First synthesis of 1,5-diazabicyclo[3.1.0]hexane complexes with cadmium salts

Complexes of bicyclic diaziridines 6,6′-bi(1,5-diazabicyclo[3.1.0]hexane) (L ¹ ) and 6-(4-methoxyphenyl)-1,5-diazabicyclo[3.1.0]hexane (L ² ) with the salts Cd(NO₃)₂ · 4H₂O and Cd(ClO₄)₂ · 6H₂O have been synthesized. The fact of complexation has been established by cyclic voltammetry. The crystal structure of complex L ¹ with Cd(NO₃)₂ (the coordination number of cadmium is 8) has been studied by X-ray diffraction.     

Design,synthesis and antiproliferative activity of novel 2,7-disubstituted triazolo[1,5-a]pyrimidines

In our efforts to identify novel potent anticancer agents, we synthesized a series of 2,7-disubstituted triazolo[1,5-a]pyrimidines (6–16). Their antiproliferative activity against Bel-7402, HT-1080 and WI-38 cell lines was tested by MTT assay in vitro. Four of the compounds (9–11 and 16) displayed promising antiproliferative activity superior to gefitinib, especially compound 9. A preliminary SAR study of these derivatives was performed.     

One-step synthesis of substituted 3,5-dinitropiperidines and 1,5-dinitro-3,7-diazabicyclo[3.3.1]nonanes from 1,3-dinitropropanes

1,5-Dinitro-3,7-diazabicyclo[3.3.1]nonane derivatives were synthesized in up to 83%yields by the Mannich reaction of 1,3-dinitropropanes with excess formaldehyde and primary amines. In some cases, for instance, when 2,2-dimethyl-1,3-dinitropropane and benzylamine or monoethanolamine are used, the reaction occurs with low yields or stops at the step of formation of 3,5-dinitropiperidines. The influence of the structure of the starting compounds and reaction conditions on the yields of 1,5-dinitro-3,7-diazabicyclo[3.3.1]nonanes and 3,5-dinitropiperidines was studied.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 405–411, February, 2005.     

Synthesis of cis-1,5-Dimethyl-2,4-dinitro-2,4-diazabicyclo[3.1.0]hexan-3-one and cis-1,5-dimethyl-2,4-dinitro-2,4-diazabicyclo[3.2.0]heptan-3-one

cis-1,5-Dimethyl-2,4-dinitro-2,4-diazabicyclo[3.2.0]heptan-3-one and cis-1,5-dimethyl-2,4-dinitro-2,4-diazabicyclo[3.1.0]hexan-3-one were both synthesized in three steps each from a common precursor, 1,3-diacetyl-4,5-dimelhyl-4-imidazolin-2-one.     

A novel [60]fullerene amino acid for use in solid-phase peptide synthesis

[see structure]. A fullerene derivative containing a free amino group has been condensed with N-Fmoc-L-glutamic acid alpha-tert-butyl ester to give a C60-functionalized amino acid. The carboxylic end of this amino acid has been deprotected in acidic conditions, and the resulting acid has been used for solid-phase peptide synthesis. The final peptide, cleaved from the resin, was very soluble in water solutions and showed antimicrobial activity against two representative bacteria.     

Heterocycles from amino acids. A novel synthetic approach for imidazo[1,5-a]pyridines and imidazo[1,5-a]quinolines

From the corresponding heterocyclic amino acids 2 and 9a the heterocyclic systems imidazo[1,5-a]pyridine ( 3 ) and imidazo[1,5-a]quinoline ( 10 ) are easily accessible. From compound 7 the tricyclic system 11 was prepared and from compound 17a a pyridyl-1,2,4-triazinone ( 18 ) could be obtained.     

Convenient synthesis of novel pyrimido[4,5-b][1,5]benzothiazepines

Reaction of 4,6-dichloropyrimidine-5-carbaldehyde with amines in chloroform gave 4-(substitutedamino)-6-chloro-pyrimidine-5-carbaldehydes derivatives at low temperature. Treatment of the latter products with 2-aminobenzenethiol in alkaline benzene and then in boiling acetonitrile gave a novel group of 11H-pyrimido[4,5-b][1,5]benzodiazepine derivatives. Structures of the products confirmed by ¹HNMR, IR, and mass spectra.     

A novel synthesis of pyrido[2,3-b][1,5]benzodiazepines

A novel and convenient synthesis of the title compounds 4, 5, 11 , and 13 is described, involving the ring transformation of 1,5-benzodiazepine derivatives 1a and 1b with active methylene compounds.     

