Highly selective biotransformation of (+)-(1S)- and (−)-(1R)-camphorquinone by Aspergillus wentii

Abstract

To clarify the structures of biotransformation products and metabolic pathways, the biotransformation of monoterpenoids, (+)- and (?)-camphorquinone (1a and b), has been investigated using Aspergillus wentii as a biocatalyst. Compound 1a was converted to (?)-(2S)-exo-hydroxycamphor (2a), (?)-(2S)-endo-hydroxycamphor (3a), (?)-(3S)-exo-hydroxycamphor (4a), (?)-(3S)-endo-hydroxycamphor (5a), and (+)-camphoric acid (6a). Compound 1b was converted to (+)-(2R)-exo-hydroxycamphor (2b), (+)-(2R)-endo-hydroxycamphor (3b), (+)-(3R)-exo-hydroxycamphor (4b), (+)-(3R)-endo-hydroxycamphor (5b), and (?)-camphoric acid (6b). Compound 1a mainly produced 2a (65.0%) with stereoselectivity, whereas 1b afforded 3b (84.3%) with high stereoselectivity. These structures were confirmed by gas chromatography–mass spectrometry, infrared, ¹H nuclear magnetic resonance (NMR), and ¹³C NMR spectral data. The products illustrate the marked ability of A. wentii for enzymatic oxidation and ketone reduction.     

Enantiotopically Selective Oxidation of 1,5-Diols with Gluconobacters Preparation of (S)-Mevalonolactone

(±)-(2Z,4E)-α-Ionylideneacetic acid (2) was enantioselectively oxidized to (?)-(l′S)-(2Z,4E)-4′-hydroxy-α-ionylideneacetic acid (3), (+)-(1′R)-(2Z,4E)-4′-oxo-α-ionylideneacetic acid (4) and (+)-abscisic acid (ABA) (1) by Cercospora cruenta IFO 6164, which can produce (+)-ABA and (+)-4′-oxo-α-acid 4. This metabolism was confirmed by the incorporation of radioactivity from (±)-(2-¹⁴C)-(2Z,4E)-α-acid 2 into three metabolites. (?)-4′-Hydroxy-α-acid 3 was a diastereoisomeric mixture consisting of major 1′,4′-trance-4′-hydroxy-α-acid 3a and minor 1′,4′-cis-4′-hydroxy-α-acid 3b. These structures, 3a and 3b, were confirmed by ¹³C-NMR and ¹H-NMR analysis. Also, the enantioselectivity of the microbial oxidation was reexamined by using optically pure α-acid (+)-2 and (?)-2, as the substrates.     

Regioselective acylation of several polyhydroxylated natural compounds by Candida antarctica lipase B

Regioselective acylation of four polyhydroxylated natural compounds, deacetyl asperulosidic acid (1), asperulosidic acid (2), puerarin (3) and resveratrol (4) by Candida antarctica Lipase B in the presence of various acyl donors (vinyl acetate, vinyl decanoate or vinyl cinnamoate) was studied. Compounds 1, 2 and 4 were regioselectively acetylated with vinyl acetate to afford products, 3′-O-acetyl-10-O-deacetylasperulosidic acid (1a), 3′,6′-O-diacetyl-10-O-deacetylasperulosidic acid (1b), 3′-O-acetylasperulosidic acid (2a), 3′,6′-O-diacetylasperulosidic acid (2b), 4′-O-acetylresveratrol (4a), respectively, with yields of 22 to 50%, while reactions with vinyl decanoate and vinyl cinnamoate were slow with lower yields. Compound 3 was readily acylated with all three acyl donors and quantitatively converted to products 6″-O-acetylpuerarin (3a), 6″-O-decanoylpuerarin (3b), 6″-O-cinnamoylpuerarin (3c), respectively. The structures of these acylated products were determined by spectroscopic methods (MS and NMR).     

Synthesis and Antimicrobial Activity of Chiral cis-Cycloheximide Isomers

Such (+)- and (?)-cis-cycloheximide isomers as isocyclohcximide (1a, 1b), α-epiisocycloheximide (2a, 2b) and neocycloheximide (3a, 3b) were synthesized by aldol condensation of (?)-(2R, 4R)- and (+)-(2S, 4S)-cis-2,4-dimethyl-1-cyclohexanone (5a, 5b). obtained by microbial resolution, with 4-(2-oxoethyl)-2,6-piperidinedione (7). The absolute configuration of the (?)-cis-ketone 5a was confirmed by chemical correlation with natural (2S, 4S, 6S, αR)-cycloheximide (4). The newly synthesized isomer, (?)-α-epiisocycloheximide (2b), showed strong antimicrobial activity against S. cerevisiae andP. oryzae close to that of natural cycloheximide (4).     

