Enzymatic Synthesis of [3-14C]Cinnamic Acid

Convenient and efficient route of the synthesis of [3-¹⁴C] cinnamic acid is reported. [1-¹⁴C]Benzoic acid, prepared by carbonation of Grignard reagent with [¹⁴C]carbon dioxide, was reduced to [1-¹⁴C]benzyl alcohol. In the enzymatic step this alcohol was selectively oxidised to [1-¹⁴C]benzaldehyde using enzyme YADH (Ec. 1.1.1.1) and immediately condensed with malonic acid. This combined chemical and enzymatic approach allows to obtain [3-¹⁴C]cinnamic acid with radiochemical yield higher than 50% in respect to the starting alcohol.     

Remote controlled unit for the production of [2-11C] isopropyl iodide

A remote controlled system is described for the production of [2-¹¹C] isopropyl iodide. The synthesis involves carbonation of methyl lithium with¹¹CO₂ followed by reduction with lithium aluminum hydride, hydrolysis and iodination with hydroiodic acid. The purification is performed by preparative gaschromatography on a Chromosorb 102-Porapak Q column. For a 30 min irradiation at 15 A beam intensity the method yields about 300 mCi /11 GBq/ of radiochemically and chemically pure [2-¹¹C] isopropyl iodide with a specific activity of 210 to 250 mCi. mol^–1 at the end of synthesis /EOB+25 min/. The remote controlled unit is also useful for the production of other alkyl iodides, acetone and acetic acid, labelled with¹¹C.     

Biosynthesis of cytochalasans. Part 4. The mode of incorporation of common naturally-occurring carboxylic acids into cytochalasin D1.

Utilization of sodium [1-¹⁴C]-, [2–¹⁴C]-, and [1,2-¹³C]-acetates, [1-¹⁴C]-, [1-¹³C]-, or [2-¹⁴C]-propionates, [1-¹⁴C]-or [2-¹⁴C]-malonates, of [1-¹⁴C]- or of [1-¹⁴C]-myristic acid, or of [1-¹⁴C]- and [1-¹⁴C]-palmitic acid in the biosynthesis of cytochalasin D ( 1 ) by Zygosporium masonii was determined by degradation studies or by carbon magnetic resonance spectroscopy. The precursors were incorporated primarily via the acetate-malonate pathway to generate 1 from nine intact acetate units, eight of which are coupled in a head to tail fashion to form the C₁₆-polyketide moiety.     

Synthesis of [1-14C]-labeled mandelic acid under microwave condition

Summary We report here a facile synthesis of [1-¹⁴C]-mandelic acid. Benzyl bromide on cyanation with K¹⁴CN followed by acid hydrolysis in a microwave oven gave [1-¹⁴C] phenylacetic acid. The latter on a-bromination followed by hydrolysis under microwave irradiation for 2 minutes furnished the title compound.     

Zum Mechanismus der α-Alkinon-Cyclisierung: Synthese und Thermolyse von 1-(1-Methylcyclopentyl)[3-13C]prop-2-inon

On the Mechanism of the α-Alkynone Cyclization: Synthesis and Thermolysis of 1-(1-Methylcyclopentyl)[3-¹³C]prop-2-ynone The relative migratory aptitude of two acetylenic substituents in the α-alkynone cyclization, a thermal conversion of α-acetylenic ketones A to 2-cyclopentenones C , was investigated by isotope-labeling experiments. The α-alkynone [β-¹³C]- 1 , specifically labeled with ¹³C at the β-acetylenic C-atom C(3), was synthesized by an intramolecular Witting reaction (230–300°) of the diacylmethylidenephosphorane [¹³C]- 7. The latter resulted from acylation of methylidenetriphenylphosphorane with the acid chloride 4 to yield the acylmethylidenephosphorane 5 , which in turn was formylated with acetic [¹³C]formic anhydride ([¹³C]- 6. ) Upon thermolysis of [β-¹³C]- 1 , its label at C(β) was transferred almost exclusively to C(β) of the 2-cyclopentenone moiety in the resulting cyclization product [¹³C]- 2. We conclude that there is a distinct preference for hydrogen migration in the acetylene → alkylidene carbene isomerization (A → B) which precedes the cyclization step (B → C). No evidence was found for a fast reversibility of this isomerization (A ? B) involving both acetylenic substituents.     

