Three new sesquiterpenes with cytotoxic activity from Dobinea delavayi.

Three new sesquiterpenes dobinins A-C (1-3), together with five known compounds, were isolated from the root of Dobinea delavayi. The structures of the three new compounds were determined on the basis of spectroscopic analysis including 1D-, 2D-NMR and MS techniques as well as by comparison of the spectral data with those of analogous compounds reported in the literatures. Compounds 1-3 were screened for antitumor activity in vitro and exhibited definite cytotoxic activity against the human tumor cell line HL-60 with IC50 levels of 8.0 × 10-5, 4.7 × 10-5, and 5.1 × 10-5 M, respectively.

Methyl 7-oxo-12-propyl-amino-13-nitro-deisopropyl-dehydro-abietate.

In the title compound, C(21)H(28)N(2)O(5) (systematic name: methyl 1,4a-dimethyl-7-nitro-9-oxo-6-propyl-amino-1,2,3,4,4a,9,10,10a-octa-hydro-phenanthrene-1-carboxyl-ate) the cyclo-hexane ring (A) and the central cyclo-hexene ring (B) exist at a trans ring junction, with the two methyl groups in the axial positions of the six-membered rings. Ring A has a chair conformation and ring B a half-chair conformation. An intra-molecular N-H⋯O hydrogen bond occurs. The crystal structure is stabilized by inter-molecular C-H⋯O and N-H⋯O inter-actions.

[TDHF study of electronic absorption spectrum of (mu-L1) (mu-L2)-decacarbonyl triosmium].

Ab initio method was used to optimize the molecular geometry for a series of clusters (mu-L1) (mu-L2)- decacarbonyltri-osmium [L1, L2 = H, Cl, Br, I] at HF/CEP-4G level. The related chemical properties of clusters, in particular, the regularities of the bridge halogen effects on spectroscopic properties and bonding properties were discussed. The calculation results of the frontier molecular orbital showed that M-M bonds were mainly composed of s and d atomic orbitals. From Cl to I, with the atom number of bridge ligand increasing, HOMO and NHOMO orbitals on the Os3(CO)10 (mu-L)2 clusters and HOMO on the Os3 (CO)10 (mu-H) (mu-L) clusters become higher, while deltaepsilonL-H and deltaepsilon-NH energies become lower, so the authors predicted that the electronic absorption bands of clusters are shifted to infrared region. Excited states of clusters calculated with TDHF show that the transition of cluster Os3(CO)10 (mu-H)2 (I) is mainly 7 --> sigma* and sigma --> sigma*, while the electronic absorption of other clusters Os3 (CO)10 (mu-H) (mu-L) [L = Cl, Br, I] and Os3(CO)10 (mu-L)2 [-L = Cl, Br] is mainly from sigma --> sigma* transition. From Cl to I, with the atom number of bridge ligand increasing, the electronic absorption band of cluster is shifted to infrared region, and also the absorption becomes weaker.

[Theoretical calculation of vibrational frequencies for clusters of (1,2-micro2-L1)(1,2-micro2-L2)-decacarbonyltriosmium [L1, L2=H, Cl, Br, I]].

Density functional theory (DFT) and ab initio method have been employed to optimize the molecular geometry of (1,2-micro2-H) (1, 2-micro2-L) Os3 (CO)10 (L: Cl, Br, I) at B3LYP/CEP-4G, B3LYP/LanL2DZ, RHF/CEP-4G and RHF/LanL2DZ levels, respectively. By using ab initio method, the authors have optimized the molecular geometry of (1,2-t12 -L)2 Os3 (CO)20 (L: H, Cl, Br, I). The calculations showed that the charge was translated from Os(CO)3 to Os(CO)4. Harmonic vibrational analysis was performed at the RHF/CEP-4G levels, and according to the frequencies and intensities of the equilibrium structure obtained by using ab initio method, the IR spectra of structure have been simulated. The calculated results were compared with each other and with available experimental data, and were discussed in detail.

Regio- and Diastereoselective Allenylation of Aldehydes in Aqueous Media: Total Synthesis of (+)-Goniofufurone(1).

The regio- and diastereoselectivities of metal-mediated allenylation of carbonyl compounds were investigated in aqueous media. Different metal mediators showed varied regioselectivities on product formation during propargylation-allenylation reactions of carbonyl compounds with simple propargyl bromide. Under the standard reaction conditions, the use of indium provided the highest regioselectivity, with a preference of formation of the homopropargyl alcohol. The use of tin and bismuth as the metal mediator provided slightly lower selectivities with the same preference. The use of zinc and cadmium as the mediators further lowered the product selectivity. The reactions of an aliphatic aldehyde with simple propargyl bromide showed a lower selectivity than the reaction of an aromatic aldehyde in most cases, except for the use of tin or zinc (where comparable selectivities were observed). On the other hand, the reaction of terminal-substituted propargyl bromides with aldehydes mediated by indium showed a high regioselectivity in forming allenylation products. The indium-mediated allenylation of carbonyl compounds bearing an alpha-hydroxyl group also proceeded with a high diastereoselectivity, forming syn-diols predominantly in aqueous ethanol. The high diastereoselectivity in allenylation of alpha-hydroxyl-substituted aldehydes was attributed to the chelation effect exhibited by the alpha-hydroxyl substitutent. Through the use of this highly diastereoselective allenylation, (+)-goniofufurone was synthesized from D-glucurono-6,3-lactone.

Manganese-Mediated Carbon-Carbon Bond Formation in Aqueous Media: Chemoselective Allylation and Pinacol Coupling of Aryl Aldehydes.

The use of manganese as a mediator for allylations and pinacol couplings in aqueous media was investigated. The combination of manganese and copper is found to be a highly effective mediator for the allylation of aryl aldehydes in water. Such a combination is found to be more reactive than other previously reported metals in aqueous media. No reaction was observed with either manganese or copper alone as the mediator. Only a catalytic amount of copper is required for the proceeding of the reaction. The uses of Cu(0), Cu(I), and Cu(II) as the copper source are all effective. The use of a catalytic amount of manganese combined with a stoichoimetric amount of copper led to the failure of the reaction. Allyl chloride is found to be more effective than allyl bromide for the corresponding reaction. The use of substituted allyl halides gave a mixture of regio- and diastereoisomers. Aromatic aldehydes reacted chemoselectively in the presence of aliphatic aldehydes. An exclusive selectivity was also observed when both an aliphatic and an aromatic aldehyde functionalities are present in the same molecule. In the presence of acetic acid or ammonium chloride, manganese was found to effect the pinacol-coupling reaction in water. The reaction proceeds selectively with aryl aldehydes.