Attempts to Mimic Key Bond-Forming Events Associated with the Proposed Biogenesis of the Pentacyclic Lamellarins

2008 ◽  
Vol 61 (2) ◽  
pp. 80 ◽  
Author(s):  
Lorraine C. Axford ◽  
Kate E. Holden ◽  
Katrin Hasse ◽  
Martin G. Banwell ◽  
Wolfgang Steglich ◽  
...  
Keyword(s):  
Carboxy Group ◽  
Pyrrole Ring ◽  
Lactone Ring ◽  
Polymeric Materials ◽  
Isoquinoline Alkaloid ◽  
Oxidative Cyclization ◽  
Analogous Reaction ◽  
Cyclization Reactions ◽  
Reaction Conditions ◽  
Bond Forming

The pyrrole-tethered veratroles 16 and 27 each engage in PIFA-induced oxidative cyclization reactions to give compounds 22 and 29, respectively, which incorporate a key tricyclic fragment associated with the title natural products. In contrast, the corresponding catechols 11 and 12 only produce polymeric materials on subjection to analogous reaction conditions. Efforts to study lactone ring formation by the oxidative cyclization of catechol 30 and veratrole 38 have been thwarted by an inability to prepare the former substrate and decomposition of the latter. The reported conversions 44 → 45 and 46 → 47 suggest that a C2-carboxy group attached to the pyrrole ring can ‘direct’ the oxidative cyclization of N-tethered aryl groups. The acquisition of compound 22 by the means described herein provides an adventitious and concise route to the racemic modification of the pyrrolo[2,1-a]isoquinoline alkaloid crispine A (52).

PIFA-Mediated Oxidative Cyclization Reactions of α-Acyl Acrylamides: A Synthetic Route to Substituted Isoxazol-3(2H)-ones

Synthesis ◽  
2018 ◽  
Vol 50 (09) ◽  
pp. 1875-1882 ◽  
Author(s):  
Rui Zhang ◽  
Dewen Dong ◽  
Jingwen Yuan ◽  
Chitturi Rao ◽  
Qian Zhang ◽  
...  
Keyword(s):  
Intramolecular Cyclization ◽  
Oxidative Cyclization ◽  
Metal Catalyst ◽  
Synthetic Route ◽  
Cyclization Reactions ◽  
Reaction Conditions ◽  
Catalyst Free ◽  
Free Oxidation

An intramolecular cyclization of various α-acyl β-amino acrylamides in the presence of PIFA and TFA is described. This transformation features mild reaction conditions, simple execution, high chemo­selectivity, and metal catalyst-free oxidation, and thereby, provides not only an alternative protocol for the construction of N–O bond, but also an efficient and straightforward synthesis of substituted isoxazol-3(2H)-ones from readily available α-acyl acrylamides.

scholarly journals Pt(II)-Decorated Covalent Organic Framework for Photocatalytic Difluoroalkylation and Oxidative Cyclization Reactions

2021 ◽  
Vol 13 (5) ◽  
pp. 6349-6358
Author(s):  
Zainab Almansaf ◽  
Jiyun Hu ◽  
Federica Zanca ◽  
Hamid R. Shahsavari ◽  
Benjamin Kampmeyer ◽  
...  
Keyword(s):  
Oxidative Cyclization ◽  
Cyclization Reactions ◽  
Covalent Organic Framework ◽  
Organic Framework

scholarly journals Oxidative cyclo-rearrangement of helicenes into chiral nanographenes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chengshuo Shen ◽  
Guoli Zhang ◽  
Yongle Ding ◽  
Na Yang ◽  
Fuwei Gan ◽  
...  
Keyword(s):  
Functional Materials ◽  
Optical Devices ◽  
Oxidative Cyclization ◽  
Synthetic Chemistry ◽  
Aromatic Rings ◽  
Cyclization Reactions ◽  
Rearrangement Reaction ◽  
Skeletal Reconstruction ◽  
Gradual Release

AbstractNanographenes are emerging as a distinctive class of functional materials for electronic and optical devices. It is of remarkable significance to enrich the precise synthetic chemistry for these molecules. Herein, we develop a facile strategy to recompose helicenes into chiral nanographenes through a unique oxidative cyclo-rearrangement reaction. Helicenes with 7~9 ortho-fused aromatic rings are firstly oxidized and cyclized, and subsequently rearranged into nanographenes with an unsymmetrical helicoid shape through sequential 1,2-migrations. Such skeletal reconstruction is virtually driven by the gradual release of the strain of the highly distorted helicene skeleton. Importantly, the chirality of the helicene precursor can be integrally inherited by the resulting nanographene. Thus, a series of chiral nanographenes are prepared from a variety of carbohelicenes and heterohelicenes. Moreover, such cyclo-rearrangement reaction can be sequentially or simultaneously associated with conventional oxidative cyclization reactions to ulteriorly enrich the geometry diversity of nanographenes, aiming at innovative properties.

