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1

Article

Aromatic polyketide glycosides from an entomopathogenic fungus, Cordyceps indigotica (2012)

Asai, Teigo ; Yamamoto, Takashi ; Chung, Yu-Ming ; [et al.]

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Language: English

In: Tetrahedron Letters, 2012, Vol.53(3), pp.277-280

Description: A new aromatic polyketide glycoside, indigotide A ( ), was isolated from the culture broth of the entomopathogenic fungus, , along with known cyclic depsipeptides, destruxins A, A , B, B and E ( – ), and a polyketide, NG-393 ( ). Repeated treatment of the . culture broth with 5-azacytidine, a DNA methyltransferase inhibitor, led to the isolation of another new aromatic polyketide glycoside, indigotide ( ).

Keywords: Entomopathogenic Fungi ; Secondary Metabolites ; Polyketides ; DNA Methyltransferase Inhibitor ; Epigenetics ; Chemistry

ISSN: 0040-4039

E-ISSN: 1873-3581

DOI: 10.1016/j.tetlet.2011.10.013

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2

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A convenient synthesis of chiral 2-methylenebenzo[e][1,4]diazepin-5-ones via a one-pot reductive cyclodehydration with retention of chirality (2016)

Sorra, Kumaraswamy ; Lai, Chin-Hung ; Feng, Chun-Yen ; [et al.]

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Language: English

In: Tetrahedron Letters, 26 October 2016, Vol.57(43), pp.4842-4844

Description: Total synthesis of optically pure (+)-Fuligocandin A from -proline has been achieved in 29% overall yield. The key step, one-pot reductive cyclodehydration of the chiral 2-nitrophenyl-1,3-dicarbonyl compound, proceeds with 〉98% retention of configuration. This method represents a convenient approach to the synthesis of 2-methylenebenzo[ ][1,4]diazepin-5-ones containing one chiral center. A series of benzo[ ][1,4]diazepin-5-one derivatives have been successfully synthesized with retention of chirality by the one-pot reaction developed in this work. A possible reductive cyclodehydration mechanism was also proposed.

Keywords: (+)-Fuligocandin ; 2-Methylenebenzo[E][1,4]Diazepin-5-One ; Vinylogous Amide ; One-Pot Reductive Cyclodehydration ; Chemistry

ISSN: 0040-4039

E-ISSN: 1873-3581

DOI: 10.1016/j.tetlet.2016.09.060

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3

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Discovery of the first non-planar flavonoid that can strongly inhibit xanthine oxidase: protoapigenone 1′-O-propargyl ether (2013)

Hunyadi, Attila ; Martins, Ana ; Danko, Balazs ; [et al.]

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Language: English

In: Tetrahedron Letters, 27 November 2013, Vol.54(48), pp.6529-6532

Description: Xanthine oxidase (XO) is a key enzyme in purine metabolism with an important role in various pathologies. Several flavonoids have been reported for their capacity to inhibit this enzyme, and, for these compounds, the ability to adopt a planar 3D structure has been accepted as fundamental prerequisite for such activity. Here we report the in vitro investigation of a series of non-planar protoflavone derivatives as XO inhibitors, among which protoapigenone 1′- -propargyl ether was found to be an efficient competitive inhibitor of the enzyme with an IC value of 3.61 μM, significantly ( 〈0.001) stronger than the anti-gout drug allopurinol (IC = 8.72 μM). Methoxy substitution at C-7, however, resulted in complete loss of activity. In silico docking supported the observed structure–activity relationships, based on which a ‘planar structure’ itself can no longer be considered as a criterion for flavonoid-type inhibitors of XO.

Keywords: Xanthine Oxidase Inhibitor ; Flavonoid ; Protoflavone ; Protoapigenone ; Structure–Activity Relationships ; Docking Study ; Chemistry

ISSN: 0040-4039

E-ISSN: 1873-3581

DOI: 10.1016/j.tetlet.2013.09.087

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4

Article

Synthesis of tetrahydroanthracen-9-ones by the domino aldol condensation/Diels–Alder cycloaddition (2012)

Chang, Meng-Yang ; Wu, Ming-Hao

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Language: English

In: Tetrahedron Letters, 20 June 2012, Vol.53(25), pp.3173-3177

Description: A facile protocol toward several substituted 3-aryl-3,4,4a,10-tetrahydro-2 -anthracen-9-ones starting with substituted 2-allylbenzaldehydes was described. The overall synthetic process was carried out by the domino aldol condensation/Diels–Alder cycloaddition of skeleton with substituted cinnamaldehydes in an alkalic aqueous-methanolic solution followed by base-induced double migration of the resulting cycloadducts. Skeleton was prepared from isovanillin ( ) in moderate yield in five-steps via the known procedures with the synthetic sequence of O-allylation, Claisen rearrangement, O-methylation, Grignard methylation, and PCC-mediated oxidation.

Keywords: Claisen Rearrangement ; Aldol Condensation ; Diels–Alder Cycloaddition ; One-Pot Combination ; Tetrahydroanthracen-9-Ones ; Chemistry

ISSN: 0040-4039

E-ISSN: 1873-3581

DOI: 10.1016/j.tetlet.2012.04.053

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5

Article

Synthesis of 1,5-diphenylpent-3-en-1-yne derivatives utilizing an aqueous B-alkyl Suzuki cross coupling reaction (2013)

Chuang, Da-Wei ; El-Shazly, Mohamed ; Chen, Chin-Chau ; [et al.]

