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The alkylating as well as alkoxylating behavior of dialkyl sulfites are well presented in the literature. In the present work dialkyl sulphites behavior has been investigated towards EOSIN Y (tetrabrominated fluorescein). The products of the reactions (dialkylated eosin Y) reveal that alkylation takes place at the both active sites (at hydroxyl and carboxyl functionalities) in a single step through sulphur-centred Arbuzov type rearrangement. Density functional theory (DFT) has been used as a tool to analyze the role of the halogen groups present at the periphery of the xanthene moiety in alkylation at hydroxyl and carboxy positions of EOSIN Y. Furthermore, in photo-physical study, it was observed that compound C acts as a superoxide sensor specifically with the detection limit 63μM. Its anti-microbial activity was checked against the E. coli and S-aureus using the agar well diffusion assay and, it was observed that it could be used as better antimicrobial agent. [ABSTRACT FROM AUTHOR]

Herein, we have developed a new route towards the enantioselective synthesis of chiral amines without any chiralcatalyst through SN2 nucleophilic substitution reaction of 5-dichloromethyl-4-difluoromethylene-2,3-dimethyl-3,4-dihydro-quinazoline [A] with methylamine using Density Functional Theory (DFT) framework. DFT results reveal that the formation of both the enantiomers are exothermic in nature. The activation energy for R- and S-enantiomer comes out to be 52.02 and 37.15 kcal/mol respectively. Also, the bond distance of hydrogen bonding (N1–H-----F–C=C–) in S-enantiomer comes out to be 2.10 Ǻ which is not feasible in R-enantiomer. Thus, the free energy profiles and structural parameters along the reaction coordinates provide enough evidence to conclude that amination will result in the enantioselective formation of S-enantiomer and this stereoselectivity is accredited to intramolecular H bonding (N–H-----F–C = C–) involved in the transition state corresponding to the formation of S-enantiomer. To the very best of our information, this is the first report proposing enantioselectivity in SN2 reaction without any chiral catalyst/chiral auxiliary through intramolecular hydrogen bonding. [ABSTRACT FROM AUTHOR]

The present study explores various quantum chemical models to better understand the molecular properties of pyridylselenium compounds. We have carried out theoretical and experimental analyses of bis(3,5-dimethyl-2-pyridyl)diselenide (1), 3,5-dimethyl-2,6-bis(methylselenenyl) pyridine (2) and 3,5-dimethyl-2-(methylselenenyl)pyridine (3). The study demonstrates the effect of structural variations on molecular properties of these compounds. Density functional theory (DFT) has been used to calculate vibrational wavenumbers and intensity of vibrational bands and the results obtained are in excellent agreement with the experimental FT-IR data. The1H and13C NMR chemical shifts were calculated using GIAO method in gas phase and solvent phase of CDCl3by taking IEFPCM method and correlations have been developed which accurately predicts the chemical shift values of various organoselenium compounds. The HOMO-LUMO energies in the gas and solvent phase were calculated by using B3LYP/6-311++G(d,p) level of theory. The HOMO-LUMO energy gaps in different molecules were compared and correlated with their biological activity. [ABSTRACT FROM PUBLISHER]

N-Benzylthiazolidine-2-thione is the key for the synthesis of pharmaceutically important compounds. A novel route for the synthesis of N-benzylthiazolidine-2-thione through of CS2 with N-benzylaziridine in the presence of 1,3-di-tert-butylimidazolium-2-dithocarboxylate ( catalyst I) has been proposed by reliable computations performed within the formalism of density functional theory. The mechanism of the proposed reaction is similar to the of tertiary aziridines and using a recyclable catalyst that is reported to provide access to 3-substituted 2-oxazolidones with excellent yield. Because the rate determining step needs to surmount a high energy barrier, the reaction route has been deciphered in high boiling solvent (1, 2-ethanediol). The highlight of the mechanistic route detailed here is that the proposed pathway is a cyclic process that is exothermic in nature with the regeneration of the catalyst and involves simple reagents. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

• Selective lithiation of 2,4-lutidine with LDA and LDEA has been studied. • Transition states of LDA and LDEA determine the selectivity in these reactions. • LiCl changes selectivity of the LDA mediated lithiation of 2,4-lutidine and its BF 3 complex. • Et 2 NH reverses the regioselectivity of an LDA mediated reaction. The lithiation of 2,4-lutidine (1) with non-nucleophilic bases, such as lithium diisopropylamide (LDA) and lithium diethylamide (LDEA) affords different regioisomers under similar reaction conditions. The mechanism of these reactions and the factors determining selectivity have not been well understood. The present endeavor explores experimental and quantum chemical approaches to investigate factors that determine regioselectivity of the reaction. It has been found that transition states of LDA/LDEA determine regioselectivity and the presence of acatalyst (LiCl) plays a vital role. The LDA mediated lithiation of 1 proceeds through a disolvated open dimer of LDA, leading to a 2-methyl lithiated product. LDEA mediated lithiation is dominated by a route involving interception of 1 with a trisolvated monomer-based transition state of LDEA resulting in a 4-methyl lithiated product. The mechanism is supported by LiCl catalyzed reactions. LiCl has also been found to effect a change in selectivity of the lithiation of BF 3 -complexed 2,4-lutidine. Image, graphical abstract [ABSTRACT FROM AUTHOR]