共查询到20条相似文献,搜索用时 15 毫秒
1.
A catalytic hypervalent iodine oxidation of p-dialkoxybenzenes using 4-iodophenoxyacetic acid (1) and 2KHSO5 x KHSO4 x K2SO4 (Oxone) was developed. Reaction of p-dialkoxybenzenes (2) with a catalytic amount of 1 in the presence of Oxone as a co-oxidant in 2,2,2-trifluoroethanol-water (1 : 2) gave the corresponding p-quinones (3) in excellent yields without purification. This procedure was applied to synthesis of blattellaquinone (9), the sex pheromone of the German cockroach, Blattella germanica. 相似文献
2.
Morifumi Fujita 《Tetrahedron letters》2017,58(47):4409-4419
Recent progress in the area of hypervalent iodine-induced enantioselective oxidation is reviewed with emphasis from a mechanistic point of view. Chiral lactate and lactamide sidechains in hypervalent iodine reagents induce herical chirality around the iodine reaction site, which provides a chiral environment suitable for enantioselective transformations. The stereochemical outcomes of alkene oxidation are also compiled and used for systematically understanding the reaction mechanism of oxidative double bond difunctionalization. 相似文献
3.
In 1994, we first determined the single-electron-transfer (SET) oxidation ability of phenyliodine(III) bis(trifluoroacetate) (PIFA) toward phenyl ethers, affording the corresponding aromatic cation radicals. Since then, hypervalent iodine(III) has been utilized as a selective and efficient SET oxidizing agent that enables a variety of direct C-H functionalizations of aromatic rings in electron-rich arenes under mild conditions. We have now extended the original method to work in a series of heteroaromatic compounds such as thiophenes, pyrroles, and indoles. The investigations and results obtained since the start of this century are summarized in this article. 相似文献
4.
Both λ3- and λ5-iodanes have proven to be useful reagents in the oxygenative dearomatization of phenols, and exploitations of their chemistry in the conception of both substrate- and reagent-controlled asymmetric variants of such a transformation of great value for natural product synthesis have shown evident signs of success. Moreover, the use of stabilized IBX (i.e., SIBX) in our methodology for O-demethylation of 2-methoxyphenols, which relies on the same key oxygenating dearomatization event, is reported here to be much more efficacious than that of IBX itself in the chemoselective one-step conversion of homovanillyl alcohol into hydroxytyrosol, and bergenin into norbergenin. 相似文献
5.
Hiromi Hamamoto 《Tetrahedron letters》2004,45(11):2293-2295
The direct aromatic carbon-oxygen bond-formation reaction was described and the novel and simple synthetic method for chroman derivatives involving aromatic cation radical intermediates was developed using the hypervalent iodine(III) reagent, phenyliodine(III) bis(trifluoroacetate) (PIFA). 相似文献
6.
Aromatic and alkyl alcohols were oxidized to the corresponding aldehydes or ketones at room temperature with high conversion and selectivity using Oxone (2KHSOs-KHSO4.K2SO4) as oxidant catalyzed by ruthenium complex Quin-Ru-Quin (where Quin = 8-hydroxyquinoline). The reaction time is very short and the preparation of complex is simple. 相似文献
7.
Aromatic and alkyl alcohols were oxidized to the corresponding aldehydes or ketones at room temperature with high conversion and selectivity using Oxone (2KHSO5·KHSO4·K2SO4) as oxidant catalyzed by ruthenium complex Quin-Ru-Quin (where Quin = 8-hydroxyquinoline). The reaction time is very short and the preparation of complex is simple. 2008 Zi Qiang Lei. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. 相似文献
8.
《Tetrahedron letters》2014,55(31):4370-4372
A mild propargylic oxidation of alkynes is reported using a diacetoxyiodobenzene/tert-butyl hydroperoxide (DIB/TBHP) protocol. The reactions proceed smoothly at 0 °C and a number of α,β-unsaturated alkynoic ketones are obtained. 相似文献
9.
An efficient method was developed for chlorination of aromatic compounds with electron-donating groups using iodobenzene as the catalyst and m-chloroperbenzoic acid as the terminal oxidant in the presence of 4-methylbenzenesulfonic acid in THF at room temperature for 24 h,and a series of the monochlorinated compounds was obtained in good yields.In this protocol,the catalyst iodobenzene was first oxidized into the hypervalent iodine intermediate,which then treated with lithium chloride and finally reacted with aromatic compounds to form the chlorinated compounds. 相似文献
10.
