Synthesis and spectral properties of 6H-2,7,7-trimethyl-4-(o,p-R-phenylamino)-7,8-dihydrofuro[3,2-c]azepines

The preparation of nine novel 6H-2,7,7-trimethyl-4(o-,p-R-phenylamino)-7,8-dihydrofuro[3,2-c]-azepines with possible pharmacological activity is described. The structure of all products was corroborated by ir, ¹H-nmr and ms.     

A convenient synthesis of novel pyrido(1′,2′:1,2)imidazo[5,4‐d]‐1,2,3‐triazinones from imidazo[1,2‐a]pyridines

The imidazo[1,2‐a]pyridine system was investigated as a synthon for the building of very attractive fused triazines, a planar, angular tri‐heterocycle with potential biological activity. Thus ethyl 3‐nitroimidazo[1,2‐a]pyridine‐2‐carboxylate was treated with ammonia or with an excess of primary amines to generate the corresponding substituted nitro carboxamidoimidazopyridines. The nitro substituent in the latter products, was reduced to yield 3‐amino‐2‐carboxamidoimidazo[1,2‐a]pyridine derivatives, which in turn were treated with nitrous acid to furnish 1‐oxo‐2‐substituted pyrido(1′,2′:1,2)imidazo[5,4‐d]‐1,2,3‐triazines.     

A catalyst-free synthesis of asymmetric diaryl ketones from aryltins

A series of diaryl ketones have been synthesized in good yields (40-78%) through the catalyst-free reaction of trimethylarylstannanes with aroyl chlorides in chlorobenzene as solvent. In addition, an attractive feature is that these reactions are completely regioselective making possible the synthesis of diarylketones which are not usually available under the influence of the directing forces of the substituents present in the aromatic ring. Also, the reaction conditions are mild enough to be applied to acid sensitive molecules.     

Facile hydrometalation of alkynes by nido-1,2-(CpRuH)(2)B(3)H(7) yielding novel Ru-B edge-bridging alkylidenes. Stepwise conversion of HCtbd1;CC(O)OMe into nido-1,2-(CpRuH)(2)-3-HOB-4-MeC-5-MeOC-BH(3), Cp = eta(5)-C(5)Me(5)

The reaction of the alkyne HCCC(O)OMe with 7 sep 1,2-(Cp*RuH)2B3H7 leads to hydroboration plus hydroruthenation to produce nido-1,3-mu-Me{C(O)OMe}C-1,2-(Cp*Ru)2B3H7, a compound with an exocluster ruthenium-boron mu-alkylidene that exists in two isomeric forms. Both isomers undergo rearrangement with intramolecular chelation of the carbonyl oxygen at a boron site, thereby opening the cluster and generating arachno-2,3,-mu(C)-5-eta1(O)-Me{C(O)OMe}C-1,2-(Cp*Ru)2B3H7. Further heating leads to deoxygenation of the carbonyl fragment by a boron center concurrent with insertion of the carbon atom into the metallaborane cage to give nido-1,2-(Cp*RuH)2-3-HOB-4-MeC-5-MeOC-BH3.     

不对称Fe-Fe双金属化合物[Cp*Fe(dppe)(C≡CFc))[PF6]n(n=0，1)的合成、结构及光谱性质的研究(英)

A biased bimetallic Fe-Fe complex Cp^*Fe(dppe)(C≡CFc) (1) was synthesized from FcC≡CH (Fc=C₅H₄FeC₅H₅) and Cp^*Fe(dppe)Cl (Cp^*=C₅Me₅). Its one-electron oxidation species [Cp^*Fe(dppe)(C≡CFc)][PF₆] (1a) was also prepared and the spectroscopic properties of 1a was studied. The single-crystal X-ray diffraction analysis of 1 shows that ferrocenylacetylene is bonded at the terminal carbon to the iron center in the Cp^*Fe(dppe) part. Crystallographic data for 1: monoclinic, space group C2/c, with a=4.067 65(14) nm, b=1.260 74(4) nm, c=1.649 89(5) nm, β=104.387(10)°, V=8.195 7(5) nm³, Z=8, D_c=1.354 g·cm^-3, F(000)=3512, μ=0.822 mm^-1. The structure was refined to R₁=0.038 4, wR₂=0.100 0. CCDC: 234893.     

Crystal engineering: Supramolecular structures by cocrystallization ofMeso-1,2-diphenyl-1,2-ethanediol and bisimines,simple cases of molecular recognition

The crystal structures of molecular complexes betweenmeso- 1,2-diphenyl-1,2-ethanediol and two bisimines (N,N-(dibenzylidene)-ethylenediamine and glyoxylidene-bis(2,4-dimethyl-3-pentyl-amine) are reported at different temperatures. The structure-determining motif of the cocrystalline arrangement is one single O-H . N hydrogen bond resulting in infinite ladderlike polymers. The supramolecular structure is formed by recognition of fitting species: Thed- orl-isomers do not arrange in such structures.¹H NMR experiments show that no prearrangements take place by forming complexes in solution.     

