A Total Synthesis of (±)-Gibberellin A12 via Methyl (±)-7,16-dioxo-17-norkauran-19-oate

¹⁴C-labelled methionine, xanthosine, and 7-methylxan-thosine were given to excised tea shoots. The methyl group of methionine was incorporated into 7-methylxanthosine (ca. 10%) in the earlier period of incubation after the uptake. About 50% of the radioactivity of xanthosine was rapidly incorporated into caffeine via 7-methylxanthosine, 7-methylxanthine, and theobromine within 24 hr. 7-Methylxanthosine was also converted into caffeine at a high rate. The results suggest that the pathway for caffeine biosynthesis is as follows: xanthosine → 7-methylxanthosine → 7-methylxanthine → theobromine → caffeine.     

Synthesis of Isochroman-1,3-diones A New Synthesis of (±)Sclerin

(±)Sclerin (4,5,6,7-tetramethyl-8-hydroxyisochroman-1,3-dione), a mycerial extracts of Sclerotinia libertiana, and related compounds were synthesized. Alkylated-7-hydroxyindanones were obtained from alkylated phenols and α-bromobutyrylbromide, and these indanone derivatives were treated with benzaldehyde to give 2-benzylidene-7-hydroxyindanone derivatives. By ozonolysis of these benzylidene-indanones were obtained 8-hydroxyisochroman-1,3-diones.     

Synthesis of (±)-licarin-B

The synthesis of (±)-licarin-B, a neolignan of Licaria aritu Ducke (Lauraceae), was achieved by pyrolysis of 3-hydroxy-3-piperonyl-1-propyl-2-methoxy-4-(E)-propenylphenyl ethers.     

Synthesis of (±)-Hydroxytremetone

(±)Hydroxytremetone (III) has been synthesized from 2-(α-hydoxyisopropyl)-6-hydroxycoumaran (V b) via its O-acetate V c by dehydration with phosphorus tribromide in pyridine solution, followed by acylation with a mixture of trifluoroacetic anhydride and acetic acid. Isohydroxytremetone (IX b) was also synthesized.     

Synthesis of (±)-Xanthoxins

The enzymatic properties of P2-2 enzyme were determined by using cells of M. radiodurans. The enzyme was: most active at 60°C incubation temperature, stable at 40°C in neutral buffer, and inactivated by heating at 80°C for 15min. Maximal lytic activity occurred at pH 8.5 in Tris-HCl buffer. The range of enzyme stability was between pH 5.5 and 8. Bivalent metal ions, p-chloromercuribenzoate and monoiodo acetate inhibited lytic activity. The molecular weight was estimated to be 16,000 daltons by gel filtration on Sephadex G-75. The enzymatic digestion of peptidoglycans from the cell walls of M. radiodurans and M. lysodeikticus liberated free amino groups, but neither reducing groups nor N-acetylhexosamine, indicating that the enzyme was an endopeptidase. From analysis of the N-terminal amino acids of the digests, it is suggested that the P2-2 enzyme cleaves the peptide bond at the carboxyl group of D-alanine in peptidoglycan.     

Synthesis of (±)-Homosarkomycin and (±)-Rosaprostol

(±)-Homosarkomycin (2) and (±)-rosaprostol (3) were synthesized from (±)-methyl 2-oxo-bicyclo[3.1.0]hexane-1-carboxylate (1) by using the nucleophilic ring opening reaction on the double-activated cyclopropane ring as the key step.     

Synthesis of (±)-Lamprolobine and (±)-Epilamprolobine

(±)-Lamprolobine, the (+)-enatiomer of which was isolated from the leaves of Lamprolobium fruticosum, and (±)-epilamprolobine were synthesized from δ-valerolactam.     

Synthesis of (±)-Tubaic Acid

An alternative synthesis of (±)-tubaic acid (I), a key intermediate compound of rotenone synthesis, has been accomplished by the Wittig reaction.     

Total Synthesis of (±)-Sermundone and An Alternative Cyclization Method to Dehydrorotenoids

(±)-Sermundone (2), one of the hydroxyrotenoids, has been synthesized. Also a new cyclization method to dehydrorotenoids has been developed using alkali metal salts.     

A Novel Synthesis of (±)-Munduserone via Acetylenic Intermediates

A riboflavin α-glucoside-synthesizing enzyme from the acetone powder of pig liver was purified by a procedure including fractionation with ammonium sulfate, heat treatment, fractionation with acetone, gel filtration on a Sephadex G-150 column, calcium phosphate gel treatment, and isoelectric focusing. A final enzyme preparation was homogeneous on polyacrylamide disc gel electrophoresis and in the ultracentrifuge. The enzyme had a sedimentation coefficient of 9.90 S and an isoelectric point of pH 3.7. The enzyme had a pH optimum at 6.0 with maltose as substrate. The enzyme catalyzed the hydrolysis of diverse kinds of α-glucosidic substrates, and the transfer of α-glucosyl residue from these substrates to riboflavin. The Km value for maltose was 1.20×10^?3m. The enzyme hydrolyzed phenyl α-maltoside to glucose and phenyl α-glucoside. Amylose was almost completely hydrolyzed to glucose by the enzyme. Maltotriose was obtained as the main transfer product after the treatment of maltose with the enzyme. The enzyme also catalyzed the transfer of α-glucosyl residue from maltose to pyridoxine, esculin, rutin, and adenosine. It was recognized that a single enzyme catalyzed not only the hydrolysis of maltose and α-glucosidic substrates but also the transfer of the α-glucosyl residue of these substrates to suitable acceptors.     

