophenone, whereas the photocycloaddition to the meta product could only be triggered via direct irradiation [23]. Mode

• can take place to form a spiro compound; further re-aromatization to form the enol, lactolization and cyclization explains the formation of the benzoxepine structure [101]. Griesbeck et al. reported the formation of benzoxepines from the benzophenone analogue upon irradiation at slightly lower

Photoinduced electron-transfer chemistry of the bielectrophoric N-phthaloyl derivatives of the amino acids tyrosine, histidine and tryptophan

• Axel G. Griesbeck,
• Jörg Neudörfl and
• Alan de Kiff

Beilstein J. Org. Chem. 2011, 7, 518–524, doi:10.3762/bjoc.7.60

• and ФISC < 0.01 for N-arylphthalimides [1]. If necessary, the population of the triplet state is also possible by sensitization, e.g., with triplet sensitizers such as acetone or benzophenone. With a triplet energy ET of 293–300 kJ mol−1 and a ground-state reduction potential E0 of −1.85 V vs Fc/Fc

• temperature and in ethanol at low temperatures are known: Triplet acetone, acetophenone and xanthone in acetonitrile are quenched by 1 via energy transfer; the rate constant is almost diffusion-controlled and somewhat smaller for benzophenone. The sole product from the photolysis of 1 is the double hydrogen

• measured for a series of bichromophoric systems based on phthalimide–linker–donor triades [12]. Concerning the photochemistry of 10, a remarkable difference to all other phthalimide derivatives occurred: Neither direct excitation nor triplet (acetone, benzophenone) sensitized conditions led to substrate

Synthesis of 5-(2-methoxy-1-naphthyl)- and 5-[2-(methoxymethyl)-1-naphthyl]-11H-benzo[b]fluorene as 2,2'-disubstituted 1,1'-binaphthyls via benzannulated enyne–allenes

• Yu-Hsuan Wang,
• Joshua F. Bailey,
• Jeffrey L. Petersen and
• Kung K. Wang

Beilstein J. Org. Chem. 2011, 7, 496–502, doi:10.3762/bjoc.7.58

• nitrogen atmosphere. Diethyl ether and tetrahydrofuran (THF) were distilled from benzophenone ketyl prior to use. 1-Ethynyl-2-methoxybenzene (4a), pivalophenone (7), n-butyllithium (1.6 M) in hexanes, 1-bromo-2-[2-(trimethylsilyl)ethynyl]benzene, triethylsilane, trifluoroacetic acid, potassium tert

Effects of anion complexation on the photoreactivity of bisureido- and bisthioureido-substituted dibenzobarrelene derivatives

• Heiko Ihmels and
• Jia Luo

Beilstein J. Org. Chem. 2011, 7, 278–289, doi:10.3762/bjoc.7.37

• benzophenone, a triplet-state di-π-methane rearrangement is induced. Thus, in the initial reaction step connection between one vinyl and one benzo carbon atom takes place, i.e., a so called vinyl–benzo bridging, that leads to the intermediate biradical BR1a [29]. Subsequent rearomatization with the formation

Formation of macrocyclic lactones in the Paternò–Büchi dimerization reaction

• Junya Arimura,
• Tsutomu Mizuta,
• Yoshikazu Hiraga and
• Manabu Abe

Beilstein J. Org. Chem. 2011, 7, 265–269, doi:10.3762/bjoc.7.35

• synthetically useful four-membered heterocyclic compounds, i.e., oxetanes. The Paternò–Büchi reaction of furan with a triplet carbonyl, such as n,π* triplet benzophenone, produces regioselectively 2-alkoxyoxetanes 2OX (Scheme 1). The regioselective formation is rationalized by the relative stability of the

Synthesis of cationic dibenzosemibullvalene-based phase-transfer catalysts by di-π-methane rearrangements of pyrrolinium-annelated dibenzobarrelene derivatives

• Heiko Ihmels and
• Jia Luo

Beilstein J. Org. Chem. 2011, 7, 119–126, doi:10.3762/bjoc.7.17

• ], undergo a photo-induced di-π-methane rearrangement upon triplet sensitization to give the corresponding cationic dibenzosemibullvalene derivatives [N,N-dialkyl-3,4-{8c,8e-(4b,8b-dihydrodibenzo[a,f]cyclopropa[cd]pentaleno)}pyrrolidinium derivatives]. Whereas the covalent attachment of a benzophenone

• functionality to the pyrrolinium nitrogen atom did not result in an internal triplet sensitization, the introduction of a benzophenone unit as part of the counter ion enables the di-π-methane rearrangement of the dibenzobarrelene derivative in the solid-state. Preliminary experiments indicate that a cationic

• presence of an appropriate sensitizer, such as acetone or benzophenone, dibenzobarrelene (DBB) rearranges to dibenzosemibullvalene (DBS), whereas the direct excitation leads to dibenzocyclooctene (DBC) through the singlet excited-state (Scheme 1) [4][5][7]. The DPM photorearrangement of dibenzobarrelene

Heavy atom effects in the Paternò–Büchi reaction of pyrimidine derivatives with 4,4’-disubstituted benzophenones

