Isoxazolium N-ylides and 1-oxa-5-azahexa-1,3,5-trienes on the way from isoxazoles to 2H-1,3-oxazines

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Yelizaveta G. Gorbunova,
• Ekaterina E. Galenko,
• Kirill I. Mikhailov,
• Viktoriia V. Pakalnis and
• Margarita S. Avdontceva

Beilstein J. Org. Chem. 2014, 10, 1896–1905, doi:10.3762/bjoc.10.197

• and kinetic stabilities of isoxazolium N-ylides, probable intermediates in a carbenoid- or carbene-mediated one-atom isoxazole ring expansion. Preliminary calculations at the DFT B3LYP/6-31G(d) level with the PCM solvation model for dichloromethane were performed for the model reaction of isoxazoles A

• of compound 3a in the crystal corresponds to the most stable conformer according to calculations at DFT B3LYP/6-31G(d) level in vacuo (ΔΔG298 K (equatorial/axial = 1.2 kcal/mol). One of the possible reasons for the higher stability of conformer 3a with a pseudo-axial methoxycarbonyl group in

• isolated) – the corresponding changes in Gibbs free energy were evaluated from isodesmic reactions 1–4 (Scheme 4). These calculations were based on the Gibbs free energy of the compounds, which were obtained by DFT B3LYP/6-31G(d) calculations (ΔΔG298 K, kcal/mol). Although the substitution of the Ph group

Domino reactions of 2H-azirines with acylketenes from furan-2,3-diones: Competition between the formation of ortho-fused and bridged heterocyclic systems

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Viktoriia V. Pakalnis,
• Roman O. Iakovenko and
• Dmitry S. Yufit

Beilstein J. Org. Chem. 2014, 10, 784–793, doi:10.3762/bjoc.10.74

• compounds, with a new heterocyclic skeleton, are the result of the coupling of two molecules of azirine and two molecules of acylketene and can be prepared only from 3-aryl-2H-azirines having no electron-withdrawing groups in the aryl substituent. Calculations at the DFT B3LYP/6-31G(d) level for the various

• :1 or 1:1 adducts: 5,7-dioxa-1-azabicyclo[4.4.1]undeca-3,8-diene or 5-oxa-1-azabicyclo[4.1.0]hept-3-ene derivatives. From the results of DFT B3LYP/6-31G(d) computations a step-wise mechanism appears likely for the formation of [4 + 2]-monoadducts [22]. The main limitation for the synthetic

• than that of trans-isomer 5. The formation of compounds 3 proceeds in the same way as for similar compounds obtained by reaction of azirines with acylketenes from diazo compounds (Scheme 2) [22]. According to the calculation at the DFT B3LYP/6-31G(d) level with PCM solvation model for benzene (Figure 2

Elucidation of the regio- and chemoselectivity of enzymatic allylic oxidations with Pleurotus sapidus – conversion of selected spirocyclic terpenoids and computational analysis

• Verena Weidmann,
• Mathias Schaffrath,
• Holger Zorn,
• Julia Rehbein and
• Wolfgang Maison

Beilstein J. Org. Chem. 2013, 9, 2233–2241, doi:10.3762/bjoc.9.262

• Supporting Information File 1) of relative radical stabilities and bond-dissociation enthalpies (BDH298) based on DFT (B3LYP/6-31+G** and B3LYP/6-31G* + PCM) and composite method (CBS-QB3) calculations enable a quantification and visual rationalization of the observed experimental results. Since PCM and gas

Structure of 1,5-benzodiazepinones in the solid state and in solution: Effect of the fluorination in the six-membered ring

• Marta Pérez-Torralba,
• Rosa M. Claramunt,
• M. Ángeles García,
• Concepción López,
• M. Carmen Torralba,
• M. Rosario Torres,
• Ibon Alkorta and
• José Elguero

Beilstein J. Org. Chem. 2013, 9, 2156–2167, doi:10.3762/bjoc.9.253

• -033; email: deposit@ccdc.cam.ac.uk). Theoretical calculations. The geometry of the molecules has been fully optimized with the hybrid HF/DFT B3LYP [29][30][31] computational method and the 6-31G(d) basis set [32]. Frequency calculations have been carried out at the same computational level to verify

