In this work, the basis sets designed by Clementi, Bunge and Thakkar, for atomic systems, have been used to obtain electronic structure of confined many-electron atoms using Roothaan's approach in Hartree–Fock context with a new code written C, which uses message-passing interface library. The confinement was imposed as Ludeña suggested simulate walls infinity potential. For closed-shell atoms, Thakkar set functions give best total energies (TE) function radius, obtaining following ordering:...

A series of five-, six-, seven-, and eight-membered lactams containing the chiral auxiliary α-methylbenzylamine were structurally analyzed further studied by DFT calculations with purpose to examine detail previously detected intramolecular C-H···O hydrogen-bonding interaction formed between hydrogen atom carbonyl group cyclic amide. The main objective was establish whether its presence does have a tangible relevance in their spatial arrangement solution solid state or is simple not...

Abstract One of the major challenges in organic synthesis is activation or deconstructive functionalization unreactive C(sp 3 )–C(sp ) bonds, which requires using transition precious metal catalysts. We present here an alternative: lactamization piperidines without To this end, we use 3‐alkoxyamino‐2‐piperidones, were prepared from through a dual )–H oxidation, as transitory intermediates. Experimental and theoretical studies confirm that unprecedented occurs tandem manner involving...

The complexes [(η1:η1-ind)(μ-M)R2]2 (R = Me, M Ga (1); R Al (2); Et, B (3)) were prepared by treatment of indazole with MR3 in toluene. These have dimeric molecular structures, the indazolato ligands coordinated a η1:η1 fashion. In solution, 1 and 2 show mixture syn anti isomers 3:5 ratio, respectively; however, solid state can be selectively crystallized toluene benzene. constitute first examples organoaluminum organogallium for which both observed solution crystallized. contrast 2, boron...

In order to understand the influence that position of nitro group on aromatic ring has relative stability two isomers, standard enthalpies formation 3- and 4-nitrophthalic anhydride in gaseous phase, at T = 298.15 K, were obtained by experimental thermochemistry theoretical studies. The crystalline combustion calorimetry sublimation Knudsen method. For calculations, a ab initio molecular orbital method G3 level was used. phase from atomization isodesmic reactions. A study electronic...

Photochemical irradiation of 2,3-dihydro-2-<i>tert</i>-butyl-3-benzyl-4(1<i>H</i>)-quinazolinone produced 3-benzyl-4(3<i>H</i>)-quinazo­linone through photoinduced elimination via a radical mechanism. The use photochemical conditions such as chloroform and UV (λ = 254 nm) got the 3-benzyl-4(3<i>H</i>)-quinazolinone in high yield. Some theoretical calculations were achieved to explain mechanism presence intermediates was confirmed by trapping with different...

The intramolecular hydrogen bond of the N-H···S type has been investigated sparingly by thermochemical and computational methods. In order to study this interaction, standard molar enthalpies formation in gaseous phase diphenyl disulfide, 2,2'-diaminodiphenyl disulfide 4,4'-diaminodiphenyl at T = 298.15 K were determined experimental methods calculations. gas-phase obtained from crystalline sublimation. Enthalpies using rotatory bomb combustion calorimetry. By thermogravimetry, vaporization...

In this work, we determine, both experimentally and computationally, structural thermochemical properties of the methyl 2- 4-methoxybenzoates. Combustion vaporization enthalpies these compounds were obtained through combustion calorimetry thermogravimetry. From properties, their standard molar formation in gas phase, at T = 298.15 K, also determined. addition, computed gas-phase 2-, 3-, 4-methoxybenzoates using composite method Gaussian G4, atomization reactions, a weighted Boltzmann...

Abstract The selective and dual C(sp3)–H oxidation of N-heterocycles to their corresponding 3-alkoxyamino lactams mediated by TEMPO oxoammonium cation (TEMPO+) is turning into a convenient nonmetallic strategy for the rapid functionalization piperidines pyrrolidines bioactive alkaloids. Mechanistic proposal suggests that TEMPO+ prefers oxidize endocyclic C–Hα bond either N-substituted or iminium intermediates, which are transformed enamine then trapped cation. Although product formation...

The TEMPO oxoammonium cation has been proven to be both an efficient oxidizing reagent and electrophilic substrate frequently found in organic reactions. Here, we report that this versatile chemical can also used as promoter for C- N-glycosylation reactions through a Ferrier rearrangement with moderate high yields. This unprecedented reactivity is explained terms of Lewis acid activation glycal by

Recently, strong evidence that supports the presence of an intramolecular C-H···O hydrogen bond in amides derived from chiral auxiliary α-methylbenzylamine was disclosed. Due to high importance this asymmetric synthesis, inadvertent interaction may lead new interpretations upon stereochemical models which is present. Therefore, a series lactams containing (from three eight-membered ring) were theoretically studied at MP2/cc-pVDZ level theory with purpose studying origin and nature C-Hα···O...

The chemistry of (S)-methyl xanthates derived from xylo- and ribo-furanose derivatives in the presence stannyl radical is investigated. Xanthate β-xylo-furanose affords exclusively a deoxygenated product; whereas, under same reaction conditions, α-ribo-furanose xanthate derivative produces quantitatively hemithioacetal compound. We reasoned that case derivative, favorable β-oxygen effect Barton-McCombie deoxygenation operating where, according to theoretical calculations, unusual molecular...

The stereocontrolled synthesis of naturally occurring products containing a 5,5-spiroketal molecular structure represents major synthetic problem. Moreover, in previous work, the cephalosporolide E (ceph E), which presumably was obtained from its epimer congener F) through an acid-mediated equilibration process, reported. Consequently, we performed theoretical investigation to provide relevant information regarding title question, and it found that higher thermodynamic stability ceph E,...