scholarly journals A Biomimetic Synthetic Approach to the Frondosins

2016 ◽  
Vol 69 (12) ◽  
pp. 1420 ◽  
Author(s):  
Kevin K. W. Kuan ◽  
Aylin M. C. Hirschvogel ◽  
Jonathan H. George
Keyword(s):  
Marine Sponge ◽  
Ring Expansion ◽  
Cascade Reaction ◽  
Ring System ◽  
Biomimetic Synthesis ◽  
Synthetic Approach ◽  
Compelling Evidence

The frondosins are a family of five marine sponge-derived meroterpenoids. We propose that the 6–7 ring system common to each of the frondosins is biosynthesized via ring expansion of a 6–6 ring system. Compelling evidence in favour of this proposal was obtained in the form of a biomimetic synthesis of the frondosin 6–7 ring system, which features a highly stereo- and regio-selective ring expansion cascade reaction as the key step.

A Biomimetic Synthesis-Enabled Stereochemical Assignment of Rhodotomentones A and B, Two Unusual Caryophyllene-Derived Meroterpenoids from Rhodomyrtus tomentosa

2021 ◽  
Author(s):  
Lu-Ming Deng ◽  
Li-Jun Hu ◽  
Wei Tang ◽  
Jia-Xin Liu ◽  
Xiao-Jun Huang ◽  
...  
Keyword(s):  
Ring System ◽  
Biomimetic Synthesis ◽  
Stereochemical Assignment ◽  
Rhodomyrtus Tomentosa

Rhodotomentones A and B (1 and 2), two unusual caryophyllene-derived meroterpenoids (CDMTs) featuring a rare 6/6/9/4/6/6 hexacyclic ring system, along with their biogenetically-related CDMTs 7 and 12–15, were isolated from...

scholarly journals Biomimetic Synthesis of Hitorins A and B via an Intermolecular Alkoxy Radical-Olefin Coupling Cascade

2019 ◽  
Author(s):  
Xiaohuan Li ◽  
Tianran Zhai ◽  
Ping He ◽  
Zheng Wei ◽  
Zhang Wang
Keyword(s):  
Cascade Reaction ◽  
Oxidative Cleavage ◽  
Experimental Results ◽  
Biomimetic Synthesis ◽  
Alkoxy Radical ◽  
Radical Oxidation ◽  
Olefin Coupling ◽  
Radical Cascade ◽  
Grob Fragmentation

A biomimetic synthesis of hitorins A and B was achieved based on our modified biosynthetic proposal. In our synthesis, a radical cascade reaction between an alkoxy radical, generated from a hydroperoxide, and a monoterpene (+)-sabinene renders the tetrahydrofuran ring of hitorins A and B. In addition, experimental results supported that the oxidative cleavage of the tetrasubstituted olefin in a key intermediate is via a radical oxidation cascade followed by a Grob fragmentation.<br>

A Synthetic Approach to the Marine Sponge Alkaloids Agelasimine A and Agelasimine B

Heterocycles ◽  
1993 ◽  
Vol 35 (1) ◽  
pp. 143 ◽  
Author(s):  
Tozo Fujii ◽  
Tohru Saito ◽  
Jun Chikazawa ◽  
Yuko Nakamura
Keyword(s):  
Marine Sponge ◽  
Synthetic Approach

scholarly journals New Diterpenes with a Fused 6-5-6-6 Ring System Isolated from the Marine Sponge-Derived Fungus Trichoderma harzianum

Marine Drugs ◽  
2019 ◽  
Vol 17 (8) ◽  
pp. 480 ◽  
Author(s):  
Takeshi Yamada ◽  
Ayano Fujii ◽  
Takashi Kikuchi
Keyword(s):  
Mass Spectrometry ◽  
Marine Sponge ◽  
Trichoderma Harzianum ◽  
Fast Atom Bombardment ◽  
2D Nmr ◽  
Cd Spectroscopy ◽  
Ring System ◽  
Chemical Structures ◽  
Modified Mosher’S Method ◽  
Halichondria Okadai

New diterpenes, namely, trichodermanins F–H, with a fused 6-5-6-6 ring system were isolated from the fungus Trichoderma harzianum OUPS-111D-4 separated from a marine sponge Halichondria okadai. These chemical structures were elucidated by 1D and 2D NMR as well as high-resolution fast atom bombardment mass spectrometry (HRFABMS) spectral analyses. We established their absolute stereostructures by application of the modified Mosher’s method or circular dichroism (CD) spectroscopy. In addition, their cytotoxicities were assessed using several cancer cell lines, with 1 and 2 exhibiting modest activities.

Synthetic studies related to mycobactins. III. Approaches to the synthesis of the cobactin ring system

1972 ◽  
Vol 25 (11) ◽  
pp. 2429 ◽  
Author(s):  
DSC Black ◽  
RFC Brown ◽  
AM Wade
Keyword(s):  
Primary Amine ◽  
Ring Expansion ◽  
Hydroxamic Acids ◽  
Ring System ◽  
Ethyl Benzoate ◽  
Yield Reduction ◽  
Similar Reaction ◽  
Oxidation Reactions ◽  
Cyclic Hydroxamic Acids ◽  
Synthetic Studies

The synthesis of several seven-membered cyclic hydroxamic acids has been carried out in low yield. Reduction of diethyl 2-hydroxyiminoheptane-l,7-dioate afforded ethyl 1-hydroxy-7-oxohexahydroazepine-2-carboxylate, together with related acyclic products. The cobactin precursor 3-bromo-1-hydroxyhexahydro-azepin-2-one was obtained by the ring expansion of 2-bromocyclohexanone with benzenesulphonohydroxamic acid and also by the peracid oxidation of 6-bromo-7-ethoxy-3,4,5,6-tetrahydro-2H-azepine. The methyl and cinnamyl imidates of hexanolactam were oxidized by peracid to 1-hydroxyhexahydroazepin-2-one, in addition to the related imino- and nitroso-hexanoic esters. In a similar reaction, 1-hydroxypiperidin-2-one was obtained from 2-methoxy-3,4,5,6-tetrahydropyridine. During the course of these oxidation reactions, the intermediate oxaziridines 7-methoxy-8-oxa-1-azabicyclo[5,1,0]octane and 6-bromo-7-ethoxy-8-oxa-1-azabicyclo[5,1,0]octane were isolated and identified. The peraoid oxidation of ethyl N-cyclohexylbenzimidate yielded cyclohexylhydroxylamine and ethyl benzoate in reasonable yields. This reaction suggests a useful method for the conversion of a primary amine into the related hydroxylamine.

An Efficient Biomimetic Synthesis of Some Marine Sponge Tyrosine Metabolites

1995 ◽  
Vol 7 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Todd R. Boehlow ◽  
Christopher D. Spilling
Keyword(s):  
Marine Sponge ◽  
Biomimetic Synthesis

ChemInform Abstract: A New Synthetic Approach to the Rotenoid Ring System.

ChemInform ◽  
1990 ◽  
Vol 21 (3) ◽  
Author(s):  
S. M. F. LAI ◽  
J. J. A. ORCHISON ◽  
D. A. WHITING
Keyword(s):  
Ring System ◽  
Synthetic Approach
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