Synthesis of aza steroid analogs

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 854–855, June, 1991.     

Synthesis of aza analogs of 2-aminocheomone

Aza analogs of 2-aminochromone 3- 2-amino-4-oxo-4H-pyrano [2,3-b]pyridine and 2-amino-4-oxo-4H-pyrano [3,2-c]pyridine 3- were synthesized. It was established from the PMR and IR spectra that these compounds exist in the amino ketone form.     

Conformational flexibility of 1,3-cyclohexadiene and its aza analogs

The conformational flexibility of 1,3-cyclohexadiene and its analogs — pyridine and pyrimidine derivatives— was studied by HF/6-31G** ab initio quantum chemical calculations. The potential surface calculations and normal vibration shape analysis show that the molecules exhibit two weakly coupled ring deformation modes. One of the modes may be described as rotation around the C(sp₃)-C(sp₂) bond leading to a transition state of the ring inversion process. The other mode involves flattening of the butadiene fragment and a loss of planarity for endocyclic double bonds without any pronounced changes in the conformation of the saturated part of the molecule. An accurate calculation of the ring inversion barrier demands inclusion of electron correlation effects. Translated fromZhurnal Strukturnoi Khimii, Vol. 41, No. 3, pp. 474-479, May-June, 2000.     

Reactions and mass-spectrometric study of aza analogs of 2-aminochromone

Electrophilic substitution reactions at the C and N(₂) atoms of 2-amino-4-oxo-4H-pyrano[2,3-b]pyridine were studied, 2-Aminoazachromones were subjected to a massspectroscopic study in comparison with 2-aminochromenes, and fundamental differences in their fragmentation were established.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1477–1483, November, 1976.     

A novel method for the synthesis of sulfur substituted-cyclopyrophosphate of cADPR analogs

A facile and efficient protocol for the synthesis of sulfur substituted-cyclopyrophosphate of cIDPRE(P_S~1-cIDPRE) was developed.The key step was the cyclization process which was completed by the sulfur substituted cyclization precursor 1b via the one-pot phosphoramidite strategy.     

New synthesis of pipecolic acid and analogs

Pipecolic acid congeners are synthesised from α-cyanoamides, obtained by substitution of α-methoxyamides with trimethylsilyl cyanide in an alternative route via oxidation of amidoalkylationproducts of the α-methoxyamides.     

New method for the synthesis of tetrathiofulvalene

A new method for the synthesis of tetrathiofulvalene is presented, and conditions for the synthesis of its complex with 7,7,8,8-tetracyanoquinonedimethane are described.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 338–339, March, 1976.     

New method for the synthesis of azolidones

A new method for the synthesis of azolidones by direct condensation of chloroacetic acid and aromatic amines was developed. sym-Dialkylureas are formed in the case of aliphatic amines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 87–89, January, 1978.     

New method for the synthesis of indenes

A new two-step method was developed for the synthesis of 2-sulfonyl-substituted indenes from aromatic aldehydes. The reactions of 1-phenylsulfonyl-1-(trimethylsilyl)ethylene with ortho-lithiated derivatives of aromatic and heteroaromatic aldehydes afford conjugate addition products whose subsequent cyclization gives substituted 2-sulfonylindenes in preparative yields. The reactions of 2-(phenylsulfonyl)indenes with Grignard reagents were studied. It was shown that the sulfonyl group can be replaced in the presence of iron(iii) acetylacetonate.     

New method for the synthesis of tetrachlorothiophene

The reaction of tetrachloroethylene with hydrogen sulfide at 450–500 °C leads to the formation of tetrachlorothiophene as the principal product, along with hexachlorobutadiene, the yield of which increases as the reaction temperature is raised. Communication 15 from the series “High-Temperature Organic Synthesis.” See [1] for communication 14. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 310–311, March, 1980.     

Effects of inductive substituents on electronic spectra aza analogs of fluoranthene

The conditions under which the Hückel molecular orbital (HMO) treatment of inductive substituent effects can be expected to be reliable are discussed from the viewpoint of the Pariser-Parr-Pople (PPP) model. The HMO theory fails to predict correctly the direction of the shift of the first intense band in the ultraviolet spectrum of fluoranthene (1–1 transition) on 3-aza substitution. Calculations on the five azafluoranthenes using the simple version of the PPP method suggest that this is due to strong mixing of hydrocarbon states by the effect of the substituent and predict significant changes in energies, intensities, and polarizations of fluoranthene electronic transitions on aza substitution. Transition moment directions derived from dichroic absorption of 3-azafluoranthene in stretched polyethylene sheets are in agreement with PPP predictions. Arguments are given against a previous assignment of the first transition in 1-azafluoranthene as n- ^*.

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Zusammenfassung Aus der Sicht des Pariser-Parr-Pople-Modells (PPP) werden die Bedingungen diskutiert, unter denen die HMO-Behandlung induktiver Substituenteneffekte als zuverlässig erscheint. Die HMO-Theorie ist nicht in der Lage, die Verschiebung der ersten intensiven Bande im UV-Spektrum des Fluoranthens (1–1-Übergang) bei 3-Aza-Substitution richtig vorauszusagen. Berechnungen an den 5 Azafluoranthenen nach der einfachen PPP-Methode lassen vermuten, daß diese Tatsache durch eine starke Vermischung von Kohlenwasserstoffzuständen — hervorgerufen durch die Wirkung des Substituenten — bedingt ist. Die PPP-Methode sagt ferner beträchtliche Änderungen in den Energien, Intensitäten und Polarisationen der Elektronenübergänge des Fluoranthens voraus, wenn man im Fluoranthen eine Aza-Substitution vornimmt. Die Richtungen des Übergangsmoments, die aus der dichroitischen Absorption des 3-Azafluoranthens in langgestreckten Polyäthylenschichten abgeleitet werden können, stimmen mit den Voraussagen von PPP-Berechnungen überein. Es werden Argumente vorgebracht, die gegen eine Kennzeichnung des ersten Übergangs in 1-Azafluoranthen als n- ^*-Übergang sprechen.

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Résumé On discute à l'aide du modèle de Pariser-Parr-Pople (PPP) les conditions de validité du traitement par la méthode de Hückel (HMO) des effets de substituants inductifs. La méthode de Hückel ne peut prédire correctement la direction du déplacement de la première bande intense du spectre UV du fluoranthène (dite transition «1–1») dans les substitutions aza en 3. Les calculs sur 5 azafluoranthènes à l'aide de la méthode PPP ordinaire suggèrent que cet échec est du à un fort mélange des états de l'hydrocarbure sous l'effet du substituant, et prédit des changements importants dans les énergies, les intensités et les polarisations des transitions du fluoranthène par les substitutions aza. Les directions des moments de transition déduits de l'absorption dichroïque du 3 aza fluoranthène dans des feuilles de polyéthylène étiré sont en accord avec le calcul PPP. On apporte des objections à la caracterisation antérieure de la 1 ère bande du 2 azafluoranthène comme une bande n- ^*.

     

Stabilization of polyheteroatomic aza and phospha analogs of cyclobutadiene and benzene

A method is proposed for the stabilization of polyheteroatomic rings consisting only of nitrogen or phosphorus atoms by introduction of acceptors of the unshared electron pair of the heteroatom, particularly oxygen atoms, with the formation of oxide forms. The positions of introduction of the acceptor groups into four- and six-membered rings were determined. The conclusions drawn were confirmed by calculations by the MNDO method of tetrazete 1,3-dioxide and 1,3-ylid and hexaphosphorine 1,3,5-trioxide and 1,3,5-ylid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 250–255, February, 1988.