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1.
Cyclic hexa-para-phenylenesulfide (3c) and tetra-4,4′-biphenyldiyl-sulfide (7) are synthesized for the first time and in surprising yields (up to 65%). Doping with SbF5, leads to conductivities of approx. 10?3 S cm?1, which are discussed with regard to polymeric “PPS”.  相似文献   

2.
According to X-ray crystal structure analyses “cis-benzenetrisimine” (2) and “cis-benzenetrioxide” (1) act as tridentate ligands in their 2:1- and 4:1-complexes 7 (Co(C6H9N3)2(NO3)3) and 8 (Ba(C6H6O3)4(ClO4)2), resp. The latter is the rare example of an organic complex with the (approximate) T-symmetry.  相似文献   

3.
tert-Butyl azidoformate (2) reacts with the conjugate bases of 3a, 7a, 9 (R1 = R2 = CH3), and 9 (R1 = CH3, R2 = H) to give products [4, 8, 12, and 14, respectively] in addition to the expected N-(tert-butoxycarbonyl)indole derivatives.  相似文献   

4.
Synthesis of the two isomers 2, 3 of the mono coenzyme A ester of o-succinylbenzoic acid (1, OSB, i.e. 4-(2-carboxyphenyl)-4-oxobutanoic acid) and enzymic conversion of 3, to 1,4-dihydroxy-2-naphthoic acid 7 shows that as opposed to previous assumptions the “aliphatic” rather than the “aromatic” carboxyl group in o-succinylbenzoic acid 1 is activated during vitamin K2 biosynthesis in Escherichia coli and Mycobacterium phlei.  相似文献   

5.
A short, efficient approach to a key chiral intermediate for the synthesis of pseudomonic acids A and C is delineated.Pseudomonic acids A(1a), B(1b), and C(2) are members of a novel of “C-glycopyranoside” antimicrobial agents which have recently attracted synthetic attetion.2 Presently, we wish to report a short efficient stratedy towards the total synthesis of opticaly active pseudomonic acids. The sequence is highlighted by a novel controlled mono-Claisen rearrangement and a highly regioselective π-allylpalladium mediated displacement.Diacetyl-(L)-arabinal (3)3 was converted to the bis-ketenesilylacetal 4 and warmed to 60°C according to the Ireland ester-enolate Claisen rearrangement method.4 Over a period of ≈5h, smooth conversion to a major rearranged product 5 was observed by 300 MHz NMR. The identity of 5 was confirmed by direct desilylation and methylation (KF, KHCO3, H2O, HMPA, CH3I). After flash chromatography, compound 7 was isolated in 55% overall yield from 3. Careful inspection of the crude methylation product revealed the presence of ≈5% doubly rearranged product 6.The rearrangement of 4 to 5 is a unique example of a selective mono-Claisen rearrangement in which the rate of a second similar Claisen rearrangement (56) is much slower under the reaction conditions. Although the reasons for this interesting selectivity are unclear at this time,5 in practice, the mono-Claisen rearrangement obviates the need for selective differentiation of the two hydroxyl groups, a difficult task at best, in this case.Palladium mediated allylic acetate displacement provided an ideal method for introduction of a second chemodifferentiated side chain with allylic retention and retention of stereochemistry. Alkylation of 7 with sodiothylmalonate using 5 mole % Pd(O)dppe26 was unusually facile (<45 min, 25°C, THF). After semi-preparative HPLC, essentially a single regio- and stereoisomer was isolated in 96% yield.7 Structure 8 was confirmed by extensive 1H-NMR decoupling, as well as an off-resonance 13C-NMR experiment. In particular, H1 (δ 4.53) was coupled vicinally to H6 and H6′ (5 Hz, 8 Hz) and H2 (1.5 Hz), and allylically to H3 (2 Hz). In contrast, H4 (δ 2.78) was coupled to H7 (10 Hz), H5e and H5a (1.8 Hz, 4 Hz), H3 (5 Hz), and H2 (<1 Hz). In addition, H1 and H4 exhibited a small long range coupling constant (J = <1 Hz). The coupling constants rule out
regioisomer 9 and are fully consistent with the indicated conformation, which minimizes 1,3-diaxial-like interactions.Finally, catalytic osmylation of 88 gave a single cis-diol 10 in nearly quantitative yield. Appending of suitably functionalized side chains to provide an enantiocontrolled synthesis of pseudomonic acids A(1a) and C(2) is in progress.9,10  相似文献   

6.
Variable temperature 1H nmr spectrometry has shown that the “unstable” isomer of monodehydro[14]annulene possesses the symmetrical di-trans configuration 1 or 2, and the “stable” isomer (the precursor of [14]annulene) possesses the tri-trans configuration 4.  相似文献   

7.
The synthesis of 3-(β-aminoethyl)benzene oxide (7 is described. The failure of 7 to ring close (78) is attributed to the low “nucleophilic susceptibility” of the arene oxide.  相似文献   

