scholarly journals Thioether-Catalysed Tandem Synthesis of Furans and Cyclic Ethers or Lactones

Synlett ◽  
2017 ◽  
Vol 28 (11) ◽  
pp. 1358-1362 ◽  
Author(s):  
J. Clark ◽  
Verena Klaus
Keyword(s):  
Carboxylic Acid ◽  
Cyclic Ether ◽  
Single Step ◽  
Cyclic Ethers ◽  
The Creation ◽  
Tandem Synthesis

Acyclic conjugated ynenediones tethered to an alcohol or carboxylic acid are converted into furanyl-substituted cyclic ethers or lactones in a single step by treatment with the tetrahydrothiophene. Modest levels of diastereocontrol can be achieved in some cases where the presence of a substituent on the tether results in the creation of a second stereogenic centre upon formation of the cyclic ether or lactone.

Participation of 19-substituents in electrophilic additions to 6,7-unsaturated 5α-cholestane and B-homo 5α-cholestane derivatives; A case of competition between the participation of an ambident neighboring group and external nucleophile attack

1980 ◽  
Vol 45 (2) ◽  
pp. 559-583 ◽  
Author(s):  
Pavel Kočovský ◽  
Ladislav Kohout ◽  
Václav Černý
Keyword(s):  
Perchloric Acid ◽  
Hydrobromic Acid ◽  
Cyclic Ether ◽  
Cyclic Ethers ◽  
Neighboring Group ◽  
Acid Cleavage ◽  
Neighbouring Group Participation ◽  
Aqueous Perchloric Acid ◽  
The Difference ◽  
Electrophilic Additions

Hypobromous acid action upon the 6,7-unsaturated 19-substituted 5α-cholestans Va-Vc results in the formation of two types of products, the cyclic ethers IX as products of 5(O)n participation of the 19-substituent, and the bromohydrins X. All these compounds are formed from the 6α,7α-bromonium ions Va'-Vc'. Under the same conditions the B-homo-5α-cholestane derivatives VIIa-VIIc afforded solely the cyclic ethers XIV as products of 5(O)n participation of the 19-substituent in the cleavage of the bromonium ions VIIa'-VIIc'. Acid cleavage of the 6α,7α-epoxides VIb and VIc with aqueous perchloric acid or hydrobromic acid gave two types of products, i.e. the cyclic ethers XI and the diols XII or bromohydrines XIII. The cyclic ethers XI arise by 5(O)n participation of the 19-substituent. The B-homo-6α, 7α-epoxide VIIIc on cleavage with aqueous perchloric acid have solely the cyclic ether XVc and by treatment with hydrobromic acid VIIIc afforded the mixture of XVc, as the main product, and of the bromohydrin XVIc. Discussed is the similarity of the bromonium ion cleavage with the fission of the corresponding epoxides, the mechanism of these reactions and the difference in the behaviour of the isomeric olefins Ia-c, IIIa-c, Va-c and VIIa-c and epoxides IIb,c, IVb,c, VIb,c and VIIIb,c. The competition between ambident neighbouring group participation and external nucleophile attack is discussed as well as the dependence of the products ratio on the nucleophilicity of the attacking species.

Cyclic ether synthesis from diols using trimethyl phosphate

2017 ◽  
Vol 53 (35) ◽  
pp. 4787-4790 ◽  
Author(s):  
Shota Asai ◽  
Maho Kato ◽  
Yasunari Monguchi ◽  
Hironao Sajiki ◽  
Yoshinari Sawama
Keyword(s):  
Room Temperature ◽  
Cyclic Ether ◽  
Cyclic Ethers ◽  
Trimethyl Phosphate ◽  
Ether Synthesis

Cyclic ethers are simply synthesized from diols by using trimethyl phosphate at room temperature.

Flavonoid intermediates for the synthesis of mopanol trimethyl ether[trans-trans-7,7',8'-Trimethoxyisochromano(4',3':2,3)chroman-4-ol]

1976 ◽  
Vol 29 (1) ◽  
pp. 191 ◽  
Author(s):  
JW Clark-Lewis ◽  
DP Cox
Keyword(s):  
Carboxylic Acid ◽  
Potassium Carbonate ◽  
Dimethyl Sulphate ◽  
Metal Hydrides ◽  
Cyclic Ether ◽  
Protecting Group ◽  
Model Compounds ◽  
Initial Product ◽  
Dibenzyl Ether ◽  
Trimethyl Ether

