Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

• Louis P. Sandjo,
• Victor Kuete and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2015, 11, 1667–1699, doi:10.3762/bjoc.11.183

• Japp–Klingemann reaction was used to transform the diazonium salt in the presence of ethyl 2-methyl-3-oxobutyrate into the respective hydrazone. The indole was formed from the treatment of the hydrazone with polyphosphoric acid. The last heterocyclic ring was formed by an intramolecular reaction of the

Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

• Awatef Ayadi,
• Aziz El Alamy,
• Olivier Alévêque,
• Magali Allain,
• Nabil Zouari,
• Mohammed Bouachrine and
• Abdelkrim El-Ghayoury

Beilstein J. Org. Chem. 2015, 11, 1379–1391, doi:10.3762/bjoc.11.149

• dinitrophenyl ring coplanar with the hydrazone unit and also by an intramolecular short contact S4···N1 (2.824(6) Å) that makes the TTF unit and the pyridine ring coplanar. In the solid state, the packing arrangement in L1 is characterized by the self-assembly between the TTF donor unit and the dinitrophenyl

• that occurs in ligand L2 leading to a resonance structure that involves the C=N hydrazone bond as it can be seen in (Figure S2, Supporting Information File 1). Theoretical calculations Theoretical calculations based on density functional theory (DFT) methods have been performed with the Gaussian 09

• two reversible oxidations at E1ox = +0.20 V, E2ox = +0.70 V and E1ox = +0.25 V, E2ox = +0.70 V vs Ag/Ag+, respectively) that are cathodically shifted when compared to the ones of 1 and 2 indicating that the pyridine-hydrazone group is less electron deficient than the corresponding

Bifunctional dendrons for multiple carbohydrate presentation via carbonyl chemistry

• Davide Bini,
• Francesco Nicotra and
• Laura Cipolla

Beilstein J. Org. Chem. 2014, 10, 1686–1691, doi:10.3762/bjoc.10.177

• carbonyl groups can be exploited for carbohydrate functionalization [15][16] by reductive amination, oxime or hydrazone formation to yield suitably functionalized saccharides (Figure 1). Given the relevance of L-fucose in mammal oligosaccharides, α-L-(2-aminoethyl) fucoside [17] and α-O-L

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

• -dioxan-5-one as a starting material and employed the SAMP-/RAMP-hydrazone methodology to obtain an overall yield of 18–21% [19][20]. Due to the formation of the opposite configuration at C-4′ and a lengthy synthetic route this strategy is not suitable for the total synthesis of trachycladine A and B

Chemistry of polyhalogenated nitrobutadienes, 14: Efficient synthesis of functionalized (Z)-2-allylidenethiazolidin-4-ones

• Viktor A. Zapol’skii,
• Jan C. Namyslo,
• Mimoza Gjikaj and
• Dieter E. Kaufmann

Beilstein J. Org. Chem. 2014, 10, 1638–1644, doi:10.3762/bjoc.10.170

• intermediate I (SNVin reaction). Thereby, a second equivalent of hydrazine captures hydrochloric acid. The amino group of the hydrazone then attacks the electrophilic C-2 position of the thiazolidinone. This way a threefold substituted 1H-pyrazole is formed (intermediate II) under ring opening of the

The search for new amphiphiles: synthesis of a modular, high-throughput library

• George C. Feast,
• Thomas Lepitre,
• Xavier Mulet,
• Charlotte E. Conn,
• Oliver E. Hutt,
• G. Paul Savage and
• Calum J. Drummond

Beilstein J. Org. Chem. 2014, 10, 1578–1588, doi:10.3762/bjoc.10.163

• , and to deepen the understanding of how molecular structure influences the characteristics of self-assembly. Previous amphiphile libraries have been prepared using a thiol–yne reaction [14] and an in situ hydrazone formation between aldehyde tails and hydrazide head groups [15] in order to study gene

Carbohydrate PEGylation, an approach to improve pharmacological potency

• M. Eugenia Giorgi,
• Rosalía Agusti and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 1433–1444, doi:10.3762/bjoc.10.147

• pharmacokinetic properties than the peptide amino-PEGylated or the unmodified ricin. The same technique was applied to glucose oxidase (GOx), a glycosylated dimeric protein. In this case the hydrazone was further stabilized by reduction with cyanoborohydride to afford a bioconjugate with retention of its activity

Substrate dependent reaction channels of the Wolff–Kishner reduction reaction: A theoretical study

