Stereochemistry of the synthesis of 2,9-dimethyl- and 1,2,9-trimethyldecahydro-4-quinolones and some of their hydroxy derivatives

Individual 2,9-dimethyl- and 1,2,9-trimethyldecahydro-4-quinolones were isolated by separation of mixtures of the stereoisomers. The stereochemistry of reactions involving the addition of hydrogen, acetylene, and organomagnesium compounds to the carbonyl group was studied. The structure of the 2,9-dimethyl- and 1,2,9-trimethyldecahydro-4-quinolones and the corresponding amino alcohols were established on the basis of their IR and PMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No, 6, pp. 796–804, June, 1977.     

Determination of the three-dimensional orientation of the hydroxyl group in st ere oisomeric 1, 2, 7- trimethyl- and 1,2-dimethyl-7-tert-butyldecahydro-4-quinolols and their 4-ethynyl-substitut ed derivatives by IR spectroscopy

The three-dimensional orientation of the hydroxyl group in stereoisomeric 1,2,7-trimethyl- and 1,2-dimethyl-7-tert-butyldecahydro-4-quinolols and their 4-ethynyl-substituted derivatives was established by IR spectroscopy. The possibility of a twist conformation of the heteroring in 1,2,7-trimethyl- and 1,2-dimethyl-7-tert-butyldecahydro-4-quinolols with an equatorial hydroxyl group is shown.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 379–382, March, 1976.     

Infrared spectroscopy of the intramolecular hydrogen bond in acethylacetone: a computational approach

The intramolecular hydrogen bond in the enol-acethylacetone (ACAC) is investigated by performing reduced-dimensional quantum calculations. To analyze the shared proton vibrations, two sets of coordinates were employed: normal mode coordinates describing the motion in the vicinity of the most stable configuration, and internal coordinates accounting for the double minimum proton motion. It is proved that the extreme broadness of the OH-stretch band in ACAC is a consequence of the coexistence of two enol-ACAC structures: the global minimum and the transition state for rotation of the distal methyl group. Further, a ground-state tunneling splitting of 116 cm(-1) is found, and it is shown that the inclusion of the kinematic coupling is mandatory when treating large-amplitude proton motion. In the OH-stretch direction a splitting of 853 cm(-1) was predicted.     

Investigation of the structure of 2h,6h-2,6-dimethyl-4-amino-1,3,5-dithiazine by IR spectroscopy

It was established by IR spectroscopy that 2H,6H-2,6-dimethyl-4-amino-1,3,5-di-thiazine exists in the amino form in carbon tetrachloride at low concentrations.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1050–1053, August, 1981.     

Investigation of the stereochemistry of N-substituted 2,5-dimethyl-4-piperidinones by NMR spectroscopy

The conformations of the cis and trans isomers of N-substituted 2,5-dimethyl-4-piperidinones were studied by means of the¹H and¹³C NMR parameters. It was established that in the case of bulky and electron-acceptor substituents attached to the N atom the cis isomers are virtually completely represented by the chair (2a,5e) conformation, while the trans isomers are characterized by the chair (2e,5e) twistboat (2a,5e) chair (2a,5a) conformational equilibrium. It is demonstrated that 1-tert-butyltrans-2,5-dimethyl-4-piperidinone hydrochloride has the twist (2a,5e) conformation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1760–1768, August, 1990.     

The IR absorption spectra and spatial structure of the stereoisomeric 1, 2, 5-trimethyl-4-hydroxypiperidyl-4-carbinols

The spatial structure of the geometric isomers of some 1, 2, 5-trimethyl-4-hydroxypiperidyl-4-carbinols is investigated with the aid of IR spectroscopy, and their spatial configurations and conformations are explained by analysis of the intramolecular hydrogen bonding.     

Cooperative intramolecular hydrogen bond and conformations of thiocalix[4]arene molecules

The joint FTIR spectroscopic study and ab initio quantum-chemical calculations (HF/3-21G and PBE/TZ2P methods) showed that thiocalix[4] arene molecules adopt the cone conformation in CCl₄ solutions. The weakening of the cooperative intramolecular H bond in thiocalix[4]arenes compared to the corresponding calix[4]arenes can be due to the larger thiocalixarene macrocycle, bifurcated hydrogen bond in it, and electron density transfer from the bridging S atom to the benzene ring.     

IR and NMR spectra, intramolecular hydrogen bonding and conformations of mercaptothiacalix[4]arene molecules and their para-tert-butyl-derivative

It is demonstrated that the introduction of p-tert-butyl groups dramatically influences the conformational behaviour of the mercaptothiacalix[4]arene molecules. Quantum-chemical computations in combination with IR and NMR spectroscopy prove that, in contrast to closely related calixarenes, the 1,3-alternate becomes a dominant conformer of p-tert-butyl-mercaptothiacalix[4]arene not only in crystal, but also in solutions and in vacuum. It is shown that the title molecules form essentially non-cooperative intramolecular hydrogen bonds: their SH groups are intramolecularly H-bonded solely to the sulfide groups bridging thiophenolic units. The enthalpy of this bonding, evaluated from Iogansen’s rule, amounts to ca. 1.5 kcal mol⁻¹ per one SH···S bond, which about four times smaller than the enthalpies of cooperative intramolecular H-bonds formed by related calixarenes and thiacalixarenes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Dipole moment,isomerization, and intramolecular hydrogen bond in some benzene derivatives (computations)

The dipole moment vectors of some benzene monoderivatives are calculated to test the method used in an attempt to explain the dipole moments of o-, m- and p-substituted phenols (X-C₆H₄-OH; X = -OH, -F, -NO₂, -CHO, -COOH, -CH₃). The vectors seem to include contributions from a mixture of planar conformers whose populations obey a Boltzmann-type distribution. The calculated intramolecular interaction moment is proposed as a simple criterion indicating the strength of the intramolecular hydrogen bond in o-phenols.     