Preparation of a number of intermediates for the synthesis of (�)-mopanol trimethyl ether is described, together with exploratory reactions with model compounds, and especially with 7-methoxyflavanone-2'-carboxylic acid. 7-Methoxyflavan-4-ol, the initial product from reduction of 7-methoxyflavanone-2'-carboxylic acid with complex metal hydrides, was found to undergo facile dehydration to a novel intramolecular dibenzyl ether [the cyclic ether (19)*]. It was noted that the methoxymethyl group, which may be used as a protecting group for phenols, did not survive the conditions of methylation with dimethyl sulphate and potassium carbonate in acetone.

scholarly journals C(sp3)-H alkenylation promoted by uranyl cation as a visible-light photocatalyst

2021 ◽  
Vol 2079 (1) ◽  
pp. 012020
Author(s):  
Zhiyu Feng
Keyword(s):  
Hydrogen Atom ◽  
Visible Light ◽  
Bond Formation ◽  
Cyclic Ether ◽  
Hydrogen Atom Transfer ◽  
Cyclic Ethers ◽  
Atom Transfer ◽  
Target Product ◽  
Visible Light Photocatalyst ◽  
Uranyl Cation

Abstract The alkenylation of cyclic ethers with β-nitroalkenes using uranyl cation as a photocatalyst is reported. Previous studies revealed the feasibility of incorporating organic photocatalyst in the visible light mediated alkenylation, while the uranyl cation serves as an alternative photocatalyst candidate successfully accomplish this transformation through a different pathway. The reaction features the direct hydrogen atom transfer (HAT) process to activate alpha C(sp3)-H of cyclic ether, and consequently cyclic ether is coupled with β-nitroalkene to give the target product with F-selectivity through C-C bond formation.

scholarly journals A Potentially Useful Procedure for Conversion of Ethers to Esters

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Li H ◽  
Mark Z ◽  
Graylion M ◽  
Shen T
Keyword(s):  
Building Blocks ◽  
Cyclic Ether ◽  
Gas Chromatography Mass Spectrometry ◽  
High Yield ◽  
Infrared Spectrometry ◽  
Cyclic Ethers ◽  
Efficient Procedure ◽  
Nuclear Magnetic Resonance Spectrometry ◽  
Magnetic Resonance Spectrometry ◽  
Reaction Processes

This communication reports a catalytic system for transformation of ethers into their corresponding esters, especially for cyclic ethers. This efficient procedure was developed as part of our efforts to synthesize nucleoside building blocks and their derivatives. Gas Chromatography-Mass Spectrometry (GC-MS) monitored the reaction processes, Nuclear Magnetic Resonance Spectrometry (NMR), and Infrared Spectrometry (IR) were used to verify the structure of the products. The conversions of Tetrahydrofuran (THF) and other cyclic ether into lactones were accomplished in high yield, over 95%. This approach could be extended too many types of ethers to produce directly corresponding esters simply. Four representatives of ethers were investigated. Cyclic ethers have the higher yields. Linear ethers gave lower yields. The reaction on methoxylcarbon or methyl ether carbon was not observed. The reacted catalyst can be reused over several times. For each reusing, only drops of sulfuric acid need to be added. Nevertheless, the asymmetric ethers selectivity needs to be addressed in future studies.

Development of Noncircular Wheel “TFW” for Traveling over a Single Step only by Rotational Movement

2013 ◽  
Vol 25 (2) ◽  
pp. 375-383
Author(s):  
Tomohiko Oki ◽  
◽  
Toshio Morita
Keyword(s):  
Experimental Model ◽  
Low Cost ◽  
Single Step ◽  
Rotational Movement ◽  
Movement Mechanism ◽  
Internal Mechanism ◽  
The Creation ◽  
Wheeled Vehicles ◽  
Outer Circumference

Wheeled vehicles are used daily because they have high movement efficiency, simple structures and low cost. However, their travel ranges may be limited due to the low traveling performance of wheels when they encounter a step. Variousmovement mechanisms have been developed to solve this issue, but they have become complicated and heavy in attempts to meet each design condition, so they are hard to use daily in some cases. The authors therefore devised a simple, low cost movement mechanism the TFW(Transformable Flexible Wheel) that can travel over a step without special controls. This is a noncircular wheel that can travel over a step without slipping by denting the outer circumference of the wheel when it comes into contact with a step and catching the step with the internal mechanism of the TFW. In this paper, the outline of the structure and movement of the TFW is discussed. In addition, its effectiveness is verified through the creation of two vehicles, the simple prototype SRIDERzero and the experimental model SRIDER, to prove that the traveling performance of the TFW over a step is superior to that of conventional wheels and to demonstrate the basic movements of the TFW.

scholarly journals Polymerization of Cyclic Ethers Initiated by the Reaction of Cyclic Ether with Hexafluoropropylene Oxide.

