Synthesen von Heterocyclen, 130. Mitt.: Über das Glomerin und das Arborin

Zusammenfassung Es werden einstufige Synthesen desGlomerins (2) [1,2-Dimethyl-4(1H)-chinazolinon] und desArborins (3) [1-Methyl-2-benzyl-4(1H)-chinazolinon] bekanntgegeben.

---

Syntheses of heterocycles, CXXX: Glomerine and arborine

A one step synthesis ofglomerine (2) [1.2-dimethyl-4(1H)-quinazolinone] andarborine (3) [1-methyl-2-benzyl-4(1H)-quinazolinone] is described.

     

Yeast protein farnesyltransferase. Binding of S-alkyl peptides and related analogues

[reaction: see text] Protein farnesyltransferase (PFTase) catalyzes alkylation of cysteine residues by farnesyl diphosphate (FPP). The dissociation constants for the PFTase-peptide analogue complexes for the series of analogues fl-RTRC(X)VIA (X = H, methyl, dodecyl, farnesyl) were measured by fluorescence anisotropy. The results indicate that an ionizable sulfhydryl moiety is important for substrate binding and the farnesyl group in the product facilitates binding.     

Hydroformylation and hydrocarbethoxylation of 1,2-dicarbethoxy-1,2,3,6-tetrahydropyridazine and 1,2-dicarbethoxy-1,2,3,4-tetrahydropyridazine

The unsaturated compounds 1,2-dicarbethoxy-1,2,3,6-tetrahydropyridazine 1 and 1,2-dicarbethoxy-1,2,3,4-tetrahydropyridazine 2 have been hydroformylated and hydrocarbethoxylated in the presence of some well known cobalt, rhodium, palladium and platinum catalysts. The hydroformylation reaction can be tuned by a suitable choice of the catalyst precursor and reaction conditions, thus allowing the synthesis with high selectivity of one of the two possible isomeric aldehydes. The carbonylation reaction is less synthetically useful, since it shows low activity and unsatisfactory chemo- and regio-selectivity. However, the ester 1,2,4-tricarbethoxyhexahydropyridazine 10 can be prepared in good yield from olefin 1 by using the complex [PdCl₂(PPh₃)₂] as the catalyst precursor.     

A CNDO/INDO crystal orbital model for transition metal polymers of the 3d series—basis equations

The crystal orbital formalism in the tight-binding approximation is combined with a recently developed CNDO/INDO model for transition metal species of the 3d series in order to allow band structure calculations on the Hartree-Fock (HF) SCF level for one-dimensional (1D) chains with organometallic unit cells. The band structure approach based on the CNDO and INDO approximation can be used for any atom combination up to bromine under the inclusion of the 3d series. The matrix elements for the tight-binding Hamiltonian are derived for an improved CNDO and INDO framework. The total energy of the 1D chain is partitioned into one-center contributions and into two-center increments of the intracell and intercell type. Semiempirical band structure calculations on simple model systems are compared with available ab initio data of high quality.     

Interaction of heavy metal ions with ammonium humates

Sorption properties of ammonium humates with respect to Fe(III), Cu(II), Al(III), Ni(II), Pb(II), and Zn(II) are studied. The effect of the metal ion concentration on the ammonium humate consumption is examined and the corresponding dependences are analyzed using regression equations. The IR spectra of brown coal humic acids, ammonium humates, as well as Fe, Cu, Ni, Zn, Pb, and Al humates are presented.     

Synthesis of(E)7-[[2-[4-(m-trifluoromethylphenoxy)-3α and 3β-hydroxy-1-butenyl]-5-oxo-1 -pyrrolidinyl]]heptanoic acids

The synthesis of an 8-aza-PGE₁ analog, (E)-7-[[2-[4-(m-trifluoromethylphenoxy)-3α and 3β-hydroxy-1-butenyl]-5-oxo-pyrrolidinyl]]heptanoic acids is reported.     

Alkaline hydrolysis of the natural lignin of cottonplant stems in the presence of anthraquinone

The study of a three-stage alkaline hydrolysis of the natural lignin of cottonplant stems has shown that the bulk of the lignin undergoes fragmentation during stage I. The addition of anthraquinone leads to an appreciable increase in the yield of low-molecular-mass hydrolysis products.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 743–748, September–October, 1996. Original article submitted March 1, 1993.     

Overlapping spheres multiple scattering Xα calculations of the ionization potentials and electron affinities of nitrogen oxides

The ionization potentials and electron affinities of a series of nitrogen oxygen compounds have been calculated by the overlapping spheres MS Xα method to assess its applicability on a series for which good experimental data is available. The results for the ionization potentials were satisfactory although a straightforward matching of calculated and experimental IP's without consideration of other criterion would have led to some misassignments. The results for the electron affinities are in excellent agreement with experiment.     

On low temperature fluorescence of perylene crystals

At low temperatures, the broad excimer fluorescence band of α-perylene crystals is replaced by a weakly structured emission at higher energy. This emission originates from a new crystal state (Y-state) which is populated independently of the high temperature excimer (E-state). Due to the temperature dependence of its first order decay rate and due to the thermally activated formation of the E-state, the Y-emission grows rapidly at temperatures below 90 K. The Y-emission differs from the fluorescence of the monomeric β-perylene at 5.5 K by its Stokes shift of 1300 cm^?1, the lack of vibronic structure, the long first order decay time of 40 ns and the absence of bimolecular annihilation indicating a localized state. The Y-state is attributed to a less relaxed pair state formed upon contraction of the dimeric crystal lattice.