scholarly journals Direct Stereospecific Synthesis of Unprotected N-H and N-Me Aziridines from Olefins

Science ◽  
2014 ◽  
Vol 343 (6166) ◽  
pp. 61-65 ◽  
Author(s):  
Jawahar L. Jat ◽  
Mahesh P. Paudyal ◽  
Hongyin Gao ◽  
Qing-Long Xu ◽  
Muhammed Yousufuddin ◽  
...  
Keyword(s):  
Natural Products ◽  
Ambient Temperature ◽  
Building Block ◽  
Direct Synthesis ◽  
Stereospecific Synthesis ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
One Pot ◽  
Rhodium Catalysis ◽  
Bioactive Natural Products

Despite the prevalence of the N-H aziridine motif in bioactive natural products and the clear advantages of this unprotected parent structure over N-protected derivatives as a synthetic building block, no practical methods have emerged for direct synthesis of this compound class from unfunctionalized olefins. Here, we present a mild, versatile method for the direct stereospecific conversion of structurally diverse mono-, di-, tri-, and tetrasubstituted olefins to N-H aziridines usingO-(2,4-dinitrophenyl)hydroxylamine (DPH) via homogeneous rhodium catalysis with no external oxidants. This method is operationally simple (i.e., one-pot), scalable, and fast at ambient temperature, furnishing N-H aziridines in good-to-excellent yields. Likewise, N-alkyl aziridines are prepared from N-alkylated DPH derivatives. Quantum-mechanical calculations suggest a plausible Rh-nitrene pathway.

scholarly journals Isolation of a Novel Polyketide from Neodidymelliopsis sp.

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3235
Author(s):  
Melissa M. Cadelis ◽  
Hugo Gordon ◽  
Alex Grey ◽  
Soeren Geese ◽  
Daniel R. Mulholland ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Natural Products ◽  
Ambient Temperature ◽  
Crude Extract ◽  
Structure Elucidation ◽  
Fungal Pathogens ◽  
Spectroscopic Techniques ◽  
Bioactive Natural Products

Fungi have become an invaluable source of bioactive natural products, with more than 5 million species of fungi spanning the globe. Fractionation of crude extract of Neodidymelliopsis sp., led to the isolation of a novel polyketide, (2Z)-cillifuranone (1) and five previously reported natural products, (2E)-cillifuranone (2), taiwapyrone (3), xylariolide D (4), pachybasin (5), and N-(5-hydroxypentyl)acetamide (6). It was discovered that (2Z)-cillifuranone (1) was particularly sensitive to ambient temperature and light resulting in isomerisation to (2E)-cillifuranone (2). Structure elucidation of all the natural products were conducted by NMR spectroscopic techniques. The antimicrobial activity of 2, 3, and 5 were evaluated against a variety of bacterial and fungal pathogens. A sodium [1-13C] acetate labelling study was conducted on Neodidymelliopsis sp. and confirmed that pachybasin is biosynthesised through the acetate polyketide pathway.

scholarly journals Stereochemistry of Complex Marine Natural Products by Quantum Mechanical Calculations of NMR Chemical Shifts: Solvent and Conformational Effects on Okadaic Acid

Marine Drugs ◽  
2014 ◽  
Vol 12 (1) ◽  
pp. 176-192 ◽  
Author(s):  
Humberto Domínguez ◽  
Guillermo Crespín ◽  
Adrián Santiago-Benítez ◽  
José Gavín ◽  
Manuel Norte ◽  
...  
Keyword(s):  
Natural Products ◽  
Okadaic Acid ◽  
Marine Natural Products ◽  
Chemical Shifts ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Nmr Chemical Shifts ◽  
Conformational Effects

One-Pot Total Synthesis of Bioactive Natural Products

2017 ◽  
pp. 201-228
Author(s):  
Jiachen Xiang ◽  
Miao Wang ◽  
Yu Sun ◽  
Anxin Wu
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
One Pot ◽  
Bioactive Natural Products

Absolute structural elucidation of natural products-A focus on quantum-mechanical calculations of solid-state CD spectra

Chirality ◽  
2009 ◽  
Vol 21 (1E) ◽  
pp. E181-E201 ◽  
Author(s):  
Gennaro Pescitelli ◽  
Tibor Kurtán ◽  
Ulrich Flörke ◽  
Karsten Krohn
Keyword(s):  
Natural Products ◽  
Solid State ◽  
Structural Elucidation ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Cd Spectra

A Simple, One-Pot Synthesis of Trans-Substituted Spiro [5,5] undecane-1,5,9-triones with Aromatic Aldehydes and Meldrum's Acid as the Starting Materials

2015 ◽  
Vol 68 (10) ◽  
pp. 1599 ◽  
Author(s):  
Jingping Ou-Yang ◽  
Yu Zhao ◽  
Huailei Jiang ◽  
Lingxin Meng ◽  
Xingshu Li ◽  
...  
Keyword(s):  
1H Nmr ◽  
Aromatic Aldehydes ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Meldrum's Acid ◽  
X Ray Diffraction ◽  
Meldrum’S Acid ◽  
Reaction Conditions ◽  
One Pot ◽  
X Ray

A simple, one-pot process for the construction of substituted spiro[5,5]undecane-1,5,9-triones using aromatic aldehydes and Meldrum’s acid, and aniline as a catalyst, is reported. Fifteen compounds were synthesized, and the trans/cis ratios were calculated based on 1H NMR analyses of the unpurified products. Quantum mechanical calculations and X-ray diffraction were undertaken to identify the configuration of compound 2a. The proposed mechanisms for these reactions are presented in this paper. In contrast to previous literature, this method endows excellent diastereoselectivity to a series of trans-substituted derivatives. The method is characterized by its simple operation, commercial availability of all materials, mild reaction conditions and moderate-to-good chemical yields.

scholarly journals “On Water” Sonochemical Multicomponent Synthesis of Novel Bioactive 1,1′-(Aryl)bis(2-(cyclohexylamino)-2-oxoethane-1,1-diyl) Di(alkanoates and benzoates)

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Manouchehr Mamaghani ◽  
Nosrat O. Mahmoodi ◽  
Farhad Shirini ◽  
Abbas Azimi-Roshan ◽  
Azam Monfared
Keyword(s):  
Antibacterial Activity ◽  
Natural Products ◽  
Carboxylic Acid ◽  
Building Block ◽  
Reaction Times ◽  
Multicomponent Synthesis ◽  
One Pot ◽  
Benzoate Derivatives

An expeditious, efficient, and ecofriendly ultrasound-promoted synthesis of a series of novel 1,1′-(aryl)bis(2-(cyclohexylamino)-2-oxoethane-1,1-diyl) di(alkanoate and benzoate) derivatives (6a–k), as useful building block candidates for natural products and drugs, is reported. The target compounds were prepared by the reaction of alkyl or aryl carboxylic acid, various bisaldehydes and isocyanocyclohexane in water using one-pot isocyanide-based multicomponent approach. This efficient protocol without using any catalyst furnished the products in short reaction times (4-5 min) and excellent yields (87–96%). The antibacterial activity of the selected products was also examined. Some products showed promising activities.

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