• Shinichi Yamabe,
• Guixiang Zeng,
• Wei Guan and
• Shigeyoshi Sakaki

Beilstein J. Org. Chem. 2014, 10, 259–270, doi:10.3762/bjoc.10.21

• , H2N–NH2 and OH−(H2O)7. Here, ketones are acetone and acetophenone. While routes of the ketone → hydrazone → diimine are similar, those from the diimines are different. From the isopropyl diimine, the N2 extrusion and the C–H bond formation takes place concomitantly. The concomitance leads to the

• . From hydrazone, the hydrazone anion is formed, which was first suggested by Seibert [6][7]. From the anion, there are two routes (a) and (b). In (a), the proton is [1,3]-shifted to give an isomer anion, R1(R2)HC–N=N(−). In (b), a diimine intermediate R1(R2)HC–N=N–H is generated [6][7][8]. Both routes

• lead to a carbanion R1(R2)HC−. Protonation of the carbanion affords the product alkane. It is believed that the hydrazone anion is involved in the rate-determining step of the W-K reaction [9]. W-K reactions of hydrazones in aprotic solvents were investigated. Cram et al. obtained diphenylmethane H2C

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

A simple, enaminone-based approach to some bicyclic pyridazinium tetrafluoroborates

• František Josefík,
• Markéta Svobodová,
• Valerio Bertolasi and
• Petr Šimůnek

Beilstein J. Org. Chem. 2013, 9, 1463–1471, doi:10.3762/bjoc.9.166

• the 2nd step) and could catalyze an intramolecular attack of hydrazone NH nitrogen to the carbonyl group. After a subsequent loss of water, the molecule of pyridazinium salt 5 is formed. This hypothesis is supported by the fact that the use of an excess of sodium acetate led to significantly lower

Dipolar addition to cyclic vinyl sulfones leading to dual conformation tricycles

• Steven S. Y. Wong,
• Michael G. Brant,
• Christopher Barr,
• Allen G. Oliver and
• Jeremy E. Wulff

Beilstein J. Org. Chem. 2013, 9, 1419–1425, doi:10.3762/bjoc.9.159

• hydrazone function should disfavor formation of one of the new C–C bonds in 3. However, we speculate that the increase in electron density serves to disfavor dimerization more than 1,3-dipolar addition to 1a. As a result, more dipole remains in solution to undergo the desired coupling. The effect of this

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

• which the α-substituent on the carbene carbon varies (see below). The α-phenyl analogue of β-lactam 5b has previously been prepared by carbene C–H insertion. In these reports, the base-promoted decomposition of a hydrazone and subsequent thermolysis of the diazo compound in, e.g., toluene under reflux

Camera-enabled techniques for organic synthesis

• Steven V. Ley,
• Richard J. Ingham,
• Matthew O’Brien and
• Duncan L. Browne

Beilstein J. Org. Chem. 2013, 9, 1051–1072, doi:10.3762/bjoc.9.118

Substituent effect on the energy barrier for σ-bond formation from π-single-bonded species, singlet 2,2-dialkoxycyclopentane-1,3-diyls

• Jianhuai Ye,
• Yoshihisa Fujiwara and
• Manabu Abe

Beilstein J. Org. Chem. 2013, 9, 925–933, doi:10.3762/bjoc.9.106

• , CH), 105.90 (d, CH), 133.44 (s, C), 161.54 (s, COCH3); ESIMS (m/z): [M + Na]+ calcd for C18H20O4N4, 379.13768; found, 379.13776. 5,5-Dimethyl-2,2-bis(3,5-dimethoxybenzyl)-Δ3-1,3,4-oxadiazoline (2f). A solution of (3,5-dimethoxybenzyloxycarbonyl)hydrazone of acetone (1.30 g, 4.87 mmol) in CH2Cl2 (5 mL

Recent advances towards azobenzene-based light-driven real-time information-transmitting materials

• Jaume García-Amorós and
• Dolores Velasco

Beilstein J. Org. Chem. 2012, 8, 1003–1017, doi:10.3762/bjoc.8.113

• substitution (type-I), that is, bearing a push–pull configuration. Secondly, kinetic studies of different azophenolic systems (type-II) will be presented, since these azoderivatives exhibit a fast thermal back reaction due to their capability to establish an azo-hydrazone tautomeric equilibrium. Both type-I

• switches acting within the milliseconds time scale, based on chromophores able to establish azo-hydrazone tautomeric equilibria Hydroxy-substituted azobenzenes are a very interesting family of rapidly thermally isomerising azoderivatives, which have been applied successfully not only for light-driven

• molecules control the rate of the isomerisation process for type-II azoderivatives. The formation of intermolecular hydrogen bonds between the nitrogen atom of the azo group and the solvent proton, as well as between the OH group of the azo-dye and the solvent, favours a hydrazone-like electronic