Definitive Solution Structures for the 6-Formylated Versions of 1-(βD-Ribofuranosyl)-, 1-(2′-Deoxy-β-D-Ribofuranosyl)-, and 1-β-D-Arabinofuranosyluracil,and of Thymidine

Abstract

ROESY and NOESY NMR spectroscopic analyses of the ribofuranosyl (1a), 2′-deoxyribofuranosyl (1b), and arabinofuranosyl (1c) derivatives of 6-formyluracil in (CD₃)₂SO and D₂O solutions have established that each exclusive 7,05′-cyclic hemiacetal diastereomer of 1a,b and the major 7,O2′-cyclic hemiacetal diastereomer of 1c possess the 7R configuration. In addition, (7R)-1c has been shown to be thermodynamically more stable than (7S)-1c, contrary to our previous indication. A new, higher yielding synthetic route to 1a has been developed, 1b has been obtained for the first time in crystalline form, the route to 1c has been modified to better accommodate large scale preparations, and a new, fourth member of this class, 6-formylthymidine (1d), has been synthesized and its solution structures in (CD₃)₂SO, D₂O, and CD₃OD have been determined. Antitumor and antiviral evaluations of 1a-c have revealed no significant levels of activity.     

Synthesis of 2-Bromomethyl-3-Hydroxy-2-Hydroxymethyl-Propyl Pyrimidine and Theophylline Nucleosides Under Microwave Irradiation. Evaluation of Their Activity Against Hepatitis B Virus

Alkylation of 2-methylthiopyrimidin-4(1H)-one (1a) and its 5(6)-alkyl derivatives 1b–d as well as theophylline (7) with 2,2-bis(bromomethyl)-1,3-diacetoxypropane (2) under microwave irradia-tion gave the corresponding acyclonucleosides 1-[(3-acetoxy-2-acetoxymethyl-2-bromomethyl)prop-1-yl]-2-methyl-thio pyrmidin-4(1H)-ones 3a–d and 7-[(3-acetoxy-2-acetoxymethyl-2-bromomethyl)prop-1-yl]theophylline (8), which upon further irradiation gave the double-headed acyclonucleosides 1,1 ′-[(2,2-diacetoxymethyl)-1,3-propylidene]-bis[(2-(methylthio)-pyrimidin-4(1H)-ones] 4a–c, and 7,7 ′-[(2,2-diacetoxymethyl)-1,3-propylidene]-bis(theophylline) (9). The deacetylated derivatives were obtained by the action of sodium methoxide. The activity of deacetylated nucleosides against Hepatitis B virus was evaluated. Compound 5b showed moderate inhibition activity against HBV with mild cytotoxicity.     

Synthesis of Certain Acyclic Nucleoside Analogs of 1,2,4-Triazolo[3,4-f][1,2,4]triazine and Pyrimido[5,4-d]pyrimidine

Abstract

Synthesis of 2-penten-1-yl (8a) and ganciclovir analog (8b) of 1,2,4-triazolo[3,4-f][1,2,4]triazine was accomplished by the ring annulation of the corresponding hydrazides (6a and 6b), which in turn was obtained by the dehydrative coupling of 4 with 5a or 5b. Base catalysed ring expansion of N9-alkylpurine-6-carbonitriles (10a 10c 10e) provided the acyclic analogs of 4-aminopyrimido-[5,4-d]pyrimidines (13a 13d 13e). Debenzylation of 13e afforded the ganciclovir analog (13f) of 4-amino-8-(β-D-ribofuranosylamino)-pyrimido[5,4-d]pyrimidine. However, compound 10b did not undergo the expected rearrangement but resulted in the formation of the methyl formimidate derivative (12).     

Preparation of Aroma Compounds by Microbial Transformation of Isophorone with Aspergillus niger

( ± )-cis-γ-Irone (1a), ( ± )-cis-dihydro-γ-irone (2a) and their trans- isomers (1b, 2b) were synthesized via 3,3-(Claisen) or 2,3-sigmatropic rearrangement of 1-hydroxymethyl-3,3,4- trimethyl-1-cyclo he xene (8) derivatives as each key step.     

