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Plant cell suspension cultures of Taxus brevifolia and Taxus globosa were used as biocatalysts on an exogenous racemic substrate in order to determine the influence of several parameters on its configurational deracemization bioactivity. Taxus brevifolia demonstrated a directly proportional relationship between the enantiomeric ratio (er) [1] and the time of reaction, yielding a mixture of 90(S):10(R) after 7 days. Pure enantiomers were tested and the results showed that the (S)-enantiomer remained intact, whereas the (R)-enantiomer was biotransformed. The buffer solution did not present any effect. Sucrose and temperature modified the reaction time and the er. The pH was a critical variable in relation to the age of the suspension cultures. Taxus globosa showed a low efficiency for distinguishing between the enantiomers.

Calluses from seasonal mature shoots of Taxus globosa Schltdl. were subcultured in new medium containing 1 mg l -1 NAA, 0.5 mg l -1 2, 4-D, 0.025 mg l -1 BA. Calluses growing for 30 and 40 days in a medium added with 0.1-5.0 mg l -1 of chlorocholine chloride (CCC) were harvested for determination of taxol, phenolic compounds, and for polyphenol oxidase (PPO) activity. The results showed that by increasing the CCC concentration, callus growth was decreased, phe- nolic level was raised up, but taxol content and PPO activity changed differently. The highest taxol production (0.0269 mg g -1 dry weight callus) and PPO activity (4.53 U g -1 fresh weight callus) were achieved at day 40 with a medium containing 0.5 mg l -1 CCC. Possible reason of higher taxol level stimulated by CCC is discussed in the text.

Cultured plant cells from Taxus brevifolia Nutt and Taxus globosa Schltdl were investigated as biocatalysts using exogenous substrates. Production of highly specific metabolites by these species prompted us to analyse their synthetic potential. Whole cells suspensions have the capacity to chemoselectively reduce ethyl acetoacetate to ethyl 3-hydroxybutyrate chemo- and stereoselectively reduce rac-2-benzoylcyclohexanone to (1R, 2S)- and (1S, 2S)-2-hydroxycyclohexylphenylmethanones, and to cyclize N-phthaloyl-L-glutamine to thalidomide.

The costunolide lactone, a sesquiterpene compound isolated from Zaluzania triiloba species, reacted with several dihalocarbene sources produced by trihaloform-NaOH under successive phase transfer reactions yielding mono-, bis- and tris-dihalocyclopropane adducts. The structures, as well as the configurational assignments of the different derivatives, were established by 1H and 13C NMR spectroscopy and assisted by X-ray crystallographic and molecular modelling studies. The specific shielding of protons in the neighbourhood of different halogens on the cyclopropane moieties was correlated to the pseudocontact interactions.

The reaction of the 6‒amino‒1,3‒dimethyl uracil with the arylidenketones1–4, enabled us to obtain adducts whose structures result from nucleophilic attack and self condensation, yielding with monomeric, dimeric or trimeric derivatives obtained with moderate (40–50%) yields. The reaction was induced by the uracil derivative and the role of this reagent was that of a nucleophile and oligomerization promoter. The structures obtained in this study were mainly elucidated with 1D and 2D high resolution NMR experiments.

In the solid state, trans-2,6-diphenyl-4-(hydroxyimino)-piperidinol, C 17 H 18 N 2 O 2 , (1), trans-2,6-bis(1-methyl-pyrrol-2-yl)-4-(hydroxyimino)piperidinol, C 15 H 20 N 4 O 2 , (2), and trans-2,6-bis(thien-2-yl)-4-(hydroxyimino)-piperidinol, C 13 H 14 N 2 O 2 S 2 , (3), adopt conformations with an axial OH substituent on the ring N atom, in contrast to the preference for an equatorial conformation in solution. Molecules of all three structures are held together in chains by hydrogen bonding.

The Stereoselective addition of the pyrimidine derivative 1 to the exocyclic methylene of the α,β unsaturated dehydrocostus lactone 2, Ivalin acetate 3 and Zaluzanin A diacetate 4, was achieved resulting in a new C-C bond formation. In the cases of compounds 3 and 4, after the addition, the lactone was cleaved followed by reclosure into a lactam ring system.

Irradiation of the pyrazoline derivative of O-methylisoperezone (4) by ultraviolet light yielded the rearrangement products 5,6 and 7.

Substituted bromomethyl- and chloromethylbenzenes and bis(bromomethyl) benzenes were directly converted, in high yields, to the corresponding methyl- and isopropyl- benzyl ethers by treatment with silver(II) oxide in methanol or isopropanol.

The reaction of dibenzalcyclohexanone with hydroxylamine hydrochloride afforded three compounds 1–3 including the aziridine 3 showing a 3′,3a′-trans configuration. Now we report on the isolation of a new aziridine 4, possessing a 3′,3a′-cis configuration. Its structure was deduced by 2D nmr and single crystal X-ray diffraction studies.

Substituted bromomethyl- and chloromethylbenzenes and bis(bromomethyl) benzenes were directly converted, in high yields, to the corresponding methyl- and isopropyl- benzyl ethers by treatment with silver(II) oxide in methanol or isopropanol.