Multistep organic synthesis of modular photosystems

• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2012, 8, 897–904, doi:10.3762/bjoc.8.102

• new method introduced to secure facile access to complex architectures. Chemoorthogonal to the ring-opening disulfide exchange used for SOSIP, hydrazone exchange is then introduced to achieve stack exchange, which is a “switching” technology invented to drill giant holes into SOSIP architectures and

• fill them with functional π-stacks of free choice. Keywords: asparagusic acid; charge-transfer cascades; chromophores; disulfide exchange; hydrazone exchange; molecular switches; naphthalenediimides; π-stacks; surface-initiated polymerization; Introduction The architecture of photosystem 1 is rather

• acid 28. Hydrazide deprotection in NDI 29 and in situ hydrazone formation with benzaldehyde 30 gave propagator 3. In contrast to propagator 3, propagator 4 is constructed around a yellow, core-substituted cNDI fluorophore. Nevertheless, the synthesis of this target molecule also starts with NDA 13

The importance of the rotor in hydrazone-based molecular switches

• Xin Su,
• Timo Lessing and
• Ivan Aprahamian

Beilstein J. Org. Chem. 2012, 8, 872–876, doi:10.3762/bjoc.8.98

• of a series of hydrazone-based systems having different functional groups as part of the rotor (R = COMe, CN, Me, H), was studied. The switching efficiency of these systems was compared to that of a hydrazone-based molecular switch (R = COOEt) whose E/Z isomerization is fully reversible. It was found

• isomerization; hydrazone; molecular switches; pH activation; structure–property analysis; Findings Nature is full of elegant examples of perfectly designed biological motors and machines [1] that perform delicate and precise tasks. Primitive as they may be, numerous artificial molecular machines [2][3][4][5][6

• -based light-driven rotary switches that can be induced to rotate at different rates by replacing a naphthyl group in the upper-half of the molecule (i.e., the rotor) with a less sterically hindered benzothiophenyl group [20]. Previously, we have shown that hydrazone-based rotary switches can change

Chemo-enzymatic modification of poly-N-acetyllactosamine (LacNAc) oligomers and N,N-diacetyllactosamine (LacDiNAc) based on galactose oxidase treatment

• Christiane E. Kupper,
• Ruben R. Rosencrantz,
• Birgit Henßen,
• Helena Pelantová,
• Stephan Thönes,
• Anna Drozdová,
• Vladimir Křen and
• Lothar Elling

Beilstein J. Org. Chem. 2012, 8, 712–725, doi:10.3762/bjoc.8.80

• of 10a showing the potential to produce terminally as well as internally oxidised and modified poly-LacNAc oligomers (11a). A: Labelling of poly-LacNAc oligomers 3a–c and 9a with biotin hydrazide derivative BACH (12) yielding the hydrazone products (13a–c and 14a); 13a–c and 14a were subsequently

Chemistry of polyhalogenated nitrobutadienes, 10: Synthesis of highly functionalized heterocycles with a rigid 6-amino-3-azabicyclo[3.1.0]hexane moiety

• Viktor A. Zapol’skii,
• Jan C. Namyslo,
• Armin de Meijere and
• Dieter E. Kaufmann

Beilstein J. Org. Chem. 2012, 8, 621–628, doi:10.3762/bjoc.8.69

• starting materials for biologically active compounds. Pharmaceuticals bearing an azabicyclo[3.1.0]hexane unit. Stabilizing hydrogen bond in nitrobutadiene-derived imidacloprid analogues 9–12. Conceivable tautomeric structures of 16. Synthesis of the azabicyclic hydrazone 6. Novel imidacloprid analogues 11

Ugi post-condensation copper-triggered oxidative cascade towards pyrazoles

• Aurélie Dos Santos,
• Laurent El Kaim,
• Laurence Grimaud and
• Caroline Ronsseray

Beilstein J. Org. Chem. 2011, 7, 1310–1314, doi:10.3762/bjoc.7.153

• Pyrazolidinones were prepared in a two-step sequence starting from α-hydrazonocarboxylic acids. After a four-component Ugi coupling, the resulting hydrazone was engaged in a copper triggered [3 + 2] cycloaddition/aerobic oxidation cascade. Keywords: aerobic oxidation; copper(II); [3 + 2] cycloaddition; hydrazone

• pyrazolidinone under oxidative conditions from simple hydrazone derivatives (Scheme 1) [13]. The cascade features a [3 + 2] cycloaddition coupled with an aerobic oxidation of the resulting pyrazolidine. A further oxidative coupling may be observed according to the substitution pattern of the starting acyl

