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Beilstein Journal of Organic Chemistry

Lena Huck, Juan F González, Elena de la Cuesta, J Carlos Menéndez
A sequential three-component process is described, starting from 3-arylmethylene-2,5-piperazinediones and involving a one-pot sequence of reactions achieving regioselective opening of the 2,5-diketopiperazine ring and diastereoselective generation of an aziridine ring. This method allows the preparation of N-unprotected, trisubstituted aziridines bearing a peptide side chain under mild conditions. Their transformation into β-trifluoroacetamido-α-ketoamide and α,β-diketoamide frameworks was also achieved in a single step...
2016: Beilstein Journal of Organic Chemistry
Pramod R Markad, Navanath Kumbhar, Dilip D Dhavale
The C8'-epimeric pyranosyl amino acid core 2 of amipurimycin was synthesized from D-glucose derived alcohol 3 in 13 steps and 14% overall yield. Thus, the Sharpless asymmetric epoxidation of allyl alcohol 7 followed by trimethyl borate mediated regio-selective oxirane ring opening with azide, afforded azido diol 10. The acid-catalyzed 1,2-acetonide ring opening in 10 concomitantly led to the formation of the pyranose ring skeleton to give 2,7-dioxabicyclo[3.2.1]octane 12. Functional group manipulation in 12 gave 21 that on stereoselective β-glycosylation afforded the pyranosyl thymine nucleoside 2 - a core of amipurimycin...
2016: Beilstein Journal of Organic Chemistry
Mei-Yuan Hsu, Yi-Pei Liu, Sarah Lam, Su-Ching Lin, Cheng-Chung Wang
The thio-additions of glycals were efficiently promoted by a stoichiometric amount of trimethylsilyl bromide (TMSBr) to produce S-2-deoxyglycosides under solvent-free conditions in good to excellent yields. In addition, with triphenylphosphine oxide as an additive, the TMSBr-mediated direct glycosylations of glycals with a large range of alcohols were highly α-selective.
2016: Beilstein Journal of Organic Chemistry
Rahman Hosseinzadeh, Mohammad Nemati, Reza Zadmard, Maryam Mohadjerani
Functionalization of calix[4]arene with amidofluorene moieties at the lower rim led to formation of the 1,3-diconjugate of calix[4]arene L as a novel fluorescent chemosensor for Cu(2+). The receptor molecule L exhibited a pronounced selectivity towards Cu(2+) over other mono and divalent ions. The formation of the complex between L and Cu(2+) was evaluated by absorption, fluorescence and (1)H NMR spectroscopy. The sensor L showed a remarkable color change from colorless to purple and a fluorescence quenching only upon interaction with Cu(2+)...
2016: Beilstein Journal of Organic Chemistry
Ivan A Yaremenko, Vera A Vil', Dmitry V Demchuk, Alexander O Terent'ev
This review is the first to collate and summarize main data on named and unnamed rearrangement reactions of peroxides. It should be noted, that in the chemistry of peroxides two types of processes are considered under the term rearrangements. These are conventional rearrangements occurring with the retention of the molecular weight and transformations of one of the peroxide moieties after O-O-bond cleavage. Detailed information about the Baeyer-Villiger, Criegee, Hock, Kornblum-DeLaMare, Dakin, Elbs, Schenck, Smith, Wieland, and Story reactions is given...
2016: Beilstein Journal of Organic Chemistry
Vincent M Rotello
The atom-by-atom control provided by synthetic organic chemistry presents a means of generating new functional nanomaterials with great precision. Bringing together these two very disparate skill sets is, however, quite uncommon. This autobiographical review provides some insight into how my program evolved, as well as giving some idea of where we are going.
2016: Beilstein Journal of Organic Chemistry
Desta Gedefaw, Marta Tessarolo, Margherita Bolognesi, Mario Prosa, Renee Kroon, Wenliu Zhuang, Patrik Henriksson, Kim Bini, Ergang Wang, Michele Muccini, Mirko Seri, Mats R Andersson
Two high bandgap benzodithiophene-benzotriazole-based polymers were synthesized via palladium-catalysed Stille coupling reaction. In order to compare the effect of the side chains on the opto-electronic and photovoltaic properties of the resulting polymers, the benzodithiophene monomers were substituted with either octylthienyl (PTzBDT-1) or dihexylthienyl (PTzBDT-2) as side groups, while the benzotriazole unit was maintained unaltered. The optical characterization, both in solution and thin-film, indicated that PTzBDT-1 has a red-shifted optical absorption compared to PTzBDT-2, likely due to a more planar conformation of the polymer backbone promoted by the lower content of alkyl side chains...