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

• Erlangen, Germany 10.3762/bjoc.9.142 Abstract The selectivity of the cryptands [2.2.bpy] and [2.bpy.bpy] for the endohedral complexation of alkali, alkaline-earth and earth metal ions was predicted on the basis of the DFT (B3LYP/LANL2DZp) calculated structures and complex-formation energies. The cavity

• selective complexation was not investigated experimentally. As mentioned above, the complexation of alkali and alkaline-earth metal ions by different cryptands was investigated extensively in our group on the basis of DFT (B3LYP/LANL2DZp) calculations [1][2][3][4]. Within the framework of this study

Asymmetric Diels–Alder reaction with >C=P– functionality of the 2-phosphaindolizine-η¹-P-aluminium(O-menthoxy) dichloride complex: experimental and theoretical results

• Rajendra K. Jangid,
• Nidhi Sogani,
• Neelima Gupta,
• Raj K. Bansal,
• Moritz von Hopffgarten and
• Gernot Frenking

Beilstein J. Org. Chem. 2013, 9, 392–400, doi:10.3762/bjoc.9.40

• diastereoselectivity to afford [2 + 4] cycloadducts. Calculation of the model substrate, 3-methoxycarbonyl-1-methyl-2-phosphaindolizine-P-aluminium(O-menthoxy) dichloride (7a), at the DFT (B3LYP/6-31+G*) level reveals that the O-menthoxy moiety blocks the Re face of the >C=P– functionality, due to which the activation

• DA reactions of 2-phosphaindolizine-η1-P-AlEtCl2 complexes [21]. Theoretical calculations at the DFT (B3LYP/6-31+G**) level indicated lowering of the activation barrier by 6 kcal mol–1 for the reaction of σ2,λ3-P-coordinated 2-phosphindolizine to methylaluminium dichloride with 1,3-butadiene as

• theoretically the mode of action of the chiral auxiliary in directing the complete diastereoselectivity of the DA reactions. The following model DA reactions (Scheme 5) were calculated at the DFT (B3LYP/6-31+G*) level. Computational calculations It has been reported that for determining activation free energies

Amino-substituted diazocines as pincer-type photochromic switches

• Hanno Sell,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2013, 9, 1–7, doi:10.3762/bjoc.9.1

• (isobutane): m/z (% relative intensity) 323 (100) [M + H]+. Configurations and conformations of 5,6-dihydrodibenzo[c,g][1,2]diazocine (1), and DFT (B3LYP/6-31G*) calculated energies (kcal mol−1) relative to the most stable cis boat form. Dipol moments are given in Debye. Crystal structures of the cis isomers

• gaussian09 input file of the geometry optimization of the complex of cis-5 and ethylenediamine (DFT B3LYP/6-31+G**). Supporting Information File 357: Additional NMR spectra and 1H NMR binding study of 3,3-acetamido-EBAB (5) with ethylenediamine. Supporting Information File 358: Crystallographic information

Toward unidirectional switches: 2-(2-Hydroxyphenyl)pyridine and 2-(2-methoxyphenyl)pyridine derivatives as pH-triggered pivots

• Christina Tepper and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2012, 8, 977–985, doi:10.3762/bjoc.8.110

• unidirectionally. Another result is found for the switch 10: If we compare the simulated spectra of (M)-10 and (P)-10, using time-dependent density functional theory (TD-DFT-B3LYP/6-31G*; Figure 7b) with the measured spectrum of 10 in DCM (Figure 7a), it becomes evident that the M isomer is the prevailing one. The

• M) at 20 °C upon addition of 10 (yellow) and 30 equiv TFA (12, red). (b) Calculated spectra of (M)-13 (blue) and (P)-13 (brown) by using TD-DFT-B3LYP/6-31G*. (a) CD spectral change of pyridine switch 10 (blue) in dichloromethane (c = 5.6 × 10–5 M) at 20 °C upon addition of 1 (yellow) and 20 equiv