2002 ◽  
pp. 365-369 ◽  
Author(s):  
Yasuyuki MASUBUCHI ◽  
Tokio HAGIWARA ◽  
Youichi IKEGAYA ◽  
Seiji KAWATA ◽  
Noriyuki YONEZAWA
Keyword(s):  
Cyclic Ether ◽  
Cyclic Ethers ◽  
Hexafluoropropylene Oxide

Enantioselective Synthesis of Lactones and Cyclic Ethers

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Hydroxy Acid ◽  
Addition Product ◽  
Single Step ◽  
Indian Institute ◽  
Cyclic Ethers ◽  
University Of Texas ◽  
Complementary Approach ◽  
Stereogenic Centers ◽  
The University ◽  
Work Up

Developments in organocatalysis have turned toward the enantioselective construction of lactones. Shi-Wei Luo and Liu-Zhu Gong of the University of Science and Technology of China have found (J. Org. Chem. 2007, 71, 9905) that catalyzed addition of acetone to an α-hydroxy acid 1 proceeded with high ee. Esterification of the addition product followed by reduction and acid work-up delivered the lactone 4 with high dr and ee. In a complementary approach, Jean-Marc Vincent and Yannick Landais of the University Bourdeaux-1 showed (Chem. Commun. 2007, 4782) that catalyzed condensation of an aldehyde with an α-hydroxy acid 5 delivered the tetronic acid 8 in high ee. It may be that 8 could also be reduced with useful selectivity. Cong-Gui Zhao of the University of Texas, San Antonio has devised conditions (Organic Lett. 2007, 9, 2745) for the condensation of the keto phosphonates such as 10 with aldehydes to give, after oxidation, the δ-lactone 12. Carbohydrates such as glucose 13 are inexpensive, molecularly-complex starting materials. Subhash Chandra Taneja of the Indian Institute of Integrative Medicine, Jammu Tawi, has found conditions (J. Org. Chem. 2007, 72, 8965) for the single-step I2 -catalyzed transformation of 13 to 14, in which each of the alcohols have been differentiated. In a complementary approach described (Tetrahedron Lett. 2007, 48, 6389) by Tushar Kanti Chakraborty of the Indian Institute of Chemical Technology, Hyderabad, Ti-mediated reduction of 15 was shown to be highly diastereoselective, setting the two new stereogenic centers (marked by*) in 16. Building on work by Mead, Daniel Romo of Texas A&M has shown (J. Org. Chem. 2007, 72, 9053) that reductive cyclization of 18 also proceeded with high diastereocontrol, to give 19. As illustrated by the conversion of 20 to 21 reported (Tetrahedron Lett. 2007, 48, 7351) by Zsuzsa Juhász and László Somsák of the University of Debrecen, six-membered ring cyclic ethers can also be formed from carbohydrate precursors. Richard E. Taylor of the University of Notre Dame has taken advantage (Angew. Chem. Int. Ed. 2007, 46, 6874) of the “chemical chameleon” nature of a sulfone, using it both the stablilize the anion for intramolecular alkylation, to form 23, and as a leaving group, leading to 24.

A Single Step Fractionation of Lignocellulose in Aqueous Solutions of a Carboxylic Acid‐Functionalized Ionic Liquid

2019 ◽  
Vol 4 (9) ◽  
pp. 2774-2779
Author(s):  
Long Cai ◽  
Ying Zhang ◽  
Gang Hu ◽  
Yuanlong Guo ◽  
Longming Jin ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Carboxylic Acid ◽  
Aqueous Solutions ◽  
Single Step ◽  
Functionalized Ionic Liquid

Cyclic ether synthesis: sulfenyletherification with benzenesulfenyl chloride/N, N-diisopropylethylamine and sulfenate ester cycloadditions

1987 ◽  
Vol 65 (8) ◽  
pp. 1833-1837 ◽  
Author(s):  
Sudersan M. Tuladhar ◽  
Alex G. Fallis
Keyword(s):  
Cyclic Ether ◽  
Cyclic Ethers ◽  
Nucleophilic Displacement ◽  
Ether Synthesis ◽  
Special Case ◽  
General Method ◽  
Episulfonium Ion

A general method for the formation of the cyclic ethers 9, 10, 13, 14, 16, and 28 and the lactone 30 is described. The procedure employs benzenesulfenyl chloride prepared insitu in acetonitrile and N,N-diisopropylethylamine to generate a thiiranium (episulfonium) ion intermediate from which the cyclic products arise by internal nucleophilic displacement. In the special case of the norbornene alcohols 1 and 2 the oxetanes 5 and 6 are formed by intramolecular sulfenate ester cycloaddition.

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