2016: Beilstein Journal of Organic Chemistry
Atul A Dhavan, Rahul D Kaduskar, Loana Musso, Leonardo Scaglioni, Piera Anna Martino, Sabrina Dallavalle
The first total synthesis of leopolic acid A, a fungal metabolite with a rare 2,3-pyrrolidinedione nucleus linked to an ureido dipeptide, was designed and carried out. Crucial steps for the strategy include a Dieckmann cyclization to obtain the 2,3-pyrrolidinedione ring and a Wittig olefination to install the polymethylene chain. An oxazolidinone-containing leopolic acid A analogue was also synthesized. The antibacterial activity showed by both compounds suggests that they could be considered as promising candidates for future developments...
2016: Beilstein Journal of Organic Chemistry
Valeria Corne, Ariel M Sarotti, Carmen Ramirez de Arellano, Rolando A Spanevello, Alejandra G Suárez
Chiral acrylic esters derived from biomass were developed as models to have a better insight in the aryl-vinyl π-stacking interactions. Quantum chemical calculations, NMR studies and experimental evidences demonstrated the presence of equilibriums of at least four different conformations: π-stacked and face-to-edge, each of them in an s-cis/s-trans conformation. The results show that the stabilization produced by the π-π interaction makes the π-stacked conformation predominant in solution and this stabilization is slightly affected by the electron density of the aromatic counterpart...
2016: Beilstein Journal of Organic Chemistry
Motoyuki Isoda, Kazuyuki Sato, Yurika Kunugi, Satsuki Tokonishi, Atsushi Tarui, Masaaki Omote, Hideki Minami, Akira Ando
An effective synthesis for syn-β-lactams was achieved using a Rh-catalyzed reductive Mannich-type reaction. A rhodium-hydride complex (Rh-H) derived from diethylzinc (Et2Zn) and a Rh catalyst was used for the 1,4-reduction of an α,β-unsaturated ester to give a Reformatsky-type reagent, which in turn, reacted with an imine to give the syn-β-lactam. Additionally, the reaction was applied to the synthesis of (±)-ezetimibe, a potent β-lactamic cholesterol absorption inhibitor.
2016: Beilstein Journal of Organic Chemistry
Carl J Mallia, Paul M Burton, Alexander M R Smith, Gary C Walter, Ian R Baxendale
A flow system to perform Chan-Lam coupling reactions of various amines and arylboronic acids has been realised employing molecular oxygen as an oxidant for the re-oxidation of the copper catalyst enabling a catalytic process. A tube-in-tube gas reactor has been used to simplify the delivery of the oxygen accelerating the optimisation phase and allowing easy access to elevated pressures. A small exemplification library of heteroaromatic products has been prepared and the process has been shown to be robust over extended reaction times...
2016: Beilstein Journal of Organic Chemistry
Magnus Mortén, Martin Hennum, Tore Bonge-Hansen
Rates for the thermal decomposition of ethyl halodiazoacetates (halo = Cl, Br, I) have been obtained, and reported herein are their half-lives. The experimental results are supported by DFT calculations, and we provide a possible explanation for the reduced thermal stability of ethyl halodiazoacetates compared to ethyl diazoacetate and for the relative decomposition rates between the chloro, bromo and iodo analogs. We have also briefly studied the thermal, non-catalytic cyclopropanation of styrenes and compared the results to the analogous Rh(II)-catalyzed reactions...
2016: Beilstein Journal of Organic Chemistry
Antonio Rosales, Ignacio Rodríguez-García
Cp2TiCl/D2O/Mn is an efficient combination, sustainable and cheap reagent that mediates the D-atom transfer from D2O to different functional groups and can contribute to the synthesis of new deuterated organic compounds under friendly experimental conditions and with great economic advantages.