Carbon Dioxide as a Carbon Resource – Recent Trends and Perspectives

2012 ◽  
Vol 67 (10) ◽  
pp. 961-975 ◽  
Author(s):  
Markus Hölscher ◽  
Christoph Gürtler ◽  
Wilhelm Keim ◽  
Thomas E. Müller ◽  
Martina Peters ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Raw Materials ◽  
Low Cost ◽  
Polymeric Materials ◽  
Short Review ◽  
Chemical Research ◽  
Bond Forming ◽  
Bulk Chemicals ◽  
High Thermodynamic Stability ◽  
Recent Trends

With the growing perception of industrialized societies that fossil raw materials are limited resources, academic chemical research and chemical industry have started to introduce novel catalytic technologies which aim at the development of economically competitive processes relying much more strongly on the use of alternative carbon feedstocks. Great interest is given world-wide to carbon dioxide (CO2) as it is part of the global carbon cycle, nontoxic, easily available in sufficient quantities anywhere in the industrialized world, and can be managed technically with ease, and at low cost. In principle carbon dioxide can be used to generate a large variety of synthetic products ranging from bulk chemicals like methanol and formic acid, through polymeric materials, to fine chemicals like aromatic acids useful in the pharmaceutical industry. Owing to the high thermodynamic stability of CO2, the energy constraints of chemical reactions have to be carefully analyzed to select promising processes. Furthermore, the high kinetic barriers for incorporation of CO2 into C-H or C-C bond forming reactions require that any novel transformation of CO2 must inevitably be associated with a novel catalytic technology. This short review comprises a selection of the most recent academic and industrial research developments mainly with regard to innovations in CO2 chemistry in the field of homogeneous catalysis and processes.

scholarly journals The Eschenmoser coupling reaction under continuous-flow conditions

2011 ◽  
Vol 7 ◽  
pp. 1164-1172 ◽  
Author(s):  
Sukhdeep Singh ◽  
J Michael Köhler ◽  
Andreas Schober ◽  
G Alexander Groß
Keyword(s):  
Continuous Flow ◽  
Elevated Temperatures ◽  
Reaction Times ◽  
Coupling Reaction ◽  
Flow Chemistry ◽  
Flow Conditions ◽  
Reaction Conditions ◽  
Bond Forming ◽  
Carbon Carbon Bond ◽  
Reaction Proceeds

The Eschenmoser coupling is a useful carbon–carbon bond forming reaction which has been used in various different synthesis strategies. The reaction proceeds smoothly if S-alkylated ternary thioamides or thiolactames are used. In the case of S-alkylated secondary thioamides or thiolactames, the Eschenmoser coupling needs prolonged reaction times and elevated temperatures to deliver valuable yields. We have used a flow chemistry system to promote the Eschenmoser coupling under enhanced reaction conditions in order to convert the demanding precursors such as S-alkylated secondary thioamides and thiolactames in an efficient way. Under pressurized reaction conditions at about 220 °C, the desired Eschenmoser coupling products were obtained within 70 s residence time. The reaction kinetics was investigated and 15 examples of different building block combinations are given.

scholarly journals Synthesis and Antitumor Activity of a Series of Novel 1-Oxa-4-azaspiro[4,5]deca-6,9-diene-3,8-dione Derivatives

Molecules ◽  
2019 ◽  
Vol 24 (5) ◽  
pp. 936
Author(s):  
Ze Yang ◽  
Qiu Zhong ◽  
Shilong Zheng ◽  
Guangdi Wang ◽  
Ling He
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Cancer Cell ◽  
Cancer Cell Lines ◽  
Oxidative Cyclization ◽  
Human Lung Cancer ◽  
Reaction Conditions ◽  
Promising Candidate ◽  
Metal Catalyzed ◽  
Further Development

