Synthesis, solid-state fluorescence properties, and computational analysis of novel 2-aminobenzo[4,5]thieno[3,2-d]pyrimidine 5,5-dioxides

• Kenichirou Yokota,
• Masayori Hagimori,
• Naoko Mizuyama,
• Yasuhisa Nishimura,
• Hiroshi Fujito,
• Yasuhiro Shigemitsu and
• Yoshinori Tominaga

Beilstein J. Org. Chem. 2012, 8, 266–274, doi:10.3762/bjoc.8.28

• of trustworthy quality. The CASSCF peak, in contrast, overshoots the experimental peak. The best prediction was obtained by using the most elaborate method, MS-CASPT2, which can take the majority of the electronic correlations into account. The MS-CASPT2 result indicates that the excitation character

The interplay of configuration and conformation in helical perylenequinones: Insights from chirality induction in liquid crystals and calculations

• Elisa Frezza,
• Silvia Pieraccini,
• Stefania Mazzini,
• Alberta Ferrarini and
• Gian Piero Spada

Beilstein J. Org. Chem. 2012, 8, 155–163, doi:10.3762/bjoc.8.16

• ) was investigated by integrating measurements of helical twisting power with a conformational analysis by DFT calculations and with the prediction of their twisting ability by the surface-chirality method. The two quasi-enantiomeric derivatives induce oppositely handed cholesteric phases when

• ) calculations, and with the prediction of the twisting ability of conformers, by the surface chirality (SC) method [29]. Results and Discussion HTP measurement The propensity of a dopant to induce a helical organization in the liquid-crystalline matrix is measured by its helical twisting power, which is defined

• data are available. However, the prediction that χ1 ~ χ2 ~ 30° appears reasonable for 2, considering that the narrower χ1 angle in cercosporin is a consequence of the constraints imposed by the bridge in the “6,7-bay region”. In view of their higher stability, only conformers in the propeller form were

Natural product biosyntheses in cyanobacteria: A treasure trove of unique enzymes

• Jan-Christoph Kehr,
• Douglas Gatte Picchi and
• Elke Dittmann

Beilstein J. Org. Chem. 2011, 7, 1622–1635, doi:10.3762/bjoc.7.191

• . Conclusion Genome sequencing projects of cyanobacteria have revealed a far greater potential of cyanobacteria to produce natural products than expected. It can thus be anticipated that genomic mining techniques that start with the theoretical prediction of structures from genomic data will be of increasing

Predicting the UV–vis spectra of oxazine dyes

• Scott Fleming,
• Andrew Mills and
• Tell Tuttle

Beilstein J. Org. Chem. 2011, 7, 432–441, doi:10.3762/bjoc.7.56

• predict the absorption spectra of a series of oxazine dyes and the effect of solvent on the accuracy of these predictions. Based on the results of this study, it is clear that for the series of oxazine dyes an accurate prediction of the excitation energy requires the inclusion of solvent. Implicit solvent

• the prediction of the λmax value of 1 (M06-L error: 69 nm; −0.30 eV). Surprisingly, the gas-phase calculated value of λmax for 1 is relatively accurate. The gas-phase B3LYP calculation of 1 underestimates the value of λmax by only 16 nm (0.08 eV), although this appears to be a fortuitous error

• have investigated the ability of TD-DFT to predict the absorption spectra of a series of oxazine dyes and the effect of solvent on the accuracy of these predictions. Based on the results of this study, it is clear that for the series of oxazine dyes and accurate prediction of the excitation energy

Accuracy in determining interproton distances using Nuclear Overhauser Effect data from a flexible molecule

• Catharine R. Jones,
• Craig P. Butts and
• Jeremy N. Harvey

Beilstein J. Org. Chem. 2011, 7, 145–150, doi:10.3762/bjoc.7.20

• Catharine R. Jones Craig P. Butts Jeremy N. Harvey Department of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, United Kingdom 10.3762/bjoc.7.20 Abstract The determination of accurate NOE-derived interproton distances and confirmation/prediction of relative populations in

Organic gelators and hydrogelators

• Jean-Pierre Desvergne

Beilstein J. Org. Chem. 2010, 6, 846–847, doi:10.3762/bjoc.6.99

• . However, despite numerous efforts to establish a structure-property relationship for the development of low molecular weight gelling agents, prediction of the gelling ability of a compound is not straightforward. A major challenge today is the rational design of small size molecular gelators coupled with

Kinetic studies and predictions on the hydrolysis and aminolysis of esters of 2-S-phosphorylacetates

