Stereochemistry of ring-opening/cross metathesis reactions of exo- and endo-7-oxabicyclo[2.2.1]hept-5-ene-2-carbonitriles with allyl alcohol and allyl acetate

• Piotr Wałejko,
• Michał Dąbrowski,
• Lech Szczepaniak,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 1893–1901, doi:10.3762/bjoc.11.204

• , however, some electronic effects in 7-oxanorbornene should be also taken into consideration. Unexpectedly, the Z-selectivity predominated in most reactions catalyzed by [Ru]1 (see Table 1, entries 1–6, 10–15, and Table 2, entries 1–4). A two-fold excess of the Z isomer was observed in both groups of

• strained than D. On the other hand, an interaction of less bulky o-tolyl ligands with the ruthenium core in [Ru]5 causes an opposite selectivity (E preference). One can assume that the observed change in the E/Z selectivity resulted from chelating and electronic effects in postulated intermediates C and D

A comprehensive study of olefin metathesis catalyzed by Ru-based catalysts

• Albert Poater and
• Luigi Cavallo

Beilstein J. Org. Chem. 2015, 11, 1767–1780, doi:10.3762/bjoc.11.192

• , respectively. Steric effects have little influence on the absolute C2H4 binding energy, E of 3rd column in Table 2, since rather similar values are calculated for 2 and 5 (−18.6 and −19.1 kcal/mol, respectively). Differently, electronic effects influence the ability of the Ru atom to capture C2H4, particularly

• differentiation between the power of the three effects, steric, electronic and solvent, has turned out be a hazard to make predictions difficult. However the CF3 groups have become key to explain the electronic effects, as well as the t-Bu for steric effects. Steric effects owing to interaction between bulky NHC

First principle investigation of the linker length effects on the thermodynamics of divalent pseudorotaxanes

• Andreas J. Achazi,
• Doreen Mollenhauer and
• Beate Paulus

Beilstein J. Org. Chem. 2015, 11, 687–692, doi:10.3762/bjoc.11.78

• linker shows an enhanced binding strength due to electronic effects, namely the dispersion interaction between the linkers from the guest and the host. For the longer linkers this ideal packing is not possible due to steric hindrance. Keywords: density functional theory (DFT); dispersion correction

• first principle calculations show clearly that this enhanced binding is due to electronic effects, namely the dispersion interaction of the two linkers. For the shortest linker this interaction results in a nearly ideal π–π stacking. For the two longer linkers ideal packing is not possible due to steric

Hydrogenation of unactivated enamines to tertiary amines: rhodium complexes of fluorinated phosphines give marked improvements in catalytic activity

• Sergey Tin,
• Tamara Fanjul and
• Matthew L. Clarke

Beilstein J. Org. Chem. 2015, 11, 622–627, doi:10.3762/bjoc.11.70

• as purification step, particularly if catalysts could be recycled, although that is likely to be challenging in moisture sensitive catalytic hydrogenation chemistry. The ligand electronic effects seem counter intuitive at first glance, but they support the finding by DFT calculations that enamine

Metal-free one-pot synthesis of 2-substituted and 2,3-disubstituted morpholines from aziridines

• Hongnan Sun,
• Binbin Huang,
• Run Lin,
• Chao Yang and
• Wujiong Xia

Beilstein J. Org. Chem. 2015, 11, 524–529, doi:10.3762/bjoc.11.59

• -disubstituted aziridines (acyclic and/or cyclic ones), separable mixtures of regioisomers 3l,m and 4l,m were obtained arising from isomeric ring opening (Table 2, entries 12 and 13). We speculated that the observed regioselectivity might depend on the combined action of electronic effects and the position of

An unusually stable chlorophosphite: What makes BIFOP–Cl so robust against hydrolysis?