A series of novel 1-oxa-4-azaspiro[4.5]deca-6,9-diene-3,8-diones were designed and synthesized by using 4-aminophenol and α-glycolic acid or lactic acid as starting materials in three or four steps. The key step is the metal-catalyzed oxidative cyclization of the amide to 1-oxa-4-azaspiro[4.5]deca-6,9-diene-3,8-diones (10a and 10b), the reaction conditions of which are investigated and optimized. The anticancer activity of 17 1-oxa-4-azaspiro[4.5]deca-6,9-diene-3,8-dione derivatives was evaluated. Preliminary results showed that 15 compounds have moderate to potent activity against human lung cancer A549, human breast cancer MDA-MB-231, and human cervical cancer HeLa cancer cell lines. Among them, compounds 11b and 11h were the most potent against A549 cell line with 0.18 and 0.19 µM of IC50, respectively; compounds 11d, 11h, and 11k showed the most potent cytotoxicity against MDA-MB-231 cell line with 0.08, 0.08, and 0.09 µM of IC50, respectively, while the activities of 11h, 11k, and 12c against HeLa cell line were the most potent with 0.15, 0.14, and 0.14 µM of IC50, respectively. Compound 11h is a promising candidate for further development, which emerged as the most effective compound overall against the three tested cancer cell lines.

Metal-Free Oxidative C(sp3)–N Coupling by HBr and DMSO: A Novel Synthesis of 2,3-Dihydroquinazolin-4(1H)-ones

Synlett ◽  
2018 ◽  
Vol 29 (07) ◽  
pp. 912-917 ◽  
Author(s):  
Parviz Ranjbar ◽  
Narjes Rezaei ◽  
Ehsan Sheikhi
Keyword(s):  
Oxidative Cyclization ◽  
Cyclization Reaction ◽  
Primary Amines ◽  
Isatoic Anhydride ◽  
Reaction Conditions ◽  
Coupling Process ◽  
Benzylic Alcohols ◽  
Metal Free ◽  
Novel Synthesis

A metal-free oxidative C(sp3)–N coupling process has been developed for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones. The reaction between primary amines, isatoic anhydride, and benzylic alcohols in the presence of HBr in DMSO at 80 °C affords 2,3-dihydroquinazolin-4(1H)-ones in excellent yields. Under these reaction conditions, benzylic alcohols react with in situ generated bromodimethylsulfonium bromide to form alkoxysulfonium intermediates. These intermediates undergo an oxidative cyclization reaction with primary amines and isatoic anhydride to produce the title products.

Copper(II)-Promoted Oxidation/[3+2]Cycloaddition/Aromatization Cascade: Efficient Synthesis of Tetrasubstituted NH-Pyrrole from Chalcones and Iminodiacetates

Synlett ◽  
2019 ◽  
Vol 30 (12) ◽  
pp. 1442-1446 ◽  
Author(s):  
Zhang-qi Lin ◽  
Chao-dong Li ◽  
Zi-chun Zhou ◽  
Shuai Xue ◽  
Jian-rong Gao ◽  
...  
Keyword(s):  
Efficient Method ◽  
Cascade Reaction ◽  
Oxidative Cyclization ◽  
Efficient Synthesis ◽  
Reaction Conditions ◽  
Highly Efficient ◽  
Wide Range ◽  
Reaction Proceeds

A simple and highly efficient method for the preparation of tetrasubstituted NH-pyrrole from a wide range of chalcones and diethyl iminodiacetates via a Cu(OAc)2-promoted oxidation/[3+2]cycloaddition/aromatization cascade reaction has been developed. This reaction proceeds through dehydrogenations, deamination, and oxidative cyclization, affording the corresponding products in good to excellent yields. This convenient methodology for constructing tetrasubstituted NH-pyrroles has several advantages over existing methods, such as the use of easily accessible chalcones and readily available diethyl iminodiacetates, and mild reaction conditions. A wide range of substrates are tolerated.

Synthesis of Benzazoles through Electrochemical Oxidative Cyclization Reactions

2020 ◽  
Vol 7 (19) ◽  
pp. 3969-3974
Author(s):  
Qi An ◽  
Chaoyin He ◽  
Xiaodong Fan ◽  
Chuanfu Hou ◽  
Jian Zhao ◽  
...  
Keyword(s):  
Oxidative Cyclization ◽  
Cyclization Reactions
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