Molecular structure of 1,5-diazabicyclo[3.1.0]hexane as determined by gas electron diffraction and quantum-chemical calculations

The equilibrium molecular structure and conformation of 1,5-diazabicyclo[3.1.0]hexane (DABH) has been studied by the gas-phase electron-diffraction method at 20 degrees C and quantum-chemical calculations. Three possible conformations of DABH were considered: boat, chair, and twist. According to the experimental and theoretical results, DABH exists exclusively as a boat conformation of C s symmetry at the temperature of the experiment. The MP2 calculations predict the stable chair and twist conformations to be 3.8 and 49.5 kcal mol(-1) above the boat form, respectively. The most important semi-experimental geometrical parameters of DABH (r(e), A and angle)e), deg) are (N1-N5) = 1.506(13), (N1-C6) = 1.442(2), (N1-C2) = 1.469(4), (C2-C3) = 1.524(7), (C6-N1-C2) = 114.8(8), (N5-N1-C2) = 107.7(4), (N1-C2-C3) = 106.5(9), and (C2-C3-C4) = 104.0(10). The natural bond orbital (NBO) analysis has shown that the most important stabilization factor in the boat conformation is the n(N) --> sigma*(C-C) anomeric effect. The geometry calculations and NBO analysis have been performed also for the bicyclohexane molecule.     

A practical chromatography-free synthesis of a 5,6-dihydroimidazolo[1,5-f]pteridine derivative as a polo-like kinase-1 inhibitor

A practical chromatography-free synthesis of a potent polo-like kinase-1 inhibitor possessing a unique 5,6-dihydroimidazolo[1,5-f]pteridine structure has been developed. We showed that key cyanoimidazole ring formation could be conducted at benign temperature and obtained a chiral 5,6-dihydroimidazolo[1,5-f]pteridine derivative in good yield without epimerization. An aniline derivative containing a trans 1,4-cyclohexyl diamine structure was prepared by a synthesis that makes use of defined stereocenters of commercially available trans-cyclohexane-1,4-diamine via selective piperazine ring formation from a primary diamine. A coupling reaction of the 3-chloro-5,6-dihydroimidazolo[1,5-f]pteridine derivative and the aniline derivative in the endgame was closely investigated, and good yields were achieved both by palladium-catalyzed amination and acid-promoted coupling under benign reaction conditions. As a result of these investigations, the polo-like kinase-1 inhibitor was successfully obtained in a practical way without concern for generation/separation of stereoisomers.     

Reaction and sensing of octafluorocyclopentene with 1,5-diazabicyclo[4,3,0]non-5-ene

Reactions of octafluorocyclopentene (C₅F₈) with 1,5-diazabicyclo[4,3,0]non-5-ene (DBN) are studied by analyses of an isolated product and optical spectra from the viewpoint of applications to gas-sensors. Obtained results suggest that nucleophilic reactions of DBN proceed toward the double bond of C₅F₈ molecule accompanied with hydroxide anion attack on carbon-fluoride bonds of C₅F₈ moiety under ambients, forming unique C₅F₈-modified adducts. The present reaction is conducive to a new type of technologies for quick and selective sensing that can be used to develop alarm systems in the field of the environment and etching processing factories.     

First synthesis of 2,6-diazabicyclo[3.2.0]heptane derivatives

The first synthesis of 6-phenyl-2,6-diazabicyclo[3.2.0]heptane 1 and its orthogonally protected precursor 2 is herein reported. Our strategy enables to chemically address the two nitrogen atoms of 2,6-diazabicyclo[3.2.0]heptane core individually and selectively, thus allowing rapid access to several subsets of widely substituted fused azetidines.     

Stereoselective synthesis of dipeptide beta-turn mimetics: 7-benzyl and 8-phenyl substituted azabicyclo[4.3.0]nonane amino acid esters

A stereoselective method has been developed for the synthesis of 7- and 8-substituted dipeptide beta-turn mimetic azabicyclo[4.3.0]nonane amino acid esters. The allyl groups were introduced in high diastereoselectivity, controlled by 3-phenyl or 4-benzyl groups in pyroglutamic acid derivatives 3 or 9, respectively. The precursors, dehydroamino acids 7 and 13 derived from 5 or 11, underwent asymmetric hydrogenations with Burk's DuPHOS Rh(I)-based catalysts to furnish alpha-amino acid derivatives in high stereoselectivity. The resulting amino acids 8 and 14 were converted to the beta-turn mimetics 6,5-bicyclic lactams 1a-d in high yields.