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Language: English

In: Tetrahedron Letters, 18 September 2013, Vol.54(38), pp.5162-5166

Description: 1,5-Diphenylpent-3-en-1-yne derivatives were isolated in minor quantities from terrestrial plants and exhibited strong anti-inflammatory activity. A cross coupling reaction between -benzyl-9-BBN and chloroenynes under mild condition was developed resulting in the formation of different 1,5-diphenylpent-3-en-1-yne derivatives with a full control on the / selectivity. Several substrates bearing electron-donating and electron-withdrawing substituents were tolerable under the reaction conditions affording the corresponding products in good yields. This is the first study to report the synthesis of a vast array of novel 1,5-diphenylpent-3-en-1-yne derivatives paving the way for the preparation of tailored derivatives on mass scale necessary for biological studies and drug development.

Keywords: Henna ; Palladium ; B-Benzyl-9-Bbn ; B-Alkyl Suzuki Coupling ; Aqueous Reaction ; Chemistry

ISSN: 0040-4039

E-ISSN: 1873-3581

DOI: 10.1016/j.tetlet.2013.07.020

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6

Article

Kuroshines A and B, new alkaloids from Zoanthus kuroshio (2014)

Cheng, Yuan-Bin ; Lan, Chih-Chin ; Liu, Wei-Chun ; [et al.]

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Language: English

In: Tetrahedron Letters, 24 September 2014, Vol.55(39), pp.5369-5372

Description: A chemical investigation of has yielded two new alkaloids, kuroshines A ( ) and B ( ). The compounds possess a densely functionalized ring system on the basis of the zoanthamine frames. The structures of and were elucidated through interpretation of spectroscopic methods, especially 2D NMR techniques (COSY, HMQC, HMBC, and ROESY). The absolute stereochemistry of was further confirmed by an X-ray single crystallographic analysis using a mirror Cu-Kα radiation.

Keywords: Zoanthus Kuroshio ; Alkaloids ; Marine Natural Products ; Kuroshine ; Chemistry

ISSN: 0040-4039

E-ISSN: 1873-3581

DOI: 10.1016/j.tetlet.2014.07.101

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Article

Bafilomycin M, a new cytotoxic bafilomycin produced by a Streptomyces sp. isolated from a marine sponge Theonella sp (2016)

Chen, Yu-Hsin ; Lu, Mei-Chin ; Chung, Hsu-Ming ; [et al.]

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Language: English

In: Tetrahedron Letters, 26 October 2016, Vol.57(43), pp.4863-4865

Description: A new 16-membered diene macrolide, bafilomycin M ( ), was produced from a sp. GIC10-1, which was originally isolated from a marine sponge sp. The structure of was established by spectroscopic methods and this compound was found to exhibit cytotoxicity toward K-562, HL-60, SUPT-1, and LNCaP tumor cells with IC values 0.060, 0.011, 0.047, and 0.389 μg/mL, respectively.

Keywords: Bafilomycin ; Streptomyces ; Theonella ; Cytotoxicity ; Chemistry

ISSN: 0040-4039

E-ISSN: 1873-3581

DOI: 10.1016/j.tetlet.2016.09.066

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8

Article

One-pot synthesis of aryl biaryl sulfones (2013)

Chang, Meng-Yang ; Wu, Ming-Hao ; Chan, Chieh-Kai ; [et al.]

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Language: English

In: Tetrahedron Letters, 11 December 2013, Vol.54(50), pp.6971-6974

Description: Synthesis of aryl biaryl sulfones with good yields is described. The one-pot efficient synthetic route is carried by the NaH-mediated tandem [C3+C3] annulations of cinnamaldehydes and propargylic sulfones under the boiling THF conditions.

Keywords: One-Pot Synthesis ; Aryl Biaryl Sulfones ; Cinnamaldehydes ; Propargylic Sulfones ; Chemistry

ISSN: 0040-4039

E-ISSN: 1873-3581

DOI: 10.1016/j.tetlet.2013.10.067

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9

Article

Facile synthesis of substituted isoquinolines (2012)

Chang, Meng-Yang ; Wu, Ming-Hao ; Lee, Nein-Chia ; [et al.]

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Language: English

In: Tetrahedron Letters, 18 April 2012, Vol.53(16), pp.2125-2128

Description: A facile three-step protocol toward methoxy isoquinolines starting with substituted 2-allylbenzaldehydes was described. The overall synthetic process of skeleton was carried out using the Grignard addition, PCC-oxidation, and one-pot oxidative cleavage of the olefinic group of skeleton with OsO –NaIO followed by the condensation of the resulting 1,5-dicarbonyl compounds with NH OAc. Skeleton was prepared in high yield via the known Claisen rearrangement of skeleton and O-methylation. Papaverine is also synthesized via the simple three-step synthetic protocol.

Keywords: Isoquinoline ; Claisen Rearrangement ; One-Pot Combination Reaction ; Papaverine ; Chemistry

ISSN: 0040-4039

E-ISSN: 1873-3581

DOI: 10.1016/j.tetlet.2012.02.045

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10

Article

Cladieunicellins R and S, new eunicellins from the Formosan octocoral Cladiella tuberculosa (2016)

Peng, Kai-Yu ; Chen, Nan-Fu ; Chen, Zhi-Cheng ; [et al.]

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Language: English

In: Tetrahedron Letters, 14 September 2016, Vol.57(37), pp.4239-4242

Description: Two new eunicellin-type diterpenoids, cladieunicellins R ( ) and S ( ), were isolated from the octocoral and their structures were elucidated by spectroscopic methods. Eunicellin was proven to be the first 2,6-hemiketal eunicellin and was found to exhibit moderate cytotoxicity toward the MOLT-4, K562, and SUP-T1 cells.

Keywords: Cladiella Tuberculosa ; Eunicellin ; Cladieunicellin ; Cytotoxicity ; Chemistry

ISSN: 0040-4039

E-ISSN: 1873-3581

DOI: 10.1016/j.tetlet.2016.08.028

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Kooperativer Bibliotheksverbund

Berlin Brandenburg