柯拉斯那沉香的生物活性成分研究

为了解柯拉斯那(Aquilaria crassna)的化学成分,从其所产沉香中分离得到10个化合物,经波谱分析分别鉴定为:6,8-羟基-2-(2-苯乙基)色酮(1),6,8-二羟基-2-[2-(4-甲氧基苯)乙基]色酮(2),rel-(1a R,2R,3R,7b S)-1a,2,3,7b-tetrahydro-2,3-dihydroxy-5-(2-phenylethyl)-7H-oxireno[f][1]benzopyran-7-one(3),rel-(1a R,2R,3R,7b S)-1a,2,3,7b-tetrahydro-2,3-dihydroxy-[2-(4-methoxyphenyl)-ethyl]-7H-oxireno[f][1]benzopyran-7-one(4),rel-(1a R,2R,3R,7b S)-1a,2,3,7b-tetrahydro-2,3-dihydroxy-5-[2-(3-hydroxy-4-methoxyphenyl)-ethyl]-7H-oxireno[f][1]benzopyran-7-one(5),oxidoagarochromone B(6),oxidoagarochromone C(7),(5S,6R,7S,8R)-2-[2-(3′-hydroxy-4′-methoxyphenyl)ethyl]-5,6,7,8-tetrahydroxy-5,6,7,8-tetrahydrochromone(8),6,7-cis-dihydroxy-2-(2-phenylethyl)-5,6,7,8-tetrahydrochromone(9),N-trans-feruloyltyramine(10)。化合物3~5和8~10为首次从柯拉斯那沉香中分离得到。化合物1,3,6,7,9和10对乙酰胆碱酯酶具有一定的抑制活性,化合物4对人慢性髓原白血病细胞株K-562和人胃癌细胞株SGC-7901均具有较小的抑制作用,化合物1和3对人肝癌细胞株BEL-7402也有抑制活性。     

Synthesis and Biological Evaluation of 9-(f-2, c-3-Bishydroxymethyl-r-cyclopropylmethyl)-9H-adenine (A Lower Methylene Homolog of Carbocyclic Oxetanocin) and Related Compounds

Abstract

Adenine (7 and 16), thymine (9a and 18a), and 5-fluorouracil (9b and 18b) involving f-2, c-3-bishydroxymethyl-r-1-cyclopropylmethyl- and t-2 t-3-bishydroxymethyl-r-1-cyclopropylmethyl residues were synthesized, starting from trans-1, 4-dibenzyloxy-2-butene and its cis isomer, respectively. These compounds were evaluated for anti HSV-1 activity.     

Studies on the Chemical Synthesis of Potential Antimetabolites. 32.1 Synthesis of β-D-Pentofuranosyldeazaadenines as Candidate Inhibitors for S-Adenosylhomocysteinases and Methyltransferases

Abstract

9-β-D-Arabinofuranosyldeazaadenines [1-deaza-araA (4a) and 3-deaza-araA (4b)] were prepared from 6-chloro-β-D-ribofuranosyl-1- (6a) and -3-deazapurine (6b), respectively. Synthesis of 2′-deoxy-1-deaza-adenosine (5a) from 1-deazaadenosine (6c) is also described.     

Total Synthesis of ( + )-Methyl Phaseates

( ± )-Methyl phaseates were synthesized from ( ± )-4-(6′-acetoxymethyl-2 ′,6′-dimethyl-1′-cyclohexen-1′-y1)-but-3-en-2-one (20), which was prepared from a useful terpenoid building block, ( ± )-2-hydroxymethyl-2,6-dimethyl-1-cyclohexanone (11a and 11b). Photooxidation of the cyclohexadiene intermediate (22), followed by alkaline hydrolysis and methylation, gave four stereoisomers of ( ± )-methyl phaseates: (2Z,4E)-cis form (2), (2E,4E)-cis form (24), (2Z,4E)-trans form (25) and (2E,4E)-trans form (26).     

Fluorescent cytokinins: Stretched-out analogs of N6-benzyladenine and N6-(Δ2-isopentenyl) adenine

We have synthesized and compared the cytokinin activities in the tobacco bioassay of a series of benzologs of 6-(3-methyl-2-butenylamino)purine (N⁶-(Δ²-isopentenyl)adenine) (1a) and 6-benzylaminopurine (N⁶-benzyl-adenine) (1c). The linear benzo analogs 8-(3-methyl-2-butenylamino)imidazo[4,5-g]quinazoline (2b) and 8-benzyla-minoimidazo[4,5-g]quinazoline (2c) are active, while 9-(3-methyl-2-butenylamino)imidazo[4,5-f]quinazoline (3b) and 6-(3-methyl-2-butenylamino)imidazo[4,5-h]quinazoline (4b) are slightly active and 9-benzylaminoimidazo[4,5-f]-quinazoline (3c) and 6-benzylaminoimidazo[4,5-h]quinazoline (4c) are inactive. Compounds 2b and 2c represent the first examples of active cytokinins containing a tri-heterocyclic moiety. The above series of compounds demonstrates structural factors that affect cytokinin activity. These compounds also have interesting fluorescence properties which could render them useful as probes to study the mechanism of cytokinin action.     