• Feng-Feng Kong,
• Jian-Bo Wang and
• Qin-Hua Song

Beilstein J. Org. Chem. 2011, 7, 113–118, doi:10.3762/bjoc.7.16

• (DMT) and 1,3-dimethyluracil (DMU) with benzophenone (1b) and some 4,4’-disubstituted derivatives (dimethoxy (1a), difluoro (1c), dichloro (1d), dibromo (1e) and dicyano benzophenone (1f)) that gives rise to two regioisomeric oxetanes, 2 and 3. The regioselectivity (the ratio of 2/3) decreased

• 1c) is enthalpy–entropy controlled. A heavy atom effect is suggested to be responsible for these unusual phenomena based on the triplet-diradical mechanism of the Paternò–Büchi reaction. Keywords: benzophenone; heavy atom effect; Paternò–Büchi reaction; regioselectivity; triplet diradical

• detected for the reaction of α-deuterated propionaldehyde [15]. In this work, we have investigated the Paternò–Büchi reaction of 1,3-dimethylthymine (DMT) and 1,3-dimethyluracil (DMU) with benzophenone (1b) and its 4,4’-disubstituted derivatives 1a and 1c–1f with the formation of the regioisomeric oxetanes

Donor-acceptor substituted phenylethynyltriphenylenes – excited state intramolecular charge transfer, solvatochromic absorption and fluorescence emission

• Ritesh Nandy and
• Sethuraman Sankararaman

Beilstein J. Org. Chem. 2010, 6, 992–1001, doi:10.3762/bjoc.6.112

• transfer from the aromatic moiety to the benzophenone has been previously shown by time resolved spectroscopy to result in the formation of a radical ion pair [52][53][54]. HOMO and LUMO surfaces and energy gaps Cyclic voltammograms of 1a–e and 1g were recorded in acetonitrile in order to obtain the redox

• ; ESI Q-TOF MS m/z 371 [M + H]+; HRMS calcd for C28H19O [M + H]+ 371.1436; found, 371.1433. 4-(2-Triphenylenylethynyl)benzophenone (1e). The crude product was purified by column chromatography with a mixture of hexane and dichloromethane (80:20, v/v) as eluant to yield 1e as a colorless solid (0.517 g

En route to photoaffinity labeling of the bacterial lectin FimH

• Thisbe K. Lindhorst,
• Michaela Märten,
• Andreas Fuchs and
• Stefan D. Knight

Beilstein J. Org. Chem. 2010, 6, 810–822, doi:10.3762/bjoc.6.91

• of the benzophenone 3, on the other hand, delivers a reactive triplet diradical. In addition, in order to combine a photoactive functional group with an affinity label within the same mannoside, the orthogonally protected glycoamino acid scaffold 4 was synthesized and used for the preparation of the

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• anilines but also for N-monosubstituted substrates and even those with a free NH2 group (Scheme 11). In naphthalene and benzophenone derivatives only those rings containing hydroxy or amino groups undergo perfluoroalkylsulfanylation [74][75]. Other electron-donating substituents on the aromatic ring are

Synthesis of the fluorescent amino acid rac-(7-hydroxycoumarin-4-yl)ethylglycine

• Manfred Braun and
• Torsten Dittrich

Beilstein J. Org. Chem. 2010, 6, No. 69, doi:10.3762/bjoc.6.69

• , alkylation of a glycine enolate with the primary bromide 5 was anticipated. Indeed, its use as the electrophilic component in the coupling with the benzophenone-derived imine of tert-butyl glycine 6, which functioned, after deprotonation, as a synthetic equivalent of a glycine enolate synthon, led to the

• by using Merck TLC Silicagel 60F254 aluminium sheets. Tetrahydrofuran (THF) was freshly distilled from sodium/benzophenone under a nitrogen atmosphere, and dichloromethane was freshly distilled from calcium hydride. 7-Hydroxy-4-(2-hydroxyethyl)-2H-chromen-2-one (3): A 500 mL flask was equipped with a

Poly(glycolide) multi-arm star polymers: Improved solubility via limited arm length

• Florian K. Wolf,
• Anna M. Fischer and
• Holger Frey

Beilstein J. Org. Chem. 2010, 6, No. 67, doi:10.3762/bjoc.6.67

• purified by vacuum distillation over CaH2 directly prior to use. Tetrahydrofuran (THF) was refluxed with sodium/benzophenone before distillation. Glycolide was purchased from Purac®/Gorinchem (Netherlands) and used as received. Tin(II)-2-ethylhexanoate (Sn(Oct)2), 97% was obtained from Acros and used as

Synthesis and crystallographic analysis of meso-2,3-difluoro-1,4-butanediol and meso-1,4-dibenzyloxy-2,3-difluorobutane

• Bruno Linclau,
• Leo Leung,
• Jean Nonnenmacher and
• Graham Tizzard

Beilstein J. Org. Chem. 2010, 6, No. 62, doi:10.3762/bjoc.6.62

• or anisaldehyde stains. Reaction solvents were dried before use as follows: THF and Et2O were distilled from sodium/benzophenone; CH2Cl2 and Et3N were distilled from CaH2; toluene was distilled from sodium. X-ray data crystal structure analyses: Suitable crystals were selected and data collected on a

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