• possible Ugi pathways to introduce an alkene moiety that is prone to undergo an intramolecular [3 + 2] cycloaddition with a hydrazone, we selected the Ugi coupling between α-hydrazonocarboxylic acids and allylamine as the most straightforward path. There are several reports on the use of hydrazones in Ugi

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

• indole synthesis a hydrazine, which is most commonly derived from the corresponding diazonium salt, is reacted with a suitable carbonyl compound. Alternatively, the Japp–Klingemann reaction can be used to directly couple the diazonium salt with a β-ketoester to obtain a hydrazone which can then undergo

• intermediate for carvedilol is 4-hydroxy-9H-carbazole (141) [42]. In analogy to the Fischer indole synthesis, cyclohexane-1,3-dione monophenyl hydrazone 139 is prepared via condensation of phenylhydrazine (138) with 1,3-cyclohexanedione (121, Scheme 29). This compound can then undergo an acid catalysed Fischer

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• reaction of trifluoroacetylbenzyl cyanide 4 with heteroarylhydrazines [32]. The reaction of 2-hydrazino-4-methylquinoline with α-trifluoroacetylbenzyl cyanide (R = CF3) (4) at room temperature afforded the intermediate hydrazone 5. The hydrazone 5 was characterized by IR and NMR spectroscopy. The IR

• spectrum of 5 showed a fundamental stretching band due to C≡N at 2179 cm−1. The 19F NMR spectrum of compound 5 showed fluorine signal at δ −65 ppm due to CF3 group confirming the formation of hydrazone 5, which exists as the Z-isomer. From the literature [33], the signal for the CF3 group in

• -oxotetrahydrothiophene (18) in refluxing ethanol gave the thienopyrazoles in excellent yields. The regioselectivity of this process has been confirmed by the treatment of 18 with phenylhydrazine, which generated a mixture of intermediate hydrazone 20 and 2-phenyl-3-aminothieno[3,4-c]pyrazole (21) (Scheme 6). Hydrazones

Synthesis of some novel hydrazono acyclic nucleoside analogues

• Mohammad N. Soltani Rad,
• Ali Khalafi-Nezhad and
• Somayeh Behrouz

Beilstein J. Org. Chem. 2010, 6, No. 49, doi:10.3762/bjoc.6.49

• Abstract The syntheses of novel hydrazono acyclic nucleosides similar to miconazole scaffolds are described. In this series of acyclic nucleosides, pyrimidine as well as purine and other azole derivatives replaced the imidazole function in miconazole and the ether group was replaced with a hydrazone moiety

• using phenylhydrazine. To interpret the dominant formation of (E)-hydrazone derivatives rather than (Z)-isomers, PM3 semiempirical quantum mechanic calculations were carried out which indicated that the (E)-isomers had the lower heats of formation. Keywords: acyclic nucleoside; chemotherapeutic agent

• ; hydrazone; ketone; miconazole; Introduction In recent years, fungal infections have become an important complication and a major cause of morbidity and mortality in immune-compromised individuals who suffer from tuberculosis, cancer or AIDS, and who undergo organ transplants [1][2]. Up to now, there has

Synthesis of thienyl analogues of PCBM and investigation of morphology of mixtures in P3HT

• Fukashi Matsumoto,
• Kazuyuki Moriwaki,
• Yuko Takao and
• Toshinobu Ohno

Beilstein J. Org. Chem. 2008, 4, No. 33, doi:10.3762/bjoc.4.33

• chloroform as an eluent and the compounds 1a and 1b were easily obtained. Then, the carbonyl group of 1 was converted to hydrazone by mixing 1 with p-toluenesulfonyl hydrazide. The compounds 2 were obtained as white to pale yellow solids in good yields (2a; 85%, 2b; 90%, 2c; 74%, 2d; 70%). The

• shifts of bridging units. It is well known that [5,6]fulleroid has low solubility and is thermodynamically unstable; hence, it cannot be used in a photovoltaic device. However, except for 2b, the thienyl-substituted hydrazones 2a, 2c, and 2d yielded only [6,6]methanofullerenes. The hydrazone 2b yielded a

One-pot synthesis of novel 1H-pyrimido[4,5-c][1,2]diazepines and pyrazolo[3,4-d]pyrimidines

• Dipak Prajapati,
• Partha P. Baruah,
• Baikuntha J. Gogoi and
• Jagir S. Sandhu

Beilstein J. Org. Chem. 2006, 2, No. 5, doi:10.1186/1860-5397-2-5

• hot acid produces pyrazolo [3,4-d]pyrimidines, most likely by hydrolytic ring opening at the 'hydrazone' bond followed by a retro-aldol reaction and ring closure.[25][33][34] In contrast, we synthesised the corresponding pyrazolo [3,4-d]pyrimidines in high yields under mild conditions without heating