• Roberto Blanco Trillo,
• Jörg M. Neudörfl and
• Bernd Goldfuss

Beilstein J. Org. Chem. 2015, 11, 313–322, doi:10.3762/bjoc.11.36

• ). This result demonstrates that steric and electronic effects can be used to render the inherently highly reactive and electrophilic phosphorus–halogen units essentially inert against nucleophilic reagents. The stability of BIFOP–Cl (and other phosphorus–halogen systems) against nucleophiles promotes its

Azirinium ylides from α-diazoketones and 2H-azirines on the route to 2H-1,4-oxazines: three-membered ring opening vs 1,5-cyclization

• Nikolai V. Rostovskii,
• Mikhail S. Novikov,
• Alexander F. Khlebnikov,
• Galina L. Starova and
• Margarita S. Avdontseva

Beilstein J. Org. Chem. 2015, 11, 302–312, doi:10.3762/bjoc.11.35

• depends on the electronic effects of the para substituents in the aryl group of 3-aryl-2H-azirine 1. The [3.2.1] adduct is preferably formed from azirines 1e,f with electron-donating substituents (Table 1, entries 7 and 8), while 3-(4-nitrophenyl)-2H-azirine (1g) provides the [4.3.1] adduct only (Table 1

Synthesis and biological evaluation of novel N-α-haloacylated homoserine lactones as quorum sensing modulators

• Michail Syrpas,
• Ewout Ruysbergh,
• Christian V. Stevens,
• Norbert De Kimpe and
• Sven Mangelinckx

Beilstein J. Org. Chem. 2014, 10, 2539–2549, doi:10.3762/bjoc.10.265

• affinity of AHL analogues with the cognate receptor [18]. However, the activity of the novel compounds is modulated by the steric and electronic effects induced by the larger halo substituents. Furthermore, the absence of antagonistic activity of the novel analogues and the retained QS activity of most of

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• the preparation of a wide array of cyclopentenes with two adjacent chiral centers, with good enantiomeric excesses and satisfactory to good regioselectivities. These transformations were slightly influenced by electronic effects. Notably, Fu et al. successfully applied this approach to construct

• to furnish a wide range of spirocyclopenteneoxindoles in moderate to excellent yields and ee's (Scheme 38). The yields and stereoselectivities were significantly influenced not by electronic effects but by aromatic interactions. Aryl-substituted MBH carbonates reacted smoothly to afford

An experimental and theoretical NMR study of NH-benzimidazoles in solution and in the solid state: proton transfer and tautomerism

• Carla I. Nieto,
• Pilar Cabildo,
• M. Ángeles García,
• Rosa M. Claramunt,
• Ibon Alkorta and
• José Elguero

Beilstein J. Org. Chem. 2014, 10, 1620–1629, doi:10.3762/bjoc.10.168

• the substituent at position 2 on the rate (roughly, CF3 and H, fast; CH2C6H5 and CH3, slow) is probably the consequence of steric and electronic effects; many years ago, we showed that intramolecular hydrogen bonds also affect the rate [34]. The calculated electrostatic potential minima associated to

The Ugi four-component reaction as a concise modular synthetic tool for photo-induced electron transfer donor-anthraquinone dyads

• Sarah Bay,
• Gamall Makhloufi,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 1006–1016, doi:10.3762/bjoc.10.100

• reference systems 2, 3, and 10 clearly shows that the donor and anthraquinone moieties are essentially electronically decoupled in the electronic ground state. Therefore, in the electronic ground state the electronic effects should behave additively, i.e., as if the donors and anthraquinones were placed at

Aza-Diels–Alder reaction between N-aryl-1-oxo-1H-isoindolium ions and tert-enamides: Steric effects on reaction outcome

• Amitabh Jha,
• Ting-Yi Chou,
• Zainab ALJaroudi,
• Bobby D. Ellis and
• T. Stanley Cameron

Beilstein J. Org. Chem. 2014, 10, 848–857, doi:10.3762/bjoc.10.81

• been studied. In continuation of our efforts on the development of novel synthetic methodologies [27][28][29][30][31][32][33][34][35][36], we report herein a systematic study of steric and electronic effects of aryl substituents leading to substituted 6,6a-dihydroisoindolo[2,1-a]quinolin-11(5H)-ones