The reaction of dibenzalacetones substituted on the aromatic ring with hydroxylamine hydrochloride and potassium hydroxide in refluxing ethanol affords several compounds. Herein, we report the structures and spectral properties of several oximes of 2-(4,5-dihydro-5-aryl-3-isoxazolyl)-1-arylethanones 6. Unusual behaviour on its 1 H-nmr and mass spectra was observed. Single crystal X-ray diffraction was performed on compound 6d to support our structural considerations about the title compounds

C 19 H 20 F 4 O 4 cristallise dans P2 1 avec a=9.912, b=8.415, c=11.096A, β=99.98°, Z=2; affinement jusqu'a R=0.064. C 20 H 20 F 6 O 4 cristallise dans P2 1 avec a=10.348, b=8.388, c=11.093A, β=97.64°, Z=2; affinement jusqu'a R=0.033. Les centres chiraux formes lors de la difluorocarbenation de la zaluzanine D on ete determines par rapport au centre chiral 7S trouve dans la zaluzanine et la plupart des guaianolides.

C 17 H 24 O 4 cristallise dans P2 1 avec a=7,883, b=14,347, c=27,673 A, β=96,73 o , Z=8; affinement jusqu'a R=0,050. La stereochimie pour les diastereomeres I et III et II et IV autour de C(1), C(4), C(8) et C(12) est respectivement (R, S, R, S) et (S, R, S, R). Les cycles a 6 chainons adoptent des conformations bateaux oblique (gauche) [molecules (I) et (III)] et demi-chaise [molecule (II) et (IV)]. Les cycles a 5 chainons adoptent des conformations enveloppe β [molecule (I)] demi-chaise [molecule (III)] et l'intermediaire entre enveloppe α et demi-chaise [molecules (II) et (IV)]. La structure du cristal est stabilisee par un reseau tridimensionnel de liaisons hydrogene et quatre interactions intermoleculaires C−H...O

The ene-ene [2+2] cycloaddition of 2-benzyl-5-benzylidenecyclopentanone proceeds smoothly and spontaneously in benzene-d6 or deuteriochloroform solution to give two different diphenyl dispiro [4.1.4.1] dodecan-4,11-diones. Detailed 1H and 13C 2DNMR spectroscopy (COSY, HMQC, HMBC) were performed in order to prove the existence in solution of two cyclobutane derivatives, one a previously described photodimer obtained by the UV irradiation of crystals of 2-benzyl-5-benzylidenecyclopentanone.

C 17 H 16 F 4 O 3 cristallise dans C2 avec a=19.271, b=6.430, c=12.456A, β=91.70°, Z=4; affinement jusqu'a R=0.046. L'analyse par rayons X permet de corriger la configuration du difluorocyclopropane rattache aux carbones C1 et C10. La configuration est 1S,5R,10S,11S par rapport au centre 7S

(1987). SIMPLE PHASE-TRANSFER ALKYLATION OF O-(TETRAHYDROPYRAN-2-YL) ARYLALDEHYDE CYANOHYDRINS. Organic Preparations and Procedures International: Vol. 19, No. 6, pp. 427-432.

The reaction of dibenzalcyclohexanone with hydroxylamine hydrochloride affords three compounds: the oxime of 2-benzylidenecyclohexanone (2), 3-phenyl-7-benzylidene-3,3a,4,5,6,7-hexahydro-2,1-benzisoxazole (3) and 3-phenyl-3,3a,4,5,6,7-hexahydro-2,1-benzisoxazole-7-spiro-2′-(3′-phenylaziridine) (4). Their structures were deduced by 2D NMR analysis. Single-crystal x-ray diffraction was used to confirm the structure and stereochemistry of 4. A possible mechanism for this reaction is proposed.

A simple and efficient method to prepare alkyl 3,5-dioxohexanoates by alcoholysis of isopropylidene (1-hydroxy-3-oxo-butylidene) malonate is described.

C 10 H 10 O 4 cristallise dans P2 1/c avec affinement jusqu'a 0,046. Les jonctions A/B et B/C sont cis. L'empilement des molecules dans le cristal est du aux contacts intermoleculaires C−H… O et forces de Van der Waals

C 10 H 10 O 4 cristallise dans P2 1/c avec affinement jusqu'a 0,046. Les jonctions A/B et B/C sont cis. L'empilement des molecules dans le cristal est du aux contacts intermoleculaires C−H… O et forces de Van der Waals

A simple and efficient method to prepare alkyl 3,5-dioxohexanoates by alcoholysis of isopropylidene (1-hydroxy-3-oxo-butylidene) malonate is described.

(1987). SIMPLE PHASE-TRANSFER ALKYLATION OF O-(TETRAHYDROPYRAN-2-YL) ARYLALDEHYDE CYANOHYDRINS. Organic Preparations and Procedures International: Vol. 19, No. 6, pp. 427-432.

The synthesis of praziquantel (1), a potent anthelmintic agent, is reported. The synthesis requires five steps and proceeds in 16% yield.