2016: Beilstein Journal of Organic Chemistry
Roman Yu Peshkov, Elena V Panteleeva, Wang Chunyan, Evgeny V Tretyakov, Vitalij D Shteingarts
A convenient one-pot approach to alkylcyanobiaryls is described. The method is based on biaryl cross-coupling between the sodium salt of the terephthalonitrile dianion and a neutral aromatic nitrile in liquid ammonia, and successive alkylation of the long-lived anionic intermediate with alkyl bromides. The reaction is compatible with benzonitriles that contain methyl, methoxy and phenyl groups, fluorine atoms, and a 1-cyanonaphthalene residue. The variety of ω-substituted alkyl bromides, including an extra bromine atom, a double bond, cyano and ester groups, as well as a 1,3-dioxane fragment are suitable as alkylation reagents...
2016: Beilstein Journal of Organic Chemistry
Patrick Steinhoff, Michael E Tauchert
The reaction of CpPd(η (3) -C3H5) with the new diphosphinoborane ligand derivative (o-PCy2-C6H4)2BPh (Cy) DPB (Ph) affords the T-shape complex ( (Cy) DPB (Ph) )Pd(0) 9, which was characterized by X-ray analysis.
2016: Beilstein Journal of Organic Chemistry
Anne L Schöffler, Ata Makarem, Frank Rominger, Bernd F Straub
A dinuclear N-heterocyclic carbene (NHC) copper complex efficiently catalyzes azide-alkyne cycloaddition (CuAAC) "click" reactions. The ancillary ligand comprises two 4,5-dimethyl-1,3-thiazol-2-ylidene units and an ethylene linker. The three-step preparation of the complex from commercially available starting compounds is more straightforward and cost-efficient than that of the previously described 1,2,4-triazol-5-ylidene derivatives. Kinetic experiments revealed its high catalytic CuAAC activity in organic solvents at room temperature...
2016: Beilstein Journal of Organic Chemistry
Dirk Meyer, Thomas Strassner
A series of methylpalladium(II) complexes with pyrimidine-NHC ligands carrying different aryl- and alkyl substituents R ([((pym)^(NHC-R))Pd(II)(CH3)X] with X = Cl, CF3COO, CH3) has been prepared by transmetalation reactions from the corresponding silver complexes and chloro(methyl)(cyclooctadiene)palladium(II). The dimethyl(1-(2-pyrimidyl)-3-(2,6-diisopropylphenyl)imidazolin-2-ylidene)palladium(II) complex was synthesized via the free carbene route. All complexes were fully characterized by standard methods and in three cases also by a solid state structure...
2016: Beilstein Journal of Organic Chemistry
Hee Seung Jang, Yubin Kim, Dae Young Kim
Chiral binaphthyl-modified squaramide-catalyzed enantioselective addition of diphenyl phosphonate to ketimines derived from isatins has been achieved. This method affords practical and efficient access to chiral 3-amino-3-phosphonyl-substituted oxindole derivatives in high yields with excellent enantioselectivities (up to 99% ee).
2016: Beilstein Journal of Organic Chemistry
Franziska Hemmerling, Frank Hahn
This review highlights the biosynthesis of heterocycles in polyketide natural products with a focus on oxygen and nitrogen-containing heterocycles with ring sizes between 3 and 6 atoms. Heterocycles are abundant structural elements of natural products from all classes and they often contribute significantly to their biological activity. Progress in recent years has led to a much better understanding of their biosynthesis. In this context, plenty of novel enzymology has been discovered, suggesting that these pathways are an attractive target for future studies...
2016: Beilstein Journal of Organic Chemistry
Carl J Mallia, Gary C Walter, Ian R Baxendale
The flow synthesis of ortho-substituted carboxylic acids, using carbon monoxide gas, has been studied for a number of substrates. The optimised conditions make use of a simple catalyst system compromising of triphenylphosphine as the ligand and palladium acetate as the pre-catalyst. Carbon monoxide was introduced via a reverse "tube-in-tube" flow reactor at elevated pressures to give yields of carboxylated products that are much higher than those obtained under normal batch conditions.
2016: Beilstein Journal of Organic Chemistry
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