• TFA (11, red). (b) Calculated spectra of (M)-10 (blue) and (P)-10 (brown) by using TD-DFT-B3LYP/6-31G*. Principle of the switching mechanism of 2-(2-hydroxyphenyl)pyridine (2) and 2-(2-methoxyphenyl)pyridine (3). Principle of the switching mechanism of 2-(2-hydroxyphenyl)-3-methylpyridine (6) and 2-(2

Synthesis and anion recognition properties of shape-persistent binaphthyl-containing chiral macrocyclic amides

• Marco Caricato,
• Nerea Jordana Leza,
• Claudia Gargiulli,
• Giuseppe Gattuso,
• Daniele Dondi and
• Dario Pasini

Beilstein J. Org. Chem. 2012, 8, 967–976, doi:10.3762/bjoc.8.109

• . Preliminary conformational structures were optimized by using the semiempirical PM3 method [38]. The geometries were then subjected to further refinement by using DFT B3LYP/6-31G(d) methods. In order to locate conformers having the minimum energy, the structures obtained by preliminary optimization were then

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

• % and 65% yield, respectively. Computational methods The ground-state (S0) geometries were optimized by means of density functional theory (DFT) with the B3LYP hybrid functional and 6-311G(d,p) [11] basis set (DFT(B3LYP)/6-311G(d,p)). The first excited-state (S1) geometries were optimized with

• ; H, 4.32; N, 16.11. (a) HOMO and (b) LUMO for 3a, computed with TD-DFT(B3LYP)/6-31+G(d,p). The pink (blue) lobes indicate a positive (negative) isocontour value of 0.03. The distribution of the HOMO minus LUMO density for 3a, computed with TD-DFT(B3LYP)/6-31+G(d,p). The pink (blue) lobes indicate a

Photoinduced homolytic C–H activation in N-(4-homoadamantyl)phthalimide

• Nikola Cindro,
• Margareta Horvat,
• Kata Mlinarić-Majerski,
• Axel G. Griesbeck and
• Nikola Basarić

Beilstein J. Org. Chem. 2011, 7, 270–277, doi:10.3762/bjoc.7.36

• availability of H-atoms in the homoadamantane skeleton for the abstraction by the phthalimide, molecular modeling was performed. The geometry of 5 was optimized by DFT B3LYP/6-31G method (Figure 1) [61]. Investigation of the distances between the carbonyl groups of the phthalimide moiety and the H-atoms of the

• optimization was performed by use of DFT B3LYP/6-31G. Photoinduced domino reaction of adamantylphthalimide. Synthesis of homoadamantylphthalimide 5. Products after irradiation of 5. Proposed mechanism for the photochemical transformation of 5. Supporting Information Supporting Information File 48: Supporting

Intramolecular hydroxycarbene C–H-insertion: The curious case of (o-methoxyphenyl)hydroxycarbene

• Dennis Gerbig,
• David Ley,
• Hans Peter Reisenauer and
• Peter R. Schreiner

Beilstein J. Org. Chem. 2010, 6, 1061–1069, doi:10.3762/bjoc.6.121

• that this compound was not present among the pyrolysis products. Even after more than 12 h in the dark at 11 K, the IR spectrum was unchanged, indicating that there is no compound among the pyrolysis products that is susceptible to a tunneling decay mechanism. The TD-DFT (B3LYP/cc-pVDZ) absorption

Control of asymmetric biaryl conformations with terpenol moieties: Syntheses, structures and energetics of new enantiopure C₂-symmetric diols

• Y. Alpagut,
• B. Goldfuss and
• J.-M. Neudörfl

Beilstein J. Org. Chem. 2008, 4, No. 25, doi:10.3762/bjoc.4.25

• )); parameters refined: 441; R1 = 0.0410, wR2 = 0.1097; GOF = 1.180 (crystallographic data have been deposited with the Cambridge Crystallographic Data Centre). Computational Section All computed structures were fully optimized using Morokuma's ONIOM method implemented in GAUSSIAN98 [33]. Hybrid DFT (B3LYP/6-31