Substituent effect on the energy barrier for σ-bond formation from π-single-bonded species, singlet 2,2-dialkoxycyclopentane-1,3-diyls

• Jianhuai Ye,
• Yoshihisa Fujiwara and
• Manabu Abe

Beilstein J. Org. Chem. 2013, 9, 925–933, doi:10.3762/bjoc.9.106

• diradicals. Thus, the aryl substituent was introduced at C(1), C(2), or/and C(3) positions of the diradicals DRd–g, and the substituent effects on the lifetime of the singlet diradicals were compared with the lifetime of a phenyl-group-substituted diradical DRc and the parent diradical DRa. The laser flash

Kinetics and mechanism of the anilinolysis of aryl phenyl isothiocyanophosphates in acetonitrile

• Hasi Rani Barai and
• Hai Whang Lee

Beilstein J. Org. Chem. 2013, 9, 615–620, doi:10.3762/bjoc.9.68

• ). The kinetic results of the present work are discussed based on the selectivity parameters and deuterium kinetic isotope effects (DKIEs). The aim of this work is to gain further information on the substituent effects, DKIEs and mechanism of the phosphoryl transfer reactions. Results and Discussion

• substituent effects of X on the reaction rates are not compatible with a typical nucleophilic substitution reaction. The Hammett and Brönsted plots with X are biphasic concave upwards with a break region between X = H and 4-Cl (break point of σX ≈ 0.13), giving unusual positive ρX and negative βX values with

• X = 4-Cl and 3-Cl. Positive ρX (and negative βX) values indicate that the nucleophilic N atom becomes more negative in the TS compared to in the ground state (GS). The substituent effects of Y on the reaction rates are consistent with a typical nucleophilic substitution reaction, and the rate

An efficient and practical entry to 2-amido-dienes and 3-amido-trienes from allenamides through stereoselective 1,3-hydrogen shifts

• Ryuji Hayashi,
• John B. Feltenberger,
• Andrew G. Lohse,
• Mary C. Walton and
• Richard P. Hsung

Beilstein J. Org. Chem. 2011, 7, 410–420, doi:10.3762/bjoc.7.53

• (135 °C), thereby implying an accelerated process of electrocyclization. This feature is consistently observed in related ring-closures of 1,3,5-hexatrienes with an electron-donating substituent at the C3 position of the triene [94][95][96][97][98][99] (for theoretical studies on substituent effects on

Effects of anion complexation on the photoreactivity of bisureido- and bisthioureido-substituted dibenzobarrelene derivatives

• Heiko Ihmels and
• Jia Luo

Beilstein J. Org. Chem. 2011, 7, 278–289, doi:10.3762/bjoc.7.37

• ) rearrangement [27][28] of dibenzobarrelene (dibenzobicyclo[2.2.2]octatriene) (1a) and its derivatives has been shown to be an appropriate model reaction for the assessment of substituent effects on the selectivity of organic photoreactions (Scheme 1) [29][30]. The photoreactivity of dibenzobarrelene derivatives

Heavy atom effects in the Paternò–Büchi reaction of pyrimidine derivatives with 4,4’-disubstituted benzophenones

• Feng-Feng Kong,
• Jian-Bo Wang and
• Qin-Hua Song

Beilstein J. Org. Chem. 2011, 7, 113–118, doi:10.3762/bjoc.7.16

• observations with those of systems of 1a (with electron-donating groups, EDGs), and 1b and 1f (also with EWGs). However, as a heavy atom effect, observations above can be rationalized based on the triplet mechanism of the Paternò–Büchi reaction. Results and Discussion Substituent effects To investigate

• substituent effects of benzophenones in the Paternò–Büchi reaction, photochemical reactions of DMT/DMU with 1a–f in acetonitrile-d3 were performed in Pyrex NMR tubes. The regioselectivity (the ratio of 2/3) and the yield were measured directly from the 1H NMR spectra of crude product mixtures and are listed

• benzophenones generate two series of regioisomeric oxetanes, 2 and 3, via 1,4-diradical intermediates, and reveal notable substituent effects on the regioselectivity and the photochemical efficiency. The reactions initiated by triplet benzophenones with EDGs give a higher proportion of 2 and a lower

β-Hydroxy carbocation intermediates in solvolyses of di- and tetra-hydronaphthalene substrates

• Jaya S. Kudavalli and
• Rory A. More O'Ferrall

Beilstein J. Org. Chem. 2010, 6, 1035–1042, doi:10.3762/bjoc.6.118

• -hydroxy-1,2-dihydronaphthalene. Rate constants for solvolysis of cis- and trans-1-trichloroacetoxy-2-methoxy-1,2-dihydronaphthalene (3) in acetonitrile-water mixtures at 25 °C. Solvolysis reactions: oxygen substituent effects on reactivitya. Supporting Information Supporting Information File 144

Redox-active tetrathiafulvalene and dithiolene compounds derived from allylic 1,4-diol rearrangement products of disubstituted 1,3-dithiole derivatives

• Filipe Vilela,
• Peter J. Skabara,
• Christopher R. Mason,
• Thomas D. J. Westgate,
• Asun Luquin,
• Simon J. Coles and
• Michael B. Hursthouse

Beilstein J. Org. Chem. 2010, 6, 1002–1014, doi:10.3762/bjoc.6.113

• -dithiole-2-thione and TTF derivatives, postulate a likely reaction mechanism and comment on substituent effects. Results and Discussion Synthesis Scheme 1 summarises the overall procedure that leads to the 1,4-aryl rearrangements. The lithiation of compound 1 with LDA and subsequent reaction with aryl

Donor-acceptor substituted phenylethynyltriphenylenes – excited state intramolecular charge transfer, solvatochromic absorption and fluorescence emission

• Ritesh Nandy and
• Sethuraman Sankararaman

Beilstein J. Org. Chem. 2010, 6, 992–1001, doi:10.3762/bjoc.6.112

• these molecules is relatively non-polar and devoid of significant solvent and substituent effects. By contrast, the fluorescence emission bands of 1a–g showed significant substituent and solvent effects. The fluorescence emission spectra of 1a–g in cyclohexane, and DMSO are shown in Figure 2. In

Solvent-free and time-efficient Suzuki–Miyaura reaction in a ball mill: the solid reagent system KF–Al₂O₃ under inspection

• Franziska Bernhardt,
• Ronald Trotzki,
• Tony Szuppa,
• Achim Stolle and
• Bernd Ondruschka

Beilstein J. Org. Chem. 2010, 6, No. 7, doi:10.3762/bjoc.6.7

• activity in the Suzuki–Miyaura reaction under ball milling conditions. In addition to the reactivity of the substrates (substituent effects), the activity of the as-prepared KF–Al2O3 strongly depends on the residual water content. The extent of water influence on the performance of the coupling reaction