Highly efficient reactions of 4-hydroxycoumarin with hypervalent iodine reagents under mild conditions are described, which give rise to 4-aryloxycoumarins in good to excellent yields. 相似文献
11.
Aurélie Ozanne-Beaudenon 《Tetrahedron letters》2006,47(33):5869-5873
SIBX is a stabilized (i.e., nonexplosive) formulation of the λ5-iodane 2-iodoxybenzoic acid IBX that can be used as a suspension in various organic solvents to oxidize safely sulfides into sulfoxides. Most yields are comparable to those obtained using IBX or other iodanes such as PhIO and PhIO2. An asymmetric version of this SIBX-mediated sulfoxidation was performed in high chemical yield and moderate enantioselectivity by simple addition of an external chiral source. 相似文献
12.
E. Ramakrishna Kapil Dev Saransh Wales Maurya Ibadur Rahman Siddiqui Rakesh Maurya 《Tetrahedron letters》2017,58(6):570-573
We have developed a novel and efficient method for the oxidation of aryl sulfonylhydrazones to N-aroyl-N′-acyl arylsulfonylhydrazides, using hypervalent iodine (III) reagent in good yields at room temperature. 相似文献
13.
Anees Ahmad Paulo Scarassati Nazli Jalalian Berit Olofsson Luiz F. Silva Jr. 《Tetrahedron letters》2013
A novel protocol for the oxidative rearrangement of alkenes using in situ generated hypervalent iodine(III) was developed. This approach uses inexpensive, readily available, and stable chemicals (PhI, mCPBA, and TsOH) giving rearrangement products in yields comparable to those obtained using the more expensive commercially available [hydroxy(tosyloxy)iodo]benzene [HTIB or Koser’s reagent]. Additionally, an alternative protocol for the synthesis of 1-methyl-2-tetralone through the one-step epoxidation/rearrangement of 4-methyl-1,2-dihydronaphthalene using mCPBA and TsOH was developed. 相似文献
14.
Girish PrabhuV.V. Sureshbabu 《Tetrahedron letters》2012,53(32):4232-4234
A simple protocol for the synthesis of 2-amino-1,3,4-oxadiazoles starting from the corresponding acylhydrazides by cyclodesulfurization of intermediate acylthiosemicarbazides mediated by o-iodoxybenzoic acid in good yields has been described. The protocol is mild with wide substrate scope, and thus a range of 2-amino-1,3,4-oxadiazoles have been prepared. 相似文献
15.
《中国化学快报》2021,32(8):2559-2561
An efficient and facile method for C–H amination of quinoxalinones with heteroaromatic amines under metal-free conditions has been described. In the presence of hypervalent PIDA reagent, the desired products with various groups were obtained with moderate to high yields. 相似文献
16.
Varsha Tiwari Vishnu Nayak Badavath Adesh Kumar Singh Jeyakumar Kandasamy 《Tetrahedron letters》2018,59(26):2511-2514
Oxidation of various sugar primary alcohols into corresponding uronic acids was demonstrated using 1-chloro-1,2-benziodoxol-3(1H)-one and TEMPO. The reaction proceeds at room temperature in good to excellent yields. Primary alcohols get oxidized selectively over the secondary alcohols under mild reaction conditions. 相似文献
17.
Oxone, in the presence of a catalytic amount of iron(II) sulfate and graphite oxide, oxidizes efficiently alcohols into their corresponding carboxylic acid or ketone compounds at room temperature in short reaction times and in good to quantitative yields under ultrasonic irradiation. 相似文献
18.
Nucleophilic para-fluorination of substituted anilines to afford 4-fluorocyclohexadieneimine derivatives is achieved in the presence of hypervalent iodine and pyridinium polyhydrogen fluoride. 相似文献
19.
20.
We find that Magtrieve™ (CrO2) catalyzes the oxidation of a wide variety of alcohols with periodic acid as the terminal oxidant. Mild conditions, short reaction times, and facile aqueous work-up make this a most attractive method. Olefins are not oxidized under these conditions; thus alcohols react selectively in the presence of alkenes. Conditions have been optimized with respect to catalyst loading, solvent, and co-oxidant; and the scope of the reaction includes primary and secondary benzylic, allylic, and aliphatic alcohols. 相似文献