Biomimetic Total Synthesis of ( – )-Aplysistatin

A biomimetic synthesis of ( – )-aplysistatin (1) is described. The Wittig reaction of the keto ester 5 with homogeranyl triphenylphosphonium ylid gave the desired intermediate 3. Successive treatment of 3 with activated manganese dioxide, sodium chlorite and aq. trifluoroacetic acid led to the unsaturated β-hydroxy lactone 2, which was subjected to brominative cyclization to yield ( –)-aplysistatin (1).     

Synthesis of ( ± )-Methyl Epijasmonate and ( ± )-Methyl Cucurbate

A novel synthesis of ( ± )-methyl epijasomonate (2) and the first synthesis of ( ± )-methyl cucurbate (4) were achieved starting from 2-allylcyclohexane-1,3-dione (8). The synthetic epimer 2 had a stronger jasmin flavor than the trans-isomer 1 with 95% purity.     

Total synthesis of (±)-elegansidiol, (±)-farnesiferol B,and (±)-farnesiferol D

The racemic total synthesis of elegansidiol, farnesiferol B, and farnesiferol D has been obtained following a Diels–Alder approach. Gillman addition, cross metathesis reaction are the other key steps involved in the target synthesis.     

Synthesis of (±)-Epoxydon and Related Natural Compounds

Synthesis of (±)-phyllostine, (±)-epoxydon, (±)-epiepoxydon, (±)-epoformin and (±)-epiepoformin by the retro-Diels—Alder reaction was described.     

Synthesis and Biological Activities of (±)-Deoxy-abscisic Acid Isomers

Phosphodiesterase production with bis-p-nitrophenyl phosphate as a substrate by alkalophilic Bacillus No. A-40-2 increased with increasing Mn²⁺ concentration, showing maximum productivity at 10 mm. The enzyme production was negligible in the medium without Mn²⁺. The simultaneous addition of 10 mm Mn²⁺ and one of the several cations Mg²⁺, Co²⁺, Mo⁶⁺, and Pb²⁺ at suitable concentrations stimulated the enzyme production 1.8-fold at most over that with only 10 mm Mn²⁺. Inorganic phosphate hardly repressed the enzyme production. The enzyme was purified homogeneously. The purified enzyme had the optimum pH of 7.5 and was fairly stable from pH 7–11. The enzyme hydrolyzed 2′,3′-cyclic-nucleotides and 3′-nucleotides, but did not hydrolyze 3′,5′-cyclic-nucleotides or 5′-nucleotides, indicating it to be a 2′,3′-cyclic-nucleotide 2′-phosphodiesterase (EC 3.1.4.16). The enzyme had activity without metals, but Mg²⁺, Ca²⁺, Ba²⁺, and Mo⁶⁺ activated the enzyme reaction.     

A New Synthesis of (—)-exo-Brevicomin

Rubusoside derivatives by transgalactosylation of various β-galactosidases were isolated and their structures were analyzed. Escherichia coli β-galactosidase produced mainly 13-O-β-d-glucosyl-19-O-[β-d-galactosyl-(1→6)-β-d-glucosyl]-steviol (RGal-2). Bacillus circulans β-galactosidase produced mainly 13-O-β-d-glucosyl-19-O-[β-d-galactosyl-(1→4)-β-d-glucosyl]-steviol (RGal-1a) in the early stage of the reaction and then produced 13-O-[β-d-galactosyl-(1→4)-β-d-glucosyl]-19-O-β-d-glucosyl-steviol (RGal-1b). With decreasing the amount of these products (RGal-1a and RGal-1b), RGal-2 was produced.     

Synthesis of (±)-Sundiversifolide Based on Lewis Acid-Mediated Claisen Rearrangement

A new and concise synthesis of (±)-sundiversifolide (1), an allelopathic bisnor-sesquiterpene lactone isolated from germinating sunflower (Helianthus annuus L.) seeds, was achieved by employing Lewis acid-mediated Claisen rearrangement as the key step.     

Concise synthesis of (±)-litseaones A and B

A concise synthesis of litseaones A and B, which were isolated from the stem barks of Litsea rubescens and L. pedunculata, is described in this study. Litseaone A was synthesized in just three steps from a known phloroglucinol derivative. The direct conversion of litseaone A into litseaone B was also achieved.     

A Stereoselective Synthesis of (±)-endo-Brevicomin,a Pheromone Inhibitor Produced by Dendroctonus Bark Beetles

Prediction of elution curves in gel chromatography was attempted on the basis of a mass balance model which gave consideration to gel phase diffusion and longitudinal dispersion in a column. The basic differential equations for the model were solved by means of Laplace transformation, and then the solution in Laplace domain was inverted into time domain numerically. The calculated elution curves were in good agreement with the experimental ones of NaCl and myoglobin with various Sephadex gel columns. This indicated the validity of the calculation method and the model employed in this study.

Furthermore, the elution curves were calculated tentatively for various combinations of the parameters appearing in the mass balance model. Then, the magnitude of peak asymmetry, the shift of peak position and the maximum peak height of the elution curves were correlated with various parameters and operational variables. These correlations might permit prediction of suitable operational conditions for gel chromatography, especially for molecular weight determination.