An improved radiometric assay of plant peroxidases based in the decarboxylation of indole-3-[1-14C]acetic acid

A radiometric microassay has been developed to measure the indole-3-acetic acid oxidizing activity of plant peroxidases. This was based in a reappraisal of the pre-existing assay of the indole-3-acetic acid oxidase activity based in the decarboxylation of indole-3-[1-¹⁴C]acetic acid. The improvement consists in the measurement of the indole-3-acetic acid decarboxylation by the determination of the decrease of radioactivity due to the decarboxylation of indole-3-[1-¹⁴C]acetic acid carried out in open vessels, during the steady-state (peroxidative) phase of the oxidation rate. In contrast to the previously reported radiometric methods, the reliability (kinetic stoichiometry of the decarboxylation) of our microassay was studied, and it was supported by the fact that, for steady-state conditions, a kinetic correlation between the disappearance of labelled substrate and the appearance of the first decarboxylate product takes place. The sensitivity and reproducibility of the improved assay was tested with crude protein samples taken from cellular homogenates of lupin hypocotyls.     

Synthesis of 1-phenyi-1H-tetrazolo[4,5-d]tetrazole and 5-aryl-1-(4-bromophenyl)-1,2,4-triazolo[4,3-d]tetrazoles

l-Phenyl-lH-tetrazol-5-yIhydrazine (2) was reacted with nitrous acid to yield 1-phenyl-lH-tetrazolo[4,5-d]tetrazole (3). l-Arylidene-2-(l-phenyl-lH-tetrazol-5-yl)hydrazines (4) were generally reactive towards electrophilic reagents. When treated with bromine in acetic acid, 4 yielded mixtures of 1-arylidene-2-[1-(4-bromophenyl)-lH-tetrazol-5-yl]hydrazines (5a-d) and 2-[1-(4-bromophenyl)-lH-tetrazol-5-yl]hydrazidic bromides (6a-d). Solvolysis of 6a-d in aqueous acetone yielded 5-aryl-1-(4-bromophenyl)-1,2,4-triazolo[4,3-d]tetrazoles (7a-d). The structures of the synthesized compounds were confirmed on the basis of elemental analysis, IR and ¹H NMR data.     

Facile conversion of [1-<Superscript>14</Superscript>C]lauronitrile to [1-<Superscript>14</Superscript>C]lauric acid under microwave irradiation

Summary A highly efficient and an optimized synthesis of [1-¹⁴C]lauric acid with high specific activity (50 mCi/mmol) is described. [1-¹⁴C]lauric acid was prepared from [1-¹⁴C]lauronitrile, in 2 minutes with a mixture of concentrated hydrochloric acid: propionic acid (1: 2 v/v) under microwave irradiation, in quantitative yield.     

Synthesis of dl-[2-13C]leucine and it use in the preparation of [3-dl-[2-13C]leucine]oxytocin and [8-dl-[2-13C]leucine]oxytocin: Preparative separation of diastereoisomeric peptides by partition chromatography and high pressure liquid chromatography

dl-[2-¹³C]Leucine was prepared by condensing the sodium salt of ethyl acetamido-[2-¹³C]cyanoacetate with isobutylbromide in hexamethylphosphoroustriamide followed by acid hydrolysis. N-Boc-dl-[2-¹³C]Leucine was prepared and incorporated into [8-dl-[2-¹³C]leucine]oxytocin by total synthesis. The ¹³C-labeled hormone derivative [8-[2-¹³C]leucine]oxytocin was separated from its 8-position diastereoisomer by partition chromatography. The specifically ¹³C-labeled peptide hormone diastereoisomeric analog [3-dl-[2-¹³C]leucine]oxytocin also was prepared by solid phase peptide synthesis. No suitable solvent system for partition chromatography separation of the latter diastereoisomeric peptide mixture could be found. However an excellent preparative separation of the diastereoisomers could be obtained by reverse phase high pressure liquid chromatography on a partisil 10 M9 ODS column using the solvent system 0.05 M ammonium acetate (pH 4.0), acetonitrile (81:19, $\text{v}\text{v}$) to give pure [3-(2-¹³C]leucine]oxytocin and [3-D-(2-¹³C]leucine]oxytocin. An excellent separation of [8[2-¹³C]leucine]oxytocin and the corresponding 8-D-leucine diastereoisomer derivative could also be accomplished by high pressure liquid chromatography.     

