ACYLATIVE CLEAVAGE OF CYCLIC ETHERS CATALYZED BY SAMARIUM TRICHLORIDE

Oxiranes as well as four and five membered rings of cyclic ethers were cleaved with acyl chloride in the presence of samarium trichloride or Eu(hfe)_3 as Lewis-acid catalyst under mild conditions,the oorresponding chloroesters were obtained readily and smoothly in excellent yields.

Stabilizing SEI by cyclic ethers toward enhanced K^(+) storage in graphite

The poor cycling stability of graphite in traditional ester electrolyte limits its applications as anodes for potassium ion batteries(KIBs).Herein,we demonstrate that the introduction of cyclic ether co-solvents into ester electrolytes can remarkably enhance the cycling stability of graphite anodes.The graphite anode in ester electrolyte with cyclic ether could achieve a reversible capacity of 196.1 m Ah g^(-1) after 100 cycles at 0.3 C(1 C=280 m A g^(-1)),about three times higher than those in ester electrolytes with or without linear ether.Compared with the SEI formed in ester electrolytes,the addition of tetrahydrofuran promotes the generation of K_(2)CO_(3) and ethylene oxide oligomers(PEO),of which the K_(2)CO_(3) is expected to be more conductive and PEO is mechanically robust.The more uniform,conductive and stable solid electrolyte interphases(SEIs)on graphite in electrolytes with cyclic ethers contribute to the enhancement of the electrochemical performances of graphite.This work provides a novel design of commercialized electrolytes to achieve high-performance anodes for KIBs,which potentially accelerates the development of KIBs.

Sulfamic Acid as a Cost-effective Catalyst for Acetolysis of Cyclic Ethers

Sulfamic acid has been used as an efficient catalyst and green alternative for conventional acidic materials to promote the acetolysis reaction of THF to produce 1, 4-diacetoxybutane. This method is also applicable in the acetolysis of other cyclic ethers, such as methyl substituted THF and tetrahydropyran and 1,4-dioxane which is less reactivity.

Photoredox Synthesis of Thio-Functionalized Cyclic Ethers Using N-Sulfenyl Phthalimides as a Thiyl-Radical Precursor

Comprehensive Summary A visible-light mediated exclusively regioselective synthesis of 2,2-disubstituted thio-functionalized tetrahydrofurans,tetrahydro-pyrans and oxepanes has been described through an operationally simple and mild photoredox protocol.Thiyl radical generated from N-phenylsulfenyl phthalimide by photoredox catalysis was proven to be the key reactive intermediate in this reaction.

Palladium-catalyzed annulative allylic alkylation for regioselective construction of indole-fused medium-sized cyclic etherS

A new palladium-catalyzed annulative allylic alkylation(AAA)reaction of 2-(indol-2-yl)phenols with dual allylic electrophiles such as isobutylene dicarbonate and butene dicarbonate is described,leading to the regioselective synthesis of tetracyclic medium-sized cyclic ethers possessing a bridged aryl-indole scaf-fold,namely,benzo[2,3]oxocino[4,5-b]indoles and benzo[2,3]oxepino[4,5-b]indoles,in good to excellent yields.This protocol demonstrates a broad substrate scope,good compatibility with substituents and high regioselectivity,providing a catalytic and flexible method for creating bridged aryl-indole skeletons.

Deconstrutive Difunctionalizations of Cyclic Ethers Enabled by Difluorocarbene to Access Difluoromethyl Ethers

An unprecedented difluorocarbene-mediated C-O bond cleavage of cyclic ethers for the construction of difluoromethyl ethers is herein disclosed.This protocol is distinguished by its mild conditions,high efficiency,and wide substrate scope,which can tolerate both sensitive functional groups such as the hydroxyl group,olefin and C-C triple bonds,as well as complex molecules.It thus demonstrates excellent chemoselectivities and great potential for late-stage modification of pharmaceutical compounds and natural products.It is worth noting that this method not only introduces fluorine atoms into the final molecules,but it can also effectively form an ester or ether linkage.