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

• results in the highest yields of the products (Table 1). Reactions of azirines 2a–c and furandiones 1a–c, containing electron-donating and electron-withdrawing groups in the aryl rings, were studied to determine an influence of substituents with different electronic effects on the product distribution

• . Analysis of the data obtained (Table 2) shows that the ratio of the products 3–5 is determined by the electronic effects of the substituents in the benzene rings both in arylazirine 2 and arylfurandione 1. An increase of the electron-withdrawing effect of substituents in the benzene rings of 3-aryl-2H

• azirine with two molecules of acylketene. The ratio of the adducts 3–5 is determined by electronic effects of the substituents in the benzene rings both in arylazirine 2 and arylfurandione 1. The increase of the electron-withdrawing effect of the substituents in the benzene rings of the arylazirine leads

Synthesis, characterization and initial evaluation of 5-nitro-1-(trifluoromethyl)-3H-1λ³,2-benziodaoxol-3-one

• Nico Santschi,
• Roman C. Sarott,
• Elisabeth Otth,
• Reinhard Kissner and
• Antonio Togni

Beilstein J. Org. Chem. 2014, 10, 1–6, doi:10.3762/bjoc.10.1

• ppm). Furthermore, this comparison highlights that the replacement of the chlorine atom by the CF3 group to a certain degree compensates the electronic effects imposed by the NO2 group as indicated by the lessened extent of deshielding. Nitration also had a distinct effect on the electronic spectrum

Diastereoselectivity in the Staudinger reaction of pentafluorosulfanylaldimines and ketimines

• Alexander Penger,
• Cortney N. von Hahmann,
• Alexander S. Filatov and
• John T. Welch

Beilstein J. Org. Chem. 2013, 9, 2675–2680, doi:10.3762/bjoc.9.303

• Debye respectively [7][8]. When these electronic effects are combined with an occupied volume only slightly less than that of a tert-butyl group [3][13], the SF5 group can have unanticipated influences on the structure such as anchoring side chain and neighboring hydroxy group conformations [14][15

Sequential Diels–Alder/[3,3]-sigmatropic rearrangement reactions of β-nitrostyrene with 3-methyl-1,3-pentadiene

• Peter A. Wade,
• Alma Pipic,
• Matthias Zeller and
• Panagiota Tsetsakos

Beilstein J. Org. Chem. 2013, 9, 2137–2146, doi:10.3762/bjoc.9.251

• depend on electronic effects. The polar transition state 29 has been proposed and appears to be consistent with the currently available rate data. Experimental General methods 3-Methyl-1,3-pentadiene (E/Z mixtures), (E)-3-methyl-1,3-pentadiene (E/Z, 99.7:0.3), tin(IV) chloride, and β-nitrostyrene were

Mechanistic studies on the CAN-mediated intramolecular cyclization of δ-aryl-β-dicarbonyl compounds

• Brian M. Casey,
• Dhandapani V. Sadasivam and
• Robert A. Flowers II

Beilstein J. Org. Chem. 2013, 9, 1472–1479, doi:10.3762/bjoc.9.167

• products in moderate to good yields. Additionally, cyclization of the β-ketoester 1b proceeded efficiently, generating 2b in an 85% yield. Previous work by Rickards and co-workers on a related system reported strong electronic effects when electron-donating substituents were incorporated onto the δ-aryl

True and masked three-coordinate T-shaped platinum(II) intermediates

• Manuel A. Ortuño,
• Salvador Conejero and
• Agustí Lledós

Beilstein J. Org. Chem. 2013, 9, 1352–1382, doi:10.3762/bjoc.9.153

• (II) compounds (with a low spin d8 configuration) for T-shaped structures is due to electronic effects and can be understood from the Walsh diagram shown in Figure 2. The Walsh diagram describes the variation of the L–M–L angle from a T-shaped structure through D3h to a Y-shaped structure. A d8, 14

• equatorial positions in ML3 complexes raises the question of which positions are preferred by the ligands in such compounds. Although in most of the experimentally characterized systems the steric demands dictate the disposition of the ligands, electronic effects are also at work, and they were analyzed for