• Milena Trmčić and
• David R. W. Hodgson

Beilstein J. Org. Chem. 2010, 6, 732–741, doi:10.3762/bjoc.6.87

• features a PDF document presenting details of studies using the bromoacetyl-OBt system 1 (R = Bt) and bromoacetyl-NHS system 1 (R = NHS), and associated experimental details, as well as Excel™ spreadsheets for the prediction of product outcomes and the optimisation of leaving group pKaH values of 2-S

• -thiophosphate esters with reference to controlling aminolysis over hydrolysis. Supporting Information File 129: Synthesis and application of bromoacetyl-OBt and NHS systems Supporting Information File 130: Prediction of product distribution using p-nitrophenyl ester 7 (R = pNP) Supporting Information File 131

• : Prediction of product distribution using m-nitrophenyl ester 7 (R = mNP) Supporting Information File 132: Optimisation of leaving group pKaH values of 2-S-thiophosphate esters Acknowledgements We thank the Department of Chemistry, Durham University for support in the form of a studentship (MT), and the

Recognition properties of receptors consisting of imidazole and indole recognition units towards carbohydrates

• Monika Mazik and
• André Hartmann

Beilstein J. Org. Chem. 2010, 6, No. 9, doi:10.3762/bjoc.6.9

• building blocks for the acyclic structures, effective carbohydrate receptors with different binding selectivities could be obtained. However, the exact prediction of the binding selectivity still represents an unsolved problem. Binding studies in homogeneous solution The interactions of the receptors and

• into the acyclic receptor structure, effective carbohydrate receptors with different binding preferences can be generated. However, the exact prediction of the binding preference still represents an unsolved problem and remains an important goal for future research. Experimental section Analytical TLC

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

• predicted from computed EAs using the linear correlation derived from the training set. In addition, Fry has also recently published an account of a similar procedure in the prediction of oxidation potentials of substituted triphenylamines using density functional theory [8]. In that work, Fry explored

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

• minimization and their level of accuracy, especially in the prediction of hydrogen bonding options that are proximal in energy [28][46][47]. Prediction of the organic solid state is challenged by the fact that many crystalline phases likely result from marginal differences in large opposing effects. While the

• be made about the most popular hydrogen bond motif followed by caveats regarding the use of crystal-structure derived atomic parameters to broadly characterize hydrogen bonding energies. 1: An intuitive prediction regarding the relationship between crude hydrogen bond donor/acceptor directionality

• obvious exceptions. See text. The icon legend is identical to Figure 8 and Figure 10. The Y-axis from Figure 8 energies (θ only) and the X-axis from Figure 10 energies are compared. The high and low energies of θ are mostly responsible for the two crystalline phases that lie outside the prediction that

Tether- directed synthesis of highly substituted oxasilacycles via an intramolecular allylation employing allylsilanes

• Peter J. Jervis and
• Liam R. Cox

Beilstein J. Org. Chem. 2007, 3, No. 6, doi:10.1186/1860-5397-3-6

• all four possible oxasilacycles in addition to appreciable quantities of a diene side-product. The results with anti-aldehydes are more interesting. In line with our prediction, substrates possessing this relative stereochemistry provide results which are comparable to those from aldehydes that lack a

Effect of transannular interaction on the redox- potentials in a series of bicyclic quinones

• Grigoriy Sereda,
• Jesse Van Heukelom,
• Miles Koppang,
• Sudha Ramreddy and
• Nicole Collins

Beilstein J. Org. Chem. 2006, 2, No. 26, doi:10.1186/1860-5397-2-26

• calculated parameters and to the nature and positions of substituents in the bicyclic system. Results and Discussion Accurate computational prediction of redox-potentials requires comparison of energies for both the starting quinone and its reduced forms. The open-shell nature of the reduced species and

• often the necessity to take into account solvation makes the prediction of the redox-potentials a challenging and time consuming computational problem. However, Koopmans' theorem [4] enabled us to relate redox-potentials of bicyclic quinones with their LUMO energies, which characterize solely the

• starting compound. Despite the neglected orbital relaxation that immediately follows the reduction, such correlations have proved to be an efficient tool for prediction of redox-potentials of anthracyclines [5], substituted anthracenes [6], and oligothiophenes [7]. For all chemical species, the

EcoScale, a semi- quantitative tool to select an organic preparation based on economical and ecological parameters

• Koen Van Aken,
• Lucjan Strekowski and
• Luc Patiny

Beilstein J. Org. Chem. 2006, 2, No. 3, doi:10.1186/1860-5397-2-3

• not take into account the nature and environmental impact of the generated waste. In order to arrive at a more meaningful prediction, the E-factor is multiplied by a environmentally hazardous quotient Q. For example, a Q value of 1 can be attributed to NaCl, while heavy metals can be assigned a value