Studies on sulfinatodehalogenation——XVIII. The reaction of perfluoroalkyl iodides with α-methylene cyclic ethers

Perfluoroalkyl iodides reacted with various a-methylene oxacycloalkanes in the presence of sodium dithionite to give ring opening adducts. The reaction provided an efficient method for the syntheses of polyfunctional organofluorine compounds.

Synthesis of Novel Cyclic Aryl Ether Thioether Ketone (Sulfone) Oligomers

Two kinds of macrocyclic oligomers containing aromatic sulfide linkages have been synthesized by the solution polycondensation in high yield. The cyclic compounds were characterized by H-1 and C-13 NMR, by and MALDI - TOF MS.

CATIONIC RING-OPENING POLYMERIZATION OF TETRAHYDROFURAN WITH KEGGIN-TYPE HETEROPOLYCOMPOUNDS AS SOLID ACID CATALYSTS

Three Keggin-type heteropolyanions, namely H3PMo12O40-13H2O, （NH4）3PMo12O40·4H2O and H3PW12O40·13H2O were prepared and tested in the ring-opening polymerization reaction of tetrahydrofuran. The effects of the counter-cation （H＋, NH4＋） and the peripheral atoms （Mo, W） on the polymerization were investigated. It has been found that when the protons of H3PMo12O40·13H2O were replaced by the ammonium cations the polymerization rate decreased dramatically. Whereas, when the peripheral atoms （Mo） were replaced by their homologous （W）, the polymerization rate increased twofold. As for the viscosity average molecular weight （My） of polymer products, it was found that the high molecular weight （7930） was obtained by using H3PW12O40·13H2O. The molecular weight （My） obtained by H3PMo12O40·13H2O and （NH4）H3PMo12O40·13H2O was 6470 and 6810, respectively.

Zirconyl Chloride Promoted Highly Efficient Domino Synthesis of New 1, 2, 3, 4-Tetrahydroquinoline Derivatives in Water

The tetrahydroquinoline moiety is a structural feature of many natural products. By using a domino reaction of aromatic amines and cyclic enol ethers catalyzed by zirconyl chloride in water, various tetrahydroquinoline derivatives were synthesized efficiently. Most cyclized products showed cis selectivity. The cis selectivity was tentatively rationalized due to chelation control in water.

Structure of Palisadin B,C_(15)H_(24)Br_2O

Palisadin B,a brominated sesquiterpenoid, was isolated from the marine alga genus Laurencia Karlae Zhang et Xia collected from the Nansha Islands of the South China Sea. The structure was examined by MS and NMR spectra and confirmed by X-ray diffraction analysis.C_(15) H_(24) Br_2O, Mr=380.18, tetragonal,P4_12_12, a= 10. 812(3) ,c=27. 436(7),V=3027. 1, Z=8, D_c= 1. 948Mg. m￣(-3) ,μ(MoKa) = 61. 81 cm￣(-1), F(000) =1900,T=296K,final R=0. 050 for 1082 observed reflections. The molecule is composed of a cyclohexane ring fused with a seven-membered cyclic ether, and the latter exhibits a twist boat conformation.The molecules in the crystal lattice are held together by van der Waals forces (m. p.367-368K). Bond lengths and angles are internally consistent and the van der Waals interactions are normal.

Structure of Palisadin B,C15H24Br2O

Palisadin B,a brominated sesquiterpenoid, was isolated from the marine alga genus Laurencia Karlae Zhang et Xia collected from the Nansha Islands of the South China Sea. The structure was examined by MS and NMR spectra and confirmed by X-ray diffraction analysis.C15 H24 Br2O, Mr=380.18, tetragonal,P41212, a= 10. 812（3） ,c=27. 436（7）,V=3027. 1, Z=8, Dc= 1. 948Mg. m￣（-3） ,μ（MoKa） = 61. 81 cm￣（-1）, F（000） =1900,T=296K,final R=0. 050 for 1082 observed reflections. The molecule is composed of a cyclohexane ring fused with a seven-membered cyclic ether, and the latter exhibits a twist boat conformation.The molecules in the crystal lattice are held together by van der Waals forces （m. p.367-368K）. Bond lengths and angles are internally consistent and the van der Waals interactions are normal.