Synthesis of guanidinium–sulfonimide ion pairs: towards novel ionic liquid crystals

• Martin Butschies,
• Manuel M. Neidhardt,
• Markus Mansueto,
• Sabine Laschat and
• Stefan Tussetschläger

Beilstein J. Org. Chem. 2013, 9, 1093–1101, doi:10.3762/bjoc.9.121

• introduced a different concept to tune melting points in ionic liquids by electronic effects of the aryl substituent [44][45]. However, the mesogenic sulfonimide resulted in the formation of a SmA mesophase only in the case of 3b, while ion pairs 2a,b and 3a did not show any liquid-crystalline properties

Expeditious, mechanochemical synthesis of BODIPY dyes

• Laramie P. Jameson and
• Sergei V. Dzyuba

Beilstein J. Org. Chem. 2013, 9, 786–790, doi:10.3762/bjoc.9.89

• -ethyl-2,4-dimethylpyrrole (Table 2) [13]. The reaction appeared to be insensitive to the electronic effects of the aldehyde, as both electron-donating and electron-withdrawing groups were equally tolerated. The yields were found to be reasonably comparable to those reported in literature (Supporting

Total synthesis and biological evaluation of fluorinated cryptophycins

• Christine Weiß,
• Tobias Bogner,
• Benedikt Sammet and
• Norbert Sewald

Beilstein J. Org. Chem. 2012, 8, 2060–2066, doi:10.3762/bjoc.8.231

• (1.47 Å) lies between the value of a hydrogen substituent (1.20 Å) and an oxygen substituent (1.52 Å). However, despite this similarity in size, a fluorine substituent exerts considerable electronic effects due to the high electronegativity. A trifluoromethyl substituted analogue of epothilone, another

Regioselective synthesis of 7,8-dihydroimidazo[5,1-c][1,2,4]triazine-3,6(2H,4H)-dione derivatives: A new drug-like heterocyclic scaffold

• Nikolay T. Tzvetkov,
• Harald Euler and
• Christa E. Müller

Beilstein J. Org. Chem. 2012, 8, 1584–1593, doi:10.3762/bjoc.8.181

• thioketones 20–22 may be due to electronic effects and prevention of the formation of certain tautomers by the C4-methyl groups in compounds 13–15 [22]. To investigate the influence of the C4-methyl groups on the regioselective thionation reaction, we treated unsubstituted 5,5-dimethylhydantoin 6 with

Organocatalytic asymmetric addition of malonates to unsaturated 1,4-diketones

• Sergei Žari,
• Tiiu Kailas,
• Marina Kudrjashova,
• Mario Öeren,
• Ivar Järving,
• Toomas Tamm,
• Margus Lopp and
• Tõnis Kanger

Beilstein J. Org. Chem. 2012, 8, 1452–1457, doi:10.3762/bjoc.8.165

• increased and the yields were lower with catalyst VII. A methyl substituent slightly decreased the enantioselectivity (Table 3, entry 4). This means that these dependencies cannot be clearly rationalized by the use of the electronic effects of the substituents in the phenyl ring. In the case of squaramide

Sonogashira–Hagihara reactions of halogenated glycals

• Dennis C. Koester and
• Daniel B. Werz

Beilstein J. Org. Chem. 2012, 8, 675–682, doi:10.3762/bjoc.8.75

• crucial part of the solvent mixture, otherwise no reaction was observed. Interestingly, when we employed the perbenzylated enyne 9ea the yield of the alkyne-reduced product decreased tremendously. A mixture of completely reduced products was obtained. Thus, we assume that not only electronic effects, but

Carbohydrate-auxiliary assisted preparation of enantiopure 1,2-oxazine derivatives and aminopolyols

• Marcin Jasiński,
• Dieter Lentz and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2012, 8, 662–674, doi:10.3762/bjoc.8.74

• approximate 1:2 ratio was observed. According to the model proposed in the literature [7][18][20] for the addition of nucleophiles, the stereochemical course is governed by a competition of steric and electronic effects. As presented in Figure 3, the bulky benzyloxy substituent favours the anti-addition and