Rose Bengal‐Sensitized Photooxidation of the Dipeptides l‐Tryptophyl‐l‐Phenylalanine,l‐Tryptophyl‐l‐Tyrosine and l‐Tryptophyl‐l‐Tryptophan: Kinetics,Mechanism and Photoproducts¶

The Rose Bengal‐sensitized photooxidations of the dipeptides l ‐tryptophyl‐l ‐phenylalanine (Trp‐Phe), l ‐tryptophyl‐l ‐tyrosine (Trp‐Tyr) and l ‐tryptophyl‐l ‐tryptophan (Trp‐Trp) have been studied in pH 7 water solution using static photolysis and time‐resolved methods. Kinetic results indicate that the tryptophan (Trp) moiety interacts with singlet molecular oxygen (O₂(¹Δ_g)) both through chemical reaction and through physical quenching, and that the photooxidations can be compared with those of equimolecular mixtures of the corresponding free amino acids, with minimum, if any, influence of the peptide bond on the chemical reaction. This is not a common behavior in other di‐ and polypeptides of photooxidizable amino acids. The ratio between chemical (k_r) and overall (k_t) rate constants for the interaction O₂(¹Δ_g)‐dipeptide indicates that Trp‐Phe and Trp‐Trp are good candidates to suffer photodynamic action, with k_rlk_t values of 0.72 and 0.60, respectively (0.65 for free Trp). In the case of Trp‐Tyr, a lower k_rlk_t value (0.18) has been found, likely as a result of the high component of physical deactivation of O₂(¹Δ_g) by the tyrosine moiety. The analysis of the photooxidation products shows that the main target for O₂(¹Δ_g) attack is the Trp group and suggests a much lower accumulation of kynurenine‐type products, as compared with free Trp. This is possibly because of the occurrence of another accepted alternative pathway of oxidation that gives rise to 3a‐oxidized hydrogenated pyrrolo[2,3‐b]indoles.     

Effect of the sixth axial ligand in CS-ligated iron(II)octaethylporphyrinates: structural and Mössbauer studies

The effect of a sixth ligand in a series of low-spin thiocarbonyl-ligated iron(II)octaethylporphyrinates has been investigated. Six-coordinate complexes have been synthesized and characterized by M?ssbauer and infrared spectroscopy and single-crystal X-ray structure determinations. The results are compared with the five-coordinate parent complex. The crystal structures of [Fe(OEP)(CS)(1-MeIm)] and [Fe(OEP)(CS)(Py)] are reported and discussed. The 1-methylimidazole and pyridine derivatives exhibit Fe-C(CS) bond distances of 1.703(4) and 1.706(2) A that are significantly longer than the 1.662(3) A reported for five-coordinate [Fe(OEP)(CS)] (Scheidt, W. R.; Geiger, D. K. Inorg. Chem. 1982, 21, 1208). The trans Fe-N(ligand) distances of 2.112(3) and 2.1550(15) A observed for the 1-methylimidazole and pyridine complex are approximately 0.13 A longer than those observed for analogous bis-ligated complexes and are consistent with a significant structural trans effect for the CS ligand. M?ssbauer investigations carried out for five- and six-coordinate thiocarbonyl derivatives with several different sixth axial ligands reveal interesting features. All derivatives exhibit very small isomer shift values, consistent with a very strong interaction between iron and CS. The five-coordinate derivative has delta(Fe) = 0.08 mm/s, and the six-coordinate complexes exhibit delta(Fe) = 0.14 to 0.19 mm/s at 4.2 K. The five-coordinate complex shows a large quadrupole splitting (DeltaE(q) = 1.93 mm/s at 4.2 K) which is reduced on coordination of the sixth ligand (DeltaE(q) = 0.42-0.80 mm/s at 4.2 K). Addition of a sixth ligand also leads to a small decrease in the value of nu(CS). Correlations in structural, IR, and M?ssbauer results suggest that the sixth ligand effect is primarily induced by changes in sigma-bonding. The structure of [Fe(OEP)(CS)(CH(3)OH)] is briefly reported. Crystal data: [Fe(OEP)(CS)(1-MeIm)] crystallizes in the monoclinic system, space group P2(1)/n, Z = 4, a = 9.5906(5) A, b = 16.704(4) A, c = 23.1417(6) A, beta = 100.453(7) degrees. [Fe(OEP)(CS)(Py)] crystallizes in the triclinic system, space group P1, Z = 5, a = 13.9073(6) A, b = 16.2624(7) A, c = 22.0709(9) A, alpha = 70.586(1) degrees, beta = 77.242(1) degrees, gamma = 77.959(1) degrees. [Fe(OEP)(CS)(CH(3)OH)] crystallizes in the triclinic system, space group P1, Z = 1, a = 9.0599(5) A, b = 9.4389(5) A, c = 11.0676(6) A, alpha = 90.261(1) degrees, beta = 100.362(1) degrees, gamma = 114.664(1) degrees.     

Ferromagnetism and chirality in two-dimensional cyanide-bridged bimetallic compounds

The combination of hexacyanoferrate(III) anions, [Fe(CN)(6)](3)(-), with nickel(II) complexes derived from the chiral ligand trans-cyclohexane-1,2-diamine (trans-chxn) affords the enantiopure layered compounds [Ni(trans-(1S,2S)-chxn)(2)](3)[Fe(CN)(6)](2).2H(2)O (1) and [Ni(trans-(1R,2R)-chxn)(2)](3)[Fe(CN)(6)](2).2H(2)O (2). These chiral systems behave as ferromagnets (T(c) = 13.8 K) with a relatively high coercive field (H(c) = 0.17 T) at 2 K. They also exhibit an unusual magnetic behavior at low temperatures that has been attributed to the dynamics of the magnetic domains in the ordered phase.