An investigation of intramolecular hydrogen bonds and the spatial conformations of the stereoisomeric α-oxoalcohols of the cyclohexane,piperidine, and decahydroquinoline series

The influence of the conformation of the geometric isomers of 1-acetyl-4-tert-butylcyclohexan-1-ol and of 4-acetyl-1, 2-dimethyldecahydroquinoline on the nature of the intramolecular hydrogen bonds has been studied by IR spectroscopy, and on the basis of the results obtained the configurations and conformations of the geometric isomers of the 4-acyl-1,2,5-trimethylpiperidin-4-ols have been established.Conformational stability of the stereoisomers of ketols of the piperidine series has been found.It has been shown that the geometric isomers of each of the compounds studied with axially orientated acyl groups exist in solutions in the form of an equilibrium mixture of two rotameric forms. The enthalpy of an intramolecular hydrogen bond in these compounds is 0.5–0.7kcal/ mole.     

Reinvestigation of intramolecular hydrogen bond in malonaldehyde derivatives: An ab initio,AIM and NBO study

The RAHB systems in malonaldehyde and its derivatives at MP2/ 6‐311++G(d,p) level of theory were studied and their intramolecular hydrogen bond energies by using the related rotamers method was obtained. The topological properties of electron density distribution in O? H···O intramolecular hydrogen bond have been analyzed in term of quantum theory of atoms in molecules (QTAIM). Correlations between the H‐bond strength and topological parameters are probed. The results of QTAIM clearly showed that the linear correlation between the electron density distribution at HB critical point and RAHB ring critical point with the corresponding hydrogen bond energies was obtained. Moreover, it was found a linear correlation between the electronic potential energy density, V(r_cp), and hydrogen bond energy which can be used as a simple equation for evaluation of HB energy in complex RAHB systems. Finally, the similar linear treatment between the geometrical parameters, such as O···O or O? H distance, and Lp(O)→σ*_OH charge transfer energy with the intramolecular hydrogen bond energy is observed. © 2010 Wiley Periodicals, Inc., Int J Quantum Chem, 2011     

Investigation of the mobility of methylene group hydrogen atoms in some derivatives of 2-iminothiazolidin-4-one

A study is made of the reaction of 2-arylamino- and 3-aryl-2-arylimino derivatives of thiazolidin-4-one with p-[N, N-di(2-chloroethyl)amino]benzaldehyde and p-nitroso-N, N-di(2-chloroethyl) aniline. It is shown that replacement of hydrogen at the endocyclic nitrogen atom of 2-iminothiazolidine-4-one raises mobility of hydrogen atoms in the methylene group in the order phenyl > p-tolyl > > benzyl. The results obtained are confirmed by IR spectroscopy.     

Localized orbital studies of hydrogen bonding: III. The intramolecular hydrogen bond in 4-methylimino 2-pentanone

Geometry optimizations using the INDO molecular orbital method are carried out on the three possible isomeric forms of 4-methylimino- 2-pentanone. It is found that the molecule strongly prefers a structure containing a hydrogen-bonded chelate ring. Of the two possible isomers containing an intramolecular hydrogen bond, only the structure with the chelated proton closer to the oxygen corresponds to an energy minimum, although the energy surface connecting these two isomers is very flat. The results are interpreted using experimental and calculated NMR properties and energy localized molecular orbitais.     

Investigation of the surface of Ni-Pd catalysts by IR spectroscopy

The reaction of carbon monoxide with the surface of Ni, Pd, and Ni-Pd catalysts, deposited on -Al₂O₃, was investigated at 25°C by IR spectroscopy in conjunction with an adsorption volumetric technique. The IR spectra contained the following absorption bands (v, cm^–1): 2020–2100 (AB1) (linear and subcarbonyl forms of adsorbed CO); 1945–1985 (AB2) (bridging); 1920–1940 (AB3) with a shoulder at 1870–1885 (AB4) (bridging and many-center). In the spectrum of Ni the absorption band AB5 appears at 1770–1780 (CO-Ni⁺). It appears with surface coverage a 1.3 mole CO/mole M. The optical density (A) of AB1 for Ni₉₇Pd₃ is appreciably higher than for the other investigated samples. In the Ni-Pd catalysts the intensity of AB2 in relation to AB1 is higher than in nickel. The introduction of K⁺ ions into the support of the bimetallic sample reduces the optical density of AB1. In modified Ni-Pd-K the AB3 and AB4 bands disappear.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1276–1282, June, 1992.