Synthesis of Methylene-Bridged Analogues of Nicotinamide Riboside,Nicotinamide Mononucleotide and Nicotinamide Adenine Dinucleotide

Abstract

5-O-tert-Butyldimethylsilyl-1,2-O-isopropylidene-3(R)-(nicotinamid-2-ylmethyl)-α-D-ribofuranose (11a) and ?3(R)-(nicotinamid-6-ylmethyl)-α-D-ribofuranose (11b) were prepared by condensation of 5-O-tert-butyldimethylsilyl-1,2-O-isopropylidene-α-D-erythro-3-pentulofuranose (10) with lithiated (LDA) 2-methylnicotinamide and 6-methylnicotinamide, respectively, and then deprotected to give 1,2-O-isopropylidene-3-(R)-(nicotinamid-2-ylmethyl)-α-D-ribofuranose(12a) and 1,2-O-isopropylidene-3(R)-(nicotinamid-6-ylmethyl)-α-D-ribofuranose (12b). Benzoylation as well as phosphorylation of compounds 12 afforded the corresponding 5-O-benzoate (13b) and 5-O-monophosphates (14a and 14b). Treatment of 13b with CF₃COOH/H₂O caused 1,2-de-O-isopropylidenation with simultaneous cyclization to the corresponding methylene-bridged cyclic nucleoside - 3′,6-methylene-1-(5-O-benzoyl-β-D-ribofuranose)-3-carboxamidopyridinium trifluoro-acetate (8b) - restricted to the “anti” conformation. In a similar manner compounds 14a and 14b were converted into conformationally restricted 2,3′-methylene-1-(β-D-ribofuranose)-3-carboxamidopyridinium-5′-monophosphate (9a - “syn”) and 3′,6-methylene-1-(β-D-ribofuranose)-3-carboxamido -pyridinium-5′monophosphate (9b - “anti”) respectively. Coupling of derivatives 12a and 12b with the adenosine 5′-methylenediphosphonate (16) afforded the corresponding dinucleotides 17. Upon acidic 1,2-de-O-isopropylidenation of 17b, the conformationally restricted P¹-[6,3′-methylene-1-(β-D-ribofuranos-5-yl)-3-carboxamidopyridinium]-P²-(adenosin-5′-yl)methylenediphosphonate 18b -“anti” was formed. Compound 18b was found to be unstable. Upon addition of water 18b was converted into the anomeric mixture of acyclic dinucleotides, i. e. P¹-[3(R)-nicotinamid-6-ylmethyl-D-ribofuranos-5-yl]-P²-(adenosin-5′-yl)-methylenediphosphonate (19b). In a similar manner, treatment of 17a with CF₃COOH/H₂O and HPLC purification afforded the corresponding dinucleotide 19a.

     

Synthesis of Annonaceous Acetogenins from Muricatacin

Synthetic studies of annonaceous acetogenins starting from (?)-muricatacin (1a) or (+)-muricatacin are described, involving (?)-muricatacin (1a), mono-THF acetogenin, solamin (2), reticulatacin (3), (15R, 16R, 19S, 20S)-cis-solamin (4a) and (15S, 16S, 19R, 20R)-cis-solamin (4b), non-adjacent bis-THF acetogenin, 4-deoxygigantecin (5), and epoxide-bearing acetogenin, (15S, 16R, 19S, 20R)-diepomuricanin (6a).     

Diheteroarylmethyl substituted titanocenes: A novel class of possible anti-cancer drugs

From the reaction of tert-butyl lithium or n-butyl lithium with N-methylpyrrole (1a), furan (1b) or 2-bromo-thiophen (1c), 2-N-methylpyrrolyl lithium (2a), 2-furyl lithium (2b) or 2-thiophenyl lithium (2c), respectively, was obtained. When reacted with 6-(2-N-methylpyrrolyl) fulvene (3a), 6-(2-furyl) fulvene (3b) or 6-(2-thiophenyl) fulvene (3c), the corresponding lithiated intermediates were formed (4a-c). Titanocenes (5a-c) were obtained through transmetallation with titanium tetrachloride. When these titanocenes were tested against pig kidney epithelial (LLC-PK) cells, inhibitory concentrations (IC₅₀) of 32 μM, 140 μM, and 240 μM, respectively, were observed. These values represent improved cytotoxicity against LLC-PK, compared to their ansa-analogues.     

