Regioselective carbon–carbon bond formation of 5,5,5-trifluoro-1-phenylpent-3-en-1-yne

• Motoki Naka,
• Tomoko Kawasaki-Takasuka and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2013, 9, 2182–2188, doi:10.3762/bjoc.9.256

• electrophiles, under equilibration of the possible two anionic species. Keywords: additives; computation; Li···F chelation; deprotonation; electron-withdrawing effect; organo-fluorine; Introduction We have previously reported [1] the interesting behavior of (E)-1-chloro-3,3,3-trifluoropropene ((E)-1) [2][3][4

•  2, aldehydes preferentially yielded 5 with qualitatively better ratio of 5/6 than the one of 4-d1/4-d2. Our computation of 4-Li1 and 4-Li2 by Gaussian 09W [20] using the B3LYP/6-31+G* level of theory uncovered that the former was energetically more favorable than the latter by 5.34 (3.67) kcal/mol

Topochemical control of the photodimerization of aromatic compounds by γ-cyclodextrin thioethers in aqueous solution

• Hai Ming Wang and
• Gerhard Wenz

Beilstein J. Org. Chem. 2013, 9, 1858–1866, doi:10.3762/bjoc.9.217

• mechanical calculations of the structures and interaction energies ΔE of the four COU dimers were performed using the Gaussian 03 software package to investigate the favored packing [47]. The aromatic dimers were fully optimized at the MP2/6-31G* level without any symmetry restriction during the computation

New tridecapeptides of the theonellapeptolide family from the Indonesian sponge Theonella swinhoei

• Annamaria Sinisi,
• Barbara Calcinai,
• Carlo Cerrano,
• Henny A. Dien,
• Angela Zampella,
• Claudio D’Amore,
• Barbara Renga,
• Stefano Fiorucci and
• Orazio Taglialatela-Scafati

Beilstein J. Org. Chem. 2013, 9, 1643–1651, doi:10.3762/bjoc.9.188

• able to significantly reduce the proliferation at 1 μM. At this dose, the proliferation reduction was equal to 20% (Figure 4, panel A; * p < 0.05 compared to untreated cells; n = 4). Computation of 50% inhibitory drug concentration (IC50) revealed that compounds 1, 2 and 3 were characterized by very

• mean ± standard error. Right panel: Computation of IC50 values. From top to bottom: Theonellapeptolide Id, sulfinyltheonellapeptolide and theonellapeptolide If (* p < 0.05 compared to untreated cells; n = 4). 1H (500 MHz) and 13C (125 MHz) NMR data of sulfinyltheonellapeptolide in CD3OD (2). 1H (500

Computational study of the rate constants and free energies of intramolecular radical addition to substituted anilines

• Andreas Gansäuer,
• Meriam Seddiqzai,
• Tobias Dahmen,
• Rebecca Sure and
• Stefan Grimme

Beilstein J. Org. Chem. 2013, 9, 1620–1629, doi:10.3762/bjoc.9.185

• systems. Kohn–Sham density functional theory (KS-DFT) has been proven to yield good accurate thermochemical properties within acceptable computation times [23][24][25]. However, the number of the proposed approximate exchange–correlation functionals to choose from is huge and they can suffer from severe

Host–guest complexes of mixed glycol-bipyridine cryptands: prediction of ion selectivity by quantum chemical calculations, part V

• Svetlana Begel,
• Ralph Puchta and
• Rudi van Eldik

Beilstein J. Org. Chem. 2013, 9, 1252–1268, doi:10.3762/bjoc.9.142

• structures were characterized as minima, transition structures, etc., by computation of vibrational frequencies. The relative energies were corrected for zero-point vibrational energies (ZPE). We deliberately did not include any solvent model for the sake of comparability with earlier studies [1][2][3][4

Tandem dinucleophilic cyclization of cyclohexane-1,3-diones with pyridinium salts

• Mostafa Kiamehr,
• Firouz Matloubi Moghaddam,
• Satenik Mkrtchyan,
• Volodymyr Semeniuchenko,
• Linda Supe,
• Alexander Villinger,
• Peter Langer and
• Viktor O. Iaroshenko

Beilstein J. Org. Chem. 2013, 9, 1119–1126, doi:10.3762/bjoc.9.124

• + regioselective reaction is inherent. Intrigued by this discrepancy, we computed the full reaction mechanism for cation 2a+ with potassium 3-oxocyclohex-1-enolate in the presence of potassium cation and hydrogencarbonate anion as base. We included HCO3− in our computation, both because it has only five atoms and

• the last reaction is a protonation of enamine in essence; the imaginary frequency inherent for TS 22a shows only proton displacement, without formation of a C–O bond. The latter was formed during IRC computation, starting from TS 22a. Previously, Hui Li and Chao-Guo Yan [50] proposed the nucleophilic

• scaling factor (0.9608) was applied. For every located transition state an IRC calculation at the same level of theory confirmed that this TS connects the corresponding educts/intermediates/products. The methodology of local softness computation [59][60] uses Fukui functions; for their approximation we

Interplay of ortho- with spiro-cyclisation during iminyl radical closures onto arenes and heteroarenes

• Roy T. McBurney and
• John C. Walton

Beilstein J. Org. Chem. 2013, 9, 1083–1092, doi:10.3762/bjoc.9.120

• computation [38] that gave hfs in close agreement with experiment (Table 1). This was a surprising result because previously the only radicals of type 9 that had been spectroscopically detected had resulted from additions of phenyl [34] or bridgehead radicals (bicyclo[2.2.2]oct-1-yl and adamantyl) [39]. These