Biosynthese de la botryodiplodine,mycotoxine de penicillium roqueforti: Incorporations d'acetate[1-13C], [2-13C], [1-2 13C]et d'acide orsellinique 2-13C-carboxyle 13C], [3-4 13C]

Incorporations of [1-¹³C], [2-¹³C], [1-2¹³C]acetate and [2-¹³C, carboxyl-¹³C], [3-4¹³C]orsellinic acid into botryodiplodin indicate that this mycotoxin is biosynthesized by the polyketide pathway. Orsellinic acid is a precursor of botryodiplodin. A biosynthetic pathway, using orsellinic acid as precursor, is proposed.     

Synthesis of 24-Methylidene[24-14C]- and 24-Methylidene[7-3H]cholesterol

The syntheses of 24-methylidene[24-¹⁴C]cholesterol ( 7a ) and of 24-methylidene[7-³H]cholesterol ( 7b ) from commercially available (20S)-3-oxopregn-4-ene-20-carbaldehyde ( 1 ) are described. The method also provides simple preparations of 3β-acetoxy[24-¹⁴C]chol-5-en-24-oic acid ( 4 ) and 24-oxocholest-5-en-3β-yl acetate ( 6b ).     

Biosynthesis of verrucarins and roridins. 2. Incorporation of acetate in cis-transmuconic acid and of mevalonate in roridinic acid]

Incorporation experiments using sodium [1-¹⁴C]-acetate and sodium [2-¹⁴C]- and [2-¹⁴C,2-³H₂]-mevalonate and degradations of the verrucarin A ( 1 ) and roridin A ( 2 ) so produced demonstrate that cis,trans-muconic acid ( 3 ) is formed from 3 acetate units. The cis,trans-muconic acid and the C₂-side-chain structural elements of roridinic acid ( 6 ) are built up from 4 acetate units; the cis-oricntcd C(11)-carboxyl group of 6 originates from C(1) of acctic acid. The structural moiety of roridinic acid ( 6 ) corresponding to verrucarinic, acid ( 7 ) originates from mevalonate, as does 7 . A new degradation scheme was devised for roridinic acid ( 6 ); the oxime 23 of its 13 dehydro-detrahydro derivative 21 underwent cleavage with SOCl₂ and subsequent hydrolysis to yield verrucarinolactone ( 8 ), acetonitrile ( 26 ) and methyl adipaldohydate ( 27 ) by a heterolytic Beckmann fragmentation reaction.     

Synthesis of 1′-aryl-2′-(2-oxoindolin-3-yl)spiro[indoline-3,5′-pyrroline]-2,3′-dione via one-pot reaction of arylamines, acetone, and isatins

An efficient synthetic method for 1′-aryl-2′-(2-oxoindolin-3-yl)spiro[indoline-3,5′-pyrroline]-2,3′-diones was successfully developed via the one-pot domino reaction of arylamines, acetone, and isatins in acetic acid. The reaction mechanism involved the sequential Michael addition and ring closure of the in situ formed 3-N-aryliminoisatin and isatylidene acetone.     

Biosynthesis of the Verrucarins and Roridins. Part 1. The transformation of mevalonic acid into verrucarinic acid. Evidence for a hydrogen 1,2-shift. Verrucarins and roridins, 27th communication

Incorporation experiments using sodium [2-¹⁴C]-, [2-³H]-, (3R)-[5-¹⁴C]- and [2-³H, 2-¹⁴C]-mevalonates and with mevalonates stereospecifically tritiated at C(2) demonstrate the transformation of mevalonic acid ( 8 ) into verrucarinic acid ( 5 ). Degradation experiments showed that this transformation occurs with a hydrogen 1, 2-shift of the ‘pro-2R’ hydrogen atom of mevalonate to C(3) of verrucarinate. A possible mechanistic pathway is discussed.     