8.
9.
With the aid of nanosecond laser flash photolysis OH is chemically produced and observed “collision free”. The rotational states show inverted population in the A doublets J = 32, 52, 72, and 92 of 2Π32 and anti-i higher rotational states. The intensities of the main and satellite absorption lines further indicate an inversion in special hyperfine states. Application to interstellar OH maser emission is considered.  相似文献   

10.
CW dye laser induced fluorescence emission and thermal emission spectra of YO-molecules in a 1 atm H2O2Ar flame of 2430 K were recorded simultaneously. Narrow band laser excitation was applied to four rotational lines in the (1, 1) Q-branch of the A2Π32X2Σ+ transition and broadband excitation was applied to several separate Q-branches of the A2Π12,32X2Σ+ transitions. From the differences between the fluorescence emission spectra and thermal emission spectra, we conclude that collisional de-excitation of an excited vibronic level takes place by vibrational relaxation, decay to the electronic ground state and by intermultiplet transfer in order of increasing probability.  相似文献   

11.
7-Cyano-7-methylcycloheptatrienes containing one t-butyl group on the 1-position (2) or two t-butyl groups on the 1- and 3-, 1- and 4-, or 1- and 5-positions (3, 4, or 5, respectively) were synthesized and their cyclo- heptatriene (CHT)-norcaradiene (NCD) equilibria measured by variable-temperature 1H NMR for CS2-CD2Cl2 solutions. The 1H NMR chemical shifts of the 7-methyl group indicate that these compounds are composed of essentially one CHT and one NCD tautomer with an endo geometry of the methyl group. The introduction of a t-butyl group at the 1-position of 7-cyano-7-methylcycloheptatriene (1) markedly shifts the equilibrium to the NCD side and the addition of the second t-butyl group further favors the NCD form, with the NCD populations for 2, 3, 4, and 5 at 25 °C 70.9, 96.5, 92.3, and 99.3%, respectively. An application of molecular mechanics (MMPI) calculations to various t-butylated CHT-NCD systems suggests that the t-butyl groups sterically destabilize the CHT form more than the NCD form, bringing about increased NCD populations.  相似文献   

12.
Optical absorption and emission spectra are reported for single crystals of the cubic elpasolite Cs2NaSmCl6. The variable temperature spectra obtained at high resolution are assigned using energies and relative intensities. Transitions from the ground level, 6H52 to cystal fi levels of 6H72-152, 6F12-112, 4G52-92, 4F32,52, 4I92, and 6P32, 52 are located and characterized. Intensity calculations are reported for magnetic dipole allowed transitions. The dominance of vibronic intensity in 6H526F 12-92 and 6P32, 52 transitions is accounted for qualitatively through the ligand polarization model involving quadrupole metal (Sm3+)-ligand (Cl?) interaction mechanisms. The Eu″(6H52)→E′(6H12) Eu′(6F12) no-phonon transition is postulated to be pure electric quadrupole allowed. The ground state magnetic moment is determined to be very small from magnetic circular dichroism (MCD) spectra.This study has led to the assignment of nearly all of the crystal field levels in the visible and IR region for Cs2NaSmCl6. A total of 27 such levels were identified, 17 from no-phonon transitions and the rest from vibronic transitions. The magnetic dipole intensity calculated using intermediate coupling Oh wavefunctions along with a crystal field analysis of the splitting pattern was used in the assignment of the levels. Vibronic bands were observed for all transitions and their vibrational symmetries were tentatively assigned. MCD data were used to determine the magnet moment of the ground state.  相似文献   

13.
2,5-Dimethyl-2,4-hexadiene (1)was studied as a singlet oxygen acceptor in various solvents. 1undergoes concomitantly the three well-known modes of singlet oxygen reactions: (1) the ene-reaction to give the allylic hydroperoxide 3, (2) the (4+2)-cycloaddition to give the endoperoxide 4, and (3) the (2+2)-cycloaddition to give the dioxetane 2. Beyond that (and in contrast to simple olefins), there are (4) “physical” quenching and (5) a “vinylog ene-reaction” to give the twofold-unsaturated hydroperoxide 5. The latter reaction represents a novel mode of singlet oxygen interaction with a substituted 1,3-diene. - Kinetic analysis shows that “physical” quenching, endoperoxide and vinylog ene-product formations proceed with solvent-inde pendent rates; the rates of dioxetane and ene-product formations, however, are solvent-dependent. - A mechanism (Scheme 3) is proposed, according to which endoperoxide formation is due to a concerted singlet oxygen reaction with the s-cis-conformational isomer 1b; with the s-trans-isomer 1a, “physical” quenching and the vinylog ene-reaction proceed via a non-polar singlet diradical intermediate, whereas the ene-product formation occurs via a per epoxide-like transition state. In aprotic solvents, the dioxetane is mainly formed via a “tight-geometry intermediate”, in methanolic solution via a solvent-stabilized zwitterion; the latter is also responsible for the formation of the methanol-addition product 6.  相似文献   

