Boron-substituted 1,3-dienes and heterodienes as key elements in multicomponent processes

• Ludovic Eberlin,
• Fabien Tripoteau,
• François Carreaux,
• Andrew Whiting and
• Bertrand Carboni

Beilstein J. Org. Chem. 2014, 10, 237–250, doi:10.3762/bjoc.10.19

• proved to give the best yields, probably due to the higher reactivity of the corresponding hydrazones. Furthermore, the double bond of 29 was selectively hydrogenated under palladium on charcoal, while hydrogenolysis of the hydrazine moiety occurred in the presence of Raney nickel (Scheme 22). Following

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

• (Table 1, entry 10), without traces of the corresponding α-aminoamide. Different types of activated substrates displaying C=N bonds (N-sulfinylimines, oximes and hydrazones) were studied, but none of them reacted productively with isocyanides under the described conditions. Finally, the reaction with

IBD-mediated oxidative cyclization of pyrimidinylhydrazones and concurrent Dimroth rearrangement: Synthesis of [1,2,4]triazolo[1,5-c]pyrimidine derivatives

• Caifei Tang,
• Zhiming Li and
• Quanrui Wang

Beilstein J. Org. Chem. 2013, 9, 2629–2634, doi:10.3762/bjoc.9.298

• derivatives 5a–o. These incipient products undergo feasible Dimroth rearrangement to furnish the isolated [1,2,4]triazolo[1,5-c]pyrimidines 6a–o in moderate to high yields. Keywords: cyclization; hydrazones; hypervalent iodine; oxidation; rearrangement; [1,2,4]triazolo[1,5-c]pyrimidines; Introduction The

• ]pyrimidines by the oxidative cyclisation of benzothieno[2,3-d]pyrimidine hydrazones. The investigation has also suggested the important ability as inhibitors of Shiga toxin trafficking for protecting HeLa cells [9]. The wide range of biological activities shown by various triazolopyrimidines encouraged

• derivatives as the one-carbon cyclizing agent [12] and the dehydrative cyclization of carboxylic acid N'-(pyrimidin-4-yl)-hydrazide and ring rearrangement [13]. Recently, Thiel and coworkers have also established an efficient palladium-catalyzed intermolecular coupling of aldehyde-derived hydrazones with

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• [87]. The mechanism is related to those described above for pivanilides (C. Chen, C. Xi et al.) or hydrazones (D. Bouyssi, O. Baudoin et al.) (Figure 8). 3.2.3 Perfluoroalkylation of Csp2–H bonds by means of a CF3-radical source. Clearly Togni’s electrophilic reagent is able to generate the CF3

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 later giving better yields and applicability (Scheme 1, top). It extends the existing procedure [16][17][18][19][20][21][22][23][24] for the construction of the 1-arylpyridazinium scaffold based on acid- or base-catalyzed cyclization of the corresponding hydrazones (Scheme 1, bottom). Apart from

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

• of this device was for the preparation of a series of hydrazones. A continuous aqueous extraction to remove the excess hydrazine enabled the product to be collected in high purity (Figure 29). Other applications reported in this work include alkene epoxidation and dithiane preparation. Dispersion of

Organocatalytic cascade aza-Michael/hemiacetal reaction between disubstituted hydrazines and α,β-unsaturated aldehydes: Highly diastereo- and enantioselective synthesis of pyrazolidine derivatives

• Zhi-Cong Geng,
• Jian Chen,
• Ning Li,
• Xiao-Fei Huang,
• Yong Zhang,
• Ya-Wen Zhang and
• Xing-Wang Wang

Beilstein J. Org. Chem. 2012, 8, 1710–1720, doi:10.3762/bjoc.8.195

• ], and moreover, pyrazolidines can also be oxidized to afford pyrazolines [8][9][10][11][12] and pyrazoles [13][14][15]. The pyrazolidine structural unit is commonly constructed by [3 + 2] cycloaddition reactions using hydrazones [16][17][18][19][20][21][22][23] or azomethine amines [24][25][26][27] as

• explored by several groups [72][73]. In 2007, Jørgensen et al. reported that the organocatalyzed asymmetric aza-Michael addition of hydrazones to cyclic enones had been achieved in good yield and stereoselectivity [74]. In 2011, the Deng group developed a highly enantioselective organocatalytic synthesis

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

• capture of the red cNDI aldehyde 5. Stack exchange was easily detectable by comparison of the respective maxima in the absorption spectra. Exchange of the benzaldehyde hydrazones in photosystem 51 with NDIs occurred with an excellent 75–95% yield. Moreover, the yield of stack exchange was nearly