• resolved spectra only at 230–235 K (Figure 3). The corresponding benzofuranyl-iminyl was not detectable at 230 K or above. The EPR hfs obtained from simulation of the spectrum (Table 2) show this to be a benzyl type radical and we assign it structure 12a (Scheme 2). A DFT computation for 12a at the UB3LYP

Ring opening of 2-aza-3-borabicyclo[2.2.0]hex-5-ene, the Dewar form of 1,2-dihydro-1,2-azaborine: stepwise versus concerted mechanisms

• Holger F. Bettinger and
• Otto Hauler

Beilstein J. Org. Chem. 2013, 9, 761–766, doi:10.3762/bjoc.9.86

• have performed explorative computations using the CASSCF(6,6)/6-31G* method and could locate transition states for the conrotatory (TS1; nimag = 1, i556 cm−1) and disrotatory (TS2; nimag = 1, i628 cm−1) ring opening of 3. Computation of the intrinsic reaction coordinates confirms that both TS1 and TS2

• -dihydro-1,2-azaborine system, while the four π and π* orbitals along with the C3–C6 σ/σ* orbitals were used for the Dewar form 3 and transition states TS1 and TS2. Geometries were fully optimised and the nature of stationary points was confirmed by analytic computation of second derivatives. Intrinsic

Electron and hydrogen self-exchange of free radicals of sterically hindered tertiary aliphatic amines investigated by photo-CIDNP

• Martin Goez,
• Isabell Frisch and
• Ingo Sartorius

Beilstein J. Org. Chem. 2013, 9, 437–446, doi:10.3762/bjoc.9.46

• this uncertainty, an elaborate computation of λi is not justified, but the calculated activation parameter is seen to be in very good agreement with the experimental result of Table 2. Finally, the slightly smaller molecular size of DABCO (d1 = d2 = 6.2 Å; d = 5.7 Å) leads to a computed increase of

Alkene selenenylation: A comprehensive analysis of relative reactivities, stereochemistry and asymmetric induction, and their comparisons with sulfenylation

• Vadim A. Soloshonok and
• Donna J. Nelson

Beilstein J. Org. Chem. 2011, 7, 744–758, doi:10.3762/bjoc.7.85

• alkene IEs and required reasonable computation time. Although this computational method may not give absolute HOMO energy values, it was successfully used in similar, previous studies [72][73][74][75][76][77][78], and it was proven to be sufficiently accurate in correlations with IEs and the relative

EPR and pulsed ENDOR study of intermediates from reactions of aromatic azides with group 13 metal trichlorides

• Giorgio Bencivenni,
• Riccardo Cesari,
• Daniele Nanni,
• Hassane El Mkami and
• John C. Walton

Beilstein J. Org. Chem. 2010, 6, 713–725, doi:10.3762/bjoc.6.84

• +•, containing a single F-atom. The DFT computation on the dimer hfs gave satisfactory agreement (Table 1), with the possible exception of the para-F hfs. However, DFT-computed a(F) values varied from 7.2, to 7.1, to 9.5 and 4.3 G with 6-31G(d), 6-31+G(d,p), DGDZVP and 6-311++G(d,p) basis sets, respectively

Prediction of reduction potentials from calculated electron affinities for metal-salen compounds

• Sarah B. Bateni,
• Kellie R. England,
• Anthony T. Galatti,
• Handeep Kaur,
• Victor A. Mendiola,
• Alexander R. Mitchell,
• Michael H. Vu,
• Benjamin F. Gherman and
• James A. Miranda

Beilstein J. Org. Chem. 2009, 5, No. 82, doi:10.3762/bjoc.5.82

• predict reduction potentials, we hoped to establish a method of assessing the suitability of prospective metal-salen catalysts other than Ni(II)-salen as electrocatalysts in the ERC reaction. The indirect computation of reduction potentials in this manner avoids the need to compute solvation enthalpies

• (Epc) of the 19 metal-salens were then measured experimentally using cyclic voltammetry. Analogous methods were applied to obtain the Epc for a test set of 14 metal-salens employing a variety of new metals and substituents. Concurrently, density functional theory calculations enabled computation of EAs

Synthesis of chiral cyclohexanes and carbasugars by 6-exo-dig radical cyclisation reactions

• Rajeev K. Shrivastava,
• Elise Maudru,
• Gurdial Singh,
• Richard H. Wightman and
• Keith M. Morgan

Beilstein J. Org. Chem. 2008, 4, No. 43, doi:10.3762/bjoc.4.43

• order to simplify the computation, (18 and 19). At low energies of 34.539 and 34.909 kcal/mol (Figure 2), the “trans” isomer 18 favours a boat conformation, in which the carbon-carbon double bond is above the plane of the ring and the methoxy group is in axial position and as a consequence the vinyl

Inversion symmetry and local vs. dispersive interactions in the nucleation of hydrogen bonded cyclic n-mer and tape of imidazolecarboxamidines

• Sihui Long,
• Venkatraj Muthusamy,
• Peter G. Willis,
• Sean Parkin and
• Arthur Cammers

Beilstein J. Org. Chem. 2008, 4, No. 23, doi:10.3762/bjoc.4.23

• (disordered or too small) were obtained. Hydrogen bonded dimers possessing inversion centers, Ci dimers, comprised the most popular bonding motif found in the solid state imidazolecarboxamidines. To investigate the nature of this energetic preference we compared by computation the gas-phase stabilities of