14.
FeIIFeIII2F8(H2O)2 and MnFe2F8(H2O)2, grown by hydrothermal synthesis (P ? 200 MPa, T = 450 or 380°C), crystallize in the monoclinic system with cell dimensions (Å): a = 7.609(5), b = 7.514(6), c = 7.453(4), β = 118.21(3)°; and a = 7.589(6), b = 7.503(8), c = 7.449(5), β = 118.06(3)°, and space group C2m, Z = 2. The structure is related to that of WO3 · 13H2O. It is described in terms of perovskite type layers of Fe3+ octahedra separated by Fe2+ or Mn2+ octahedra, or in terms of shifted hexagonal bronze type layers. Both compounds present a weak ferromagnetism below TN (157 and 156 K, respectively). Mössbauer spectroscopy points to an “idle spin” behavior for FeIIFeIII2F8(H2O)2: only Fe3+ spins order at TN, while the Fe2+ spins remain paramagnetic between 157 and 35 K. Below 35 K, the hyperfine magnetic field at the Fe2+ nuclei is very weak: Hhf = 47 kOe at T = 4.2 K. For MnFe2F8(H2O)2, Mn2+ spin disorder is expected at 4.2 K. This “idle spin” behavior is due to magnetic frustration.  相似文献   

15.
The osmium carbyne complex, Os(CR)Cl(CO)(PPh3)2, (R  p-tolyl) reacts with Group I halides to form the mixed dimetallocyclopropene species, Os(Cul)(CR)Cl(CO)(PPh3)2, Os(AgCl)(CR)Cl(CO)(PPh3)2, Os(AuCl)(CR)Cl(CO)(PPh3)2, and [Os[Ag(OClO3)](CR)Cl(CO)(MeCN)(PPh3)2] ClO4 X-ray crystal structure determination of Os(AgCl)(CR)Cl(CO)(PPh3)2 confirms the presence of a three-membered ring and the structure can be viewed as the “acetylene-like” interaction of an osmium—carbon triple bond with AgCl. In acid solution AgCl is precipitated and an alkylidene complex results from proton addition to the carbyne ligand.  相似文献   

16.
The MIPO3Sm(PO3)3(MI = Li, Na, Ag) systems were studied. Differential thermal analysis and X-ray diffraction were used to investigate the liquidus and solidus relations. Three compounds LiSm(PO3)4, NaSm(PO3)4, and AgSm(PO3)4 were obtained which melt incongruently at 1248, 1143, and 1078 K, respectively. These compounds are isomorphous with their homologs LiLn(PO3)4, NaLn(PO3)4, AgLn(PO3)4 (Ln = Ce, La, Nd). They belong to the monoclinic system. The LiSm(PO3)4 unit cell parameters refined by least squares method are a = 16.43(3) Å, b = 7.16(1) Å, c = 9.65(3) Å, β = 125,9°(1), with the space group C2c and Z = 4. NaSm(PO3)4 and AgSm(PO3)4 are isotypic; they cristallize in the P21c space group, Z = 4; their unit cell parameters are, respectively, a = 12.18(1) Å, b = 13.05(1) Å, c = 7.25(5) Å, β = 126,53°(4), a = 12.25(1)A?, b = 13.06(1) Å, c = 7.201(9) Å, β = 126,57°(7). The ir spectra of the last two compounds indicate that these phosphates are chain phosphates.  相似文献   

17.
The marine triquinane sesquiterpene Δ9(12)-capnellene (1) was synthesised from 2,2,5-trimethyl-5-hexenal (2) by a sequence of all synthetic operations in 5% overall yield. The key steps 3 → 4 → 5 → 6 involve two intramolecular type-I-“Mg-ene” processes.  相似文献   

18.
The synthesis and separation of diastereomere of protected thymidyl(3′–5′)thymidyl 0,0-phosphoranilidate (4) allowed to obtain in the stereospecific manner title compounds 5, whose absolute configuration at P atom was assigned enzymatically. TP(S)T diastereomers (5) were obtained independently via “phosphite” procedure.  相似文献   

19.
Norbornadiene (NBD) is more easily displaced from PtMe2 (NBD) by other ligands than is cyclooctadiene (COD) from PtMe2 (COD). cis-PtMe2L2 (L = py, 12tmen, 12en, NH3, DMSO) have been prepared in this way. cis-PtMe2py2 is very reactive toward oxidative addition. Pyridine can usually be removed from the platinum(IV) products using acid. NBD is even more readily displaced from Pt(CF3)2 (NBD), giving cis-Pt(CF3)2L2 (L = py, 12tmen, 12en, NH3, DMSO, NCR, DMF, CN?, I?, acac?). cis-Pt(CF3)2py2 with CF2I gives fac-Pt(CF3)3py2I.  相似文献   

20.
The addition of “nucleophilic carbene” on 1,2,4-triazole bases (2) and aldehydes is decisively influenced by the anion present. 5-(α-Hydroxyalkyl)-1,2,4-triazolium chlorides, formed in the addition reaction of 3-methylthio-1,4-diphenyl-1,2,4-triazolium chloride (1c) with aldehydes, can be easily reduced to 5-alkyl-1,2,4-triazolium iodides (5). Reduction of these with NaBH4 affords aldehydes by acidic hydrolysis or carboxylic acids by alkaline hydrolysis, the carbon chain of which has been lengthened by one CH2 group, as compared to the starting aldehyde.  相似文献   

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