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

• properties of the hydrazone switches, we studied the effect of different R groups in the rotor part (Scheme 2) on the switching cycle. The target hydrazones were synthesized either by the direct condensation of phenylhydrazine with the corresponding aldehyde (PPH-2) or ketone (PPH-3), or by Japp–Klingemann

• reaction (PPH-4, PPH-5) [26]. The NMR spectroscopy and mass spectrometry characterizations show results consistent with the previously reported data [26]. In certain cases it has been shown that intramolecularly H-bonded hydrazones exist predominantly as the kinetically stable Z isomer in solution [27][28

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

• derivative 6 in 80% isolated yield (Scheme 1). The interest in such compounds derives from the fact that a number of similar hydrazones, e.g., phenyl(phenylchloromethylidene)hydrazine, exhibit fungicidal, antibacterial, and fungistatic activity [17][18]. In view of the insecticidal properties of some

N-Heterocyclic carbene/Brønsted acid cooperative catalysis as a powerful tool in organic synthesis

• Rob De Vreese and
• Matthias D’hooghe

Beilstein J. Org. Chem. 2012, 8, 398–402, doi:10.3762/bjoc.8.43

• the search for suitable combinations and, if one of both partners is chiral, the development of enantioselective catalytic processes. Selected examples of the successful deployment of cooperative catalysis in organic synthesis comprise the preparation of chiral γ-lactams from N-acyl hydrazones and α,β

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

• 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

• uptake of oxygen helps to control the selective oxidation process. Reactions performed under air were faster but led to intractable mixtures. Analogous hydrazones prepared from pyruvic acid and benzoylformic acid with hydrazine derivatives were tested in this Ugi/oxidative cyclization sequence under

• following cyclization failed to give the expected pyrazolidinones and resulted in complex mixture formation. Intermediate Ugi adduct 3g (Table 1, entry 6) only resulted in a small amount of ring-opened product 4g. The reaction is also limited to N-aryl hydrazones due to the lower efficiency of the Ugi

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

• hydrazines to yield 5-aminopyrazoles 3 [19][20][21][22][23][24][25][26][27][28]. The reaction apparently involves the nucleophilic attack of the terminal nitrogen of the hydrazine on the carbonyl carbon with the formation of hydrazones 2, which subsequently undergo cyclization by the attack of the other

• nitrogen on the nitrile carbon to produce 5-aminopyrazoles 3 (Scheme 1). Utilizing this reaction, a large number of 5-amino-1-heteroarylpyrazoles have been synthesized in our laboratory by the reaction of several heteroarylhydrazines with α-cyanoacetophenones [29][30]. The intermediate hydrazones 2 are

• yielded the corresponding 5-amino-4-phenylpyrazoles 6. These compounds were found to be good antibacterial agents (Scheme 2) [34]. The isolation of hydrazones 8 has also been reported during the condensation of cyanoacetaldehyde (7) with hydrazines [35]. These hydrazones 8 were cyclized to the

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

• ). Pharmacokinetic properties and cellular permeability of a drug can be modulated by derivatization to bio-reversible forms of the drug, namely hydrazones [3]. Hydrazone derivatives are prominent structural motifs in numerous pharmaceutically active compounds. Many well known drugs with various clinical activities

• antineoplastic (e.g. bisantrene [4][10]), contain a hydrazone moiety in their structure. Furthermore, various structurally related miconazole bioactive hydrazones are known as antimicrobial and antifungal agents [11][12]. The significance of nucleoside chemistry in drug discovery is well-known and fully

• synthesized hydrazones 2a–2o using PM3. Supporting Information Supporting information features physical and spectroscopic data for all novel compounds 2a–2o. Supporting Information File 84: Synthesis of some novel hydrazono acyclic nucleoside analogues Acknowledgements We thank the Shiraz University of

New diarylmethanofullerene derivatives and their properties for organic thin- film solar cells

• Daisuke Sukeguchi,
• Surya Prakash Singh,
• Mamidi Ramesh Reddy,
• Hideyuki Yoshiyama,
• Rakesh A. Afre,
• Yasuhiko Hayashi,
• Hiroki Inukai,
• Tetsuo Soga,
• Shuichi Nakamura,
• Norio Shibata and
• Takeshi Toru

Beilstein J. Org. Chem. 2009, 5, No. 7, doi:10.3762/bjoc.5.7

• in the presence of anhydrous AlCl3 gave the carbonyl compounds 15a–k which were treated with p-toluenesulfonylhydrazine to afford the hydrazones 16a–k. Treatment of 16a–k with sodium methoxide or LiHMDS in o-dichlorobenzene (ODCB) gave a mixture of isomeric diarylmethanofullerenes. After purification

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

• 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

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