Synthesis of new pyridothienopyrimidinone derivatives as Pim-1 inhibitors

Four series of pyridothienopyrimidin-4-one derivatives were designed and prepared to improve the pim-1 inhibitory activity of the previously reported thieno[2,3-b]pyridines. Significant improvement in the pim-1 inhibition and cytotoxic activity was achieved using structure rigidification strategy via ring closure. Six compounds (6c, 7a, 7c, 7d, 8b and 9) showed highly potent pim-1 inhibitory activity with IC₅₀ of 4.62, 1.18, 1.38, 1.97, 8.83 and 4.18?μM, respectively. Four other compounds (6b, 6d, 7b and 8a) showed moderate pim-1 inhibition. The most active compounds were tested for their cytotoxic activity on three cell lines [MCF7, HCT116 and PC3]. Compounds 7a [the 2-(2-chlorophenyl)-2,3-dihydro derivative] and 7d [the 2-(2-(trifluoromethyl)-phenyl)-2,3-dihydro derivative] displayed the most potent cytotoxic effect on the three cell lines tested consistent with their highest estimated pim-1 IC₅₀ values.     

Novel benzyl-substituted molybdocene anticancer drugs

From the reaction of 6-(p-methoxyphenyl) fulvene (1a), 6-(3,4-dimethoxyphenyl) fulvene (1b) and 6-(3,4,5-trimethoxyphenyl) fulvene (1c) with LiBEt₃H, lithiated cyclopentadienide intermediates (2a-c) were synthesised. These intermediates were then transmetallated to molybdocene using MoCl₄ (synthesized in situ) to yield the benzyl-substituted molybdocenes bis-[(p-methoxybenzyl)cyclopentadienyl] molybdenum (IV) dichloride (3a), bis-[(3,4-dimethoxybenzyl)cyclopentadienyl] molybdenum (IV) dichloride (3b), and bis-[(3,4,5-trimethoxybenzyl)cyclopentadienyl] molybdenum (IV) dichloride (3c). The molybdocene 3a was characterised by single crystal X-ray diffraction. All three molybdocenes had their cytotoxicity investigated through MTT based preliminary in vitro testing on the human renal cell line Caki-1 in order to determine their IC50 values and compare them with the corresponding titanocene and vanadocene dichloride derivatives. Molybdocenes 3b-c were found to have the same IC50 values of 290 μM, while 3a yielded a value of 84 μM, respectively     

Synthesis of 3-Aminoimidazo[4,5-c]pyrazole Nucleoside via the N-N Bond Formation Strategy as a [5:5] Fused Analog of Adenosine

3-Amino-6-(β-D-ribofuranosyl)imidazo[4,5-c]pyrazole (2) was synthesized via an N-N bond formation strategy by a mononuclear heterocyclic rearrangement (MHR). A series of 5-amino-1-(5-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-β-D-ribofuranosyl-4-(1,2,4-oxadiazol-3-yl)imidaz-oles (6a-d), with different substituents at the 5-position of the 1,2,4-oxadiazole, were synthesized from 5-amino-1-(β-D-ribofuranosyl)imidazole-4-carboxamide (AICA Ribose, 3). It was found that 5-amino-1-(5-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-β-D-ribofuranosyl)-4-(5-methyl-1,2,4-oxadiazol-3-yl)imidazole (6a) underwent the MHR with sodium hydride in DMF or DMSO to afford the corresponding 3-acetamidoimidazo[4,5-c]pyrazole nucleoside(s) (7b and/or 7a) in good yields. A direct removal of the acetyl group from 3-acetamidoimidazo[4,5-c]pyrazoles under numerous conditions was unsuccessful. Subsequent protecting group manipulations afforded the desired 3-amino-6-(β-D-ribofuranosyl)imidazo[4,5-c]pyrazole (2) as a 5:5 fused analog of adenosine (1).     

Ribosylation of the Base Residue of Inosine Derivatives by Phase-Transfer Catalysis

Abstract

Reaction of 2′,3′,5′-O-silylated inosine derivative 1 with 2, 3-O-isopropylidene-5-O-tritylribosyl chloride (3) in a two-phase (CH₂Cl₂-aq. NaOH) system in the presence of Bu₄NBr gave three products, i. e., 6-O-α-, 6-O-β-, and N ¹-β-isomers of glycosides 4, 5a, and 5b. A similar PTC reaction of 1 with 2, 3, 5-tri-O-benzylribosyl bromide (9) gave four regio- and stereo-isomers involving the N¹-β-glycoside 10. Reaction of 1 with 2, 3, 5-tri-O-benzoylribosyl bromide (11) afforded three products involving the desired N¹-β-glycoside 12b, which could be deprotected to give N ¹-ribosylinosine (15b) as a useful intermediate for the synthesis of cIDPR.