BIOTRANSFORMATION OF 2α，5α，10β，14β－TETRA－ACETOXY－4（20），11－TAXADIENE BY THE FUNGIJS CUNNINGHAMELLA ECHINULATA

?5α,10β,14β-Tetra-acctoxy-4(20).11-taxadicne (1) could be regioselectively transfonnedinto 6α 10β-dihydroxy-2α,5α,14β-triacetoxy-4(20). 11- taxadiene (2) by Cunninghamella echinnlata infair yield. 6βM.10β-Dihydroxy-2α,5α,14β-triacet 11-taxadienc (3). 10β-hydroxy-2α,5α,14β-triacetoxy-4(20).11-taxadiene (4), 10 β-hyboxy-4β,20-epoxy -2α,5α,14β-triacetoxy- tax - 11- ene (5)asminor prpducts were also isolated

Synthesis and Crystal Structure of 4-Chloro-N-(2-(2-nitrophenyl)acetoxy)-N-(m-tolyl)benzamide

The new title compound 4-chloro-N-（2-（2-nitrophenyl）acetoxy）-N-（m-tolyl）benza- mide （C：2HI7C1N2Os, Mr = 424.82） has been synthesized via the reaction of 4-chloro-N-hydroxy-N- （m-tolyl）benzamide with 2-（2-nitrophenyl）acetyl chloride. The structure of the product was confirmed by 1H NMR, 13C NMR, IR, HRMS （ESI） and single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, space group P21/c with a = 13.0269（10）, b =6.7251（6）, c = 23.9313（16） A, β = 99.931（6）°, V = 2065.1（3） A3, Z = 4, Dc = 1.366 g/cm3, F（000） = 880,μ = 0.221 mm-1, the final R = 0.0600 and wR = 0.1754 for 1981 observed reflections （I〉 20（/））. X-ray analysis indicates that the chloro-phenyl ring （C（10）℃（15）） and the methyl-substituted benzene ring （C（16）℃（21）） are not coplanar with the nitro-substituted benzene ring （C（1）--C（6））, with the dihedral angle to be 70.78° and 63.72°, respectively. Hydrogen bonds C（2）-H（2）...O（2） and C（7）-H（7B）...O（5） are observed.

Stereoselective synthesis of (5R,6S)-6-acetoxy hexadecanolide——The major component of the oviposition attractant pheromone of the mosquito Culex pipens fatigans and its enantiomer from L-glutamic acid

A concise synthesis of the mosquito oviposition attractant pheromone, (-)-(5R, 6S)- and (+)-(5S 6R)-6-acetoxy hexadecanolide from L-glutamic acid is described. The key steps are the inversion of the configuration at C-4 of 7, and the formation of δ-lactone from the γ-lactone through ring enlargement.

Intramolecular energy transfer between chromophores separated by a rigid steroid bridge——Ⅰ.Singlet and triplet energy transfer in 3β(1-naphthyl)acetoxy-⊿~5-androsten-17-one

Intramolecular transfer of both singlet and triplet electronic excitation between the naphthalene moiety and the carbonyl group in 3β-(1-naphthyl)acetoxy-⊿~5-androsten-17-one was studied.Irradiation with 280 nm light selectively leads to excitation of the naphthalene moiety. Transfer of the singlet excitation from the naphthalene moiety to the carbonyl group occurs by dipole- dipole resonance interaction.The measured rates for such energy transfer in several solvents agree with that calculated from Frster equation.After efficient intersystem crossing,the carbonyl group transfers triplet excitation back to the naphthalene moiety via electron exchange mechanism.The combination of singlet and triplet energy transfer with the high efficiency of intersystcm crossing of carbonyl group results in the phosphorescence enhancement of naphthalene moiety.

New 9,19-cycloartane triterpenoid from the root of Cimicifuga foetida

AIM: To study the 9, 19-cycloartane triterpenes from the roots of Cimicifuga foetida. METHOD: Chromatographic separations by silica gel, C18 reversed phase silica gel, and high-performance liquid chromatography(HPLC) were used. All of the structures were elucidated on the basis of spectroscopic analysis and chemical methods. RESULTS: Five 9, 19-cycloartane triterpenes,(3β, 12β, 15α, 24R)-12, 2'-diacetoxy-24, 25-epoxy-15-hydroxy-16, 23-dione-3-O-α-L-arabinopyranoside(1), actein(2), 23-epi-26-deoxyactein(3), asiaticoside B(4), and 12β-hydroxycimigenol(5) were isolated from the roots of Cimicifuga foetida. CONCLUSION: Compound 1 is a new triterpene with two acetoxy groups at C-2' and C-12.

STUDIES ON SYNTHESIS OF GIBBERELLIN II——PARTIAL SYNTHESIS OF GIBBERELLIN A_5 METHYL ESTER

Gibberellin A5 （GA5） （9） is a C19-gibberellin which was originally isolated from Phaselous mutiflorus in 1960 by MacMillan et al. This letter reports the synthesis of Gibberellin A5 methyl ester（8） from Gibberellic acid （1）.