Rhodamine spirolactam sensors operated by sulfur-cooperated metal complexation
New rhodamine Schiff base sensors were developed to improve selective sensing by introducing sulfide, ester, and dithiocarbonate groups, as well as using ketones coupled to rhodamine-hydrazine. Metal sensing proceeded through the 1:1 complexation of the metal ion for most sensors in the presence of Cu2?+ and Hg2?+. A sensor carrying a dithiocarbonate group responded selectively to Hg2?+ showing a strong colorimetric change and intense fluorescence. The association constants of the sensors were determined from a linear plot performed at micro-molar concentrations to afford values in the range of 104. Sensing was interrupted at the initial time of Hg2?+ exposure due to the isomerization of imine and preferential metal bonding of two dithiocarbonate groups regardless of the main structure of rhodamine. The sensors exhibited the reversible and reproducible performance for Hg2?+ sensing.
Radical additions of xanthates to vinyl epoxides and related derivatives: A powerful tool for the modular creation of quaternary centers
(Chemical Equation Presented) An open relationship: The triethylborane/O2-mediated addition of xanthates to vinyl epoxides and derivatives represents an efficient process to form carbon-carbon bonds. Complex structures can be rapidly assembled in a modular, convergent manner, under mild conditions, using readily available reagents (see scheme, Bn = benzyl). The formation of quaternary centers proved especially facile.
Charrier, Nicolas,Gravestock, David,Zard, Samir Z.
Synthesis and reactivity of 2-thionoester pyrroles: A route to 2-formyl pyrroles
2-Functionalised pyrroles exhibit considerable synthetic utility. Herein, the synthesis and reactivity of 2-thionoester (-C(S)OR) pyrroles is reported. 2-Thionoester pyrroles were synthesised using a Knorr-type approach from aliphatic starting materials. 2-Thionoester pyrroles were reduced to the corresponding 2-formyl pyrroles, or the deuterated formyl variant, in one step using RANEY nickel, thereby removing the need for the much-utilised hydrolysis/decarboxylation/formylation steps that are typically required to convert Knorr-type 2-carboxylate pyrroles into 2-formyl pyrroles. 2-Thionoester pyrroles proved tolerant of typical functional group interconversions for which the parent 2-carboxylate pyrroles have become known.
Kim, Min Joon,Gaube, Sophie M.,Beh, Michael H. R.,Smith, Craig D.,Thompson, Alison
p. 31773 - 31780
(2019/10/19)
Efficient Synthesis of N-Benzyloxycarbonyl-2-aminoalkanesulfonyl Chlorides with Functionalized Side Chains
N-Benzyloxycarbonyl (Cbz)-protected 2-aminoalkanesulfonyl chlorides are useful building blocks for the synthesis of sulfonopeptides, which are receptor ligands and enzyme inhibitors, and are prepared by the coupling reaction of N-protected aminoalkanesulfonyl chlorides with amino acid or peptide esters. Various N-Cbz-protected 2-aminoalkanesulfonyl chlorides with functionalized side chains were synthesized through the radical addition of different xanthates to benzyl N-allylcarbamate and subsequent oxidative chlorination with tert-butyl hypochlorite under neutral conditions. A mechanism for the oxidative chlorination is proposed. This is a useful and convenient strategy for the synthesis of N-Cbz-protected 2-aminoalkanesulfonyl chlorides with diverse functionalized side-chains.
Abdellaoui, Hassane,Chen, Xingpeng,Xu, Jiaxi
p. 2250 - 2256
(2017/05/05)
One-pot synthesis of symmetric 1,7-dicarbonyl compounds via a tandem radical addition-elimination-addition reaction
A novel approach to synthesize symmetric 1,7-dicarbonyl compounds via a tandem radical addition-elimination-addition reaction of S-carbonylmethyl xanthates with allylmethylsulfone and its analogues has been developed. Radicals were produced from S-carbonylmethyl xanthates