Ring closure of 1-[4-(imidazol-1-yl)phenyl]-3-phenyl-2-propen-1-one derivatives to potential biologically active compounds

1-[4-(Imidazol-1-yl)phenyl]-3-phenyl-2-propen-1-one 1 reacted with acetone cyanohydrin, ethyl phenylacetate and cyanoacetamide to give the adducts 2, 8 and 10 respectively. Action of hydrazine hydrate on both the γ-ketonitrile 2 and the corresponding γ-ketoacid 4 led to pyridazine derivatives 3 and 5 . 4,5-Dihydropyridazinone 5 was dehydrogenated by the action of bromine in acetic acid to give pyridazinone 6 . Cyclization of acid 8 in acetic medium resulted in α-pyrone 9 . Cyanopentanamide 10 was converted with hydrochloric acid into δ-ketoacid 13 which led to α-pyrone 14 via an intramolecular dehydration. Refluxing 10 in the presence of acetic acid and ammonium acetate gave 3,4-dihydropyridone 11 which was dehydrogenated to produce pyridone 12 .     

An Efficient Synthesis of Optically Active [4-13C] Labelled Quorum Sensing Signal Autoinducer-2

A new synthetic route for the quorum sensing signal Autoinducer-2 (AI-2) is described and used for the preparation of [4-¹³C]-AI-2 starting from [1-¹³C]-bromoacetic acid. The key step in this process was the enantioselective reduction of an intermediate ketone. This synthesis provides, selectively, both enantiomers of the labelled or unlabelled parent compound, (R) or (S)-4,5-dihydroxypentane-2,3-dione (DPD) and was used for an improved synthesis of [1-¹³C]-AI-2.     

Synthesis,antimicrobial, and mitotic toxicity evaluation of new 6-substituted 2-(benzo[4,5]imidazo[1,2-c]quinazolin-5(6H)-yl)acetic acids

A series of novel 6-substituted 2-(benzo[4,5]imidazo[1,2-c]quinazolin-5(6H)-yl)acetic acids were synthesized and characterized by ¹H, ¹³C, ¹⁹F NMR, ¹H-¹H-COSY, ¹H-¹³C-HSQC, NOESY, LC-MS, IR, and elemental analysis. The mitotic toxicity of the synthesized compounds was determined according to the Allium test procedure. The 2-(6-(pentafluorophenyl)benzo[4,5]imidazo[1,2-c]quinazolin-5(6H)-yl)acetic acid inhibited mitotic spindle formation, which resulted in significant cytotoxic effect for meristematic cells of Allium cepa l . roots. In a preliminary antimicrobial evaluation, only Streptococcus pyogenes and Candida albicans were slightly susceptible to some of the synthesized compounds.     

A facile synthesis of 4,6-dimethoxy-[2-<Superscript>14</Superscript>C]-2-methylsulphonylpyrimidine

Summary 4,6-dimethoxy-2-methylsulphonylpyrimidine is a key intermediate for the synthesis of pyrithiobac-sodium, a selective herbicide for cotton plant. ¹⁴C labeled pyrithiobac-sodium is required for studying the translocation and metabolism in cotton plants. It was prepared by oxidation of 4,6-dimethoxy-[2-¹⁴C]-2-methylmercaptopyrimidine with H₅IO₆/CrO₃ in ethyl acetate at room temperature to give 4,6-dimethoxy-[2-¹⁴C]-2-methylsulphonylpyrimidine in high yields.     

Chemical behaviour of N-(2-hydroxybenzyl)anthranilic acids in the presence of acyclic anhydrides

The synthesis of 11-acyl-11,12-dihydrodibenz[bf][1,5]oxazocin-6-ones 9-13 is reported by reaction of N-(2-hydroxybenzyl)anthranilic acids 1 with acetic, isobutyric, 2-ethylbutyric anhydrides. The structures of the obtained 6,8,6 products are proved with the use of ir, mass spectrometry, ¹H and ¹³C nmr spectra, homo-and heteronuclear two-dimensional nmr experiments. The formation of 9-13 is discussed in relation to the obtainment of 12H-quino[2,1-b][1,3]benzoxazin-5-ones 2-8 and 6a,12-dihydro[3,1]benzoxazino[2,1-b][1,3]-benzoxazin-5-ones 14-19 from the same starting products 1 with suitable anhydrides under controlled reaction conditions.