Ferrocene Compounds. XXVII. Synthesis and Structure of 2-(Ferrocenylmethyl)propane-1,3-diol

The title compound was obtained by reduction of diethyl (ferrocenylmethyl)malonate with lithium aluminium hydride in diethyl ether. The structure of this novel ferrocene derivative was assigned by means of elemental analysis, IR, [¹H]NMR, and [¹³C]NMR spectroscopy. The structure was also confirmed by a single crystal X-ray study. The compound crystallizes in monoclinic P2₁/a space group with unit cell dimensions: a = 9.7360(6), b = 27.040(5), c = 14.767(3) Å, = 103.835(6)°, V = 3774.8(11) ų, Z = 12. The asymmetric unit contains three crystallographically independent molecules. In the ferrocenyl moieties, the Fe–C bond distance values are in the range 2.006(5)—2.051(3) Å and C–C distances in the range 1.366(7)–1.425(4) Å. The cyclopentadienyl rings in each of the molecules are mutually twisted by about 13° from the eclipsed conformation. The hydroxyl groups are involved in the intermolecular O–H...O hydrogen bond formation with O-O distances in the range 2.686(3)–2.801(4) Å forming infinite two-dimensional network in a [0 0 1] plane. The crystal structure is additionally stabilized by C–H-O weak intermolecular hydrogen bonds.     

Tautomerism of 2-amino-2-oxazolin-4-ones. II

The study of the tautomerism of 2-amino-2-oxazolin-4-one ( 1 ) and its methyl derivatives has been completed. The methylation of 1 gave 2-imino-3-methyloxazolidin-4-one ( 4 ) and 2-methyl-amino-2-oxazolin-4-one ( 7 ). All attempts to isolate O-methyl derivatives failed. The uv, nmr, ir, and Raman spectra led to the definite conclusion, in agreement with the chemical evidence, that the 2-aminooxazolinic form a , if it is theoretically possible, predominates in all compounds investigated. Otherwise the 2-iminooxazolidinic form b predominates. The assignment of the carbonyl stretching is discussed on the basis of ir and Raman data. The nmr spectrum of compound 7 shows anomalous behaviour, most probably due to the existence of a monomer-dimer equilibrium.     

Semi-analytic time-marching algorithms for semi-linear parabolic equations

New time marching algorithms for numerical solution of semi-linear parabolic equations are described. They are based on the approximation method proposed by the first author. An important feature of the algorithms is that they are both explicit and stable under mild restrictions to the time step, which come from the non-linear part of the equation.     

Synthesis and structure of <Emphasis Type="Italic">N</Emphasis>-substituted (1-ferrocenylethyl)amine derivatives

N-Acetyl-(1-ferrocenylethyl)amine (8) was synthesized by N-acylation of (1-ferrocenylethyl)amine (7) in 84% yield. Reaction of N-acetyl-[1-(1′-bromo-ferrocenyl)ethyl]amine (4) (which was prepared by multistep sequence starting from bromoferrocene) with n-BuLi/ClCOOEt gave 77% of N-acetyl-N-ethoxycarbonyl-(1-ferrocenylethyl)amine (6) instead of the expected ethyl 1′-[1-(acetamido)ethyl]ferrocene-1-carboxylate (5). Both structures were undoubtedly confirmed by (HR)MS spectroscopy and single crystal X-ray structure analysis.     

Analysis of volatile sesquiterpenoids in environmental and geological samples

In order to evaluate vloatile compounds, especiallly sesquiter-penoids, in environmental and geological samples a method was penoids, in environmental and geological samples a method was required to characterize these components when they occur at low concentrations. After fractionation of the total sample extracts by TLC the aliphatic fractions were analyzed by HRGC AND THE kovats indices of all resolved peaks were calculated and comkpared with indices of all resolved peaks were calculated and compared with those obtained for commercial standards. As final step, the fractions were analyzed by HRGC-MS and structures confirmed by comparison of their mass spectra with those of certified sesuiterpene standards. Additionally sesquiterpenoids present in the dissolved phase in water samples were concentrated by solid phase extraction using XAD-2 resin. In this initial study, recovery tests with the resin were carried out in order to evaluate its performance rather than validating the methodology.     

Ferrocene-dipeptide conjugates derived from aminoferrocene and 1-acetyl-1′-aminoferrocene: synthesis and conformational studies

In this study we present the synthesis and conformational analysis of mono- and disubstituted ferrocene bioconjugates bearing dipeptide chains (Boc-AA-AA-Fn-X, AA=Gly, l-Ala, l-Val). The conformational preferences of novel aminoferrocene derived conjugates with X=H, as well as their 1-acetyl analogues (X=COMe), were investigated by spectroscopic techniques (IR, NMR and CD) and corroborated by DFT calculations. Chirally organized structures, stabilized through intrachain hydrogen bonds, prevail in solution when X=H. The resulting 10-membered hydrogen-bond ring is destabilized by heteroannular introduction of an acetyl group when X=COMe.     

Action of hydrogen peroxide on some 2-aminooxazoles and imidazolin-2-ones. Isolation of hydroperoxyimidazolidin-2-ones

The reaction of some 2-aminooxazoles and imidazolidin-2-ones with hydrogen peroxide afforded stable trans-β-hydroxyhydroperoxy- or dihydroperoxyimidazolidin-2-ones according to the reaction conditions. In the case of 3a-hydroxy-7a-hydroperoxyoctahydro-2H-benzimidazolidin-2-one, the trans isomer is forbidden and cis adduct was isolated. A radical pathway to these hydroperoxides is proposed. From 2-amino-4-methyloxazole and hydrogen peroxide 2-amino-2-hydroxy-4-methyloxazolidin-4-yl peroxyacetate was also isolated.     

Asymmetric cyclopropanation reactions catalyzed by carbohydrate-based crown ethers

Optically active cyclopropane derivatives were prepared by a novel, simple and green approach in high enantioselectivities using monosaccharide-based chiral crown ethers as phase transfer catalysts. The crown ethers having d-glucopyranoside, d-mannopyranoside and d-altropyranoside units proved to be efficient catalyst in a few asymmetric phase transfer cyclopropanation reactions. The Michael-initiated ring closure (MIRC) reactions of diethyl bromomalonate with chalcones took place with complete diastereoselectivity and up to 99% ee. Using benzylidenemalononitrile, 2-arylidenemalononitriles, 2-benzylidene-1,3-indandione, substituted 2-benzylidene-1,3-indandiones, 2-arylidene-1,3-indandiones and 2-benzylidene-1,3-diphenyl-1,3-propanediones enantioselectivities up to 92%, 99%, 54% 93%, 89% and 72%, respectively, were achieved, in the presence of chiral lariat ethers derived from different monosaccharides. The absolute configuration of a cyclopropane diester product was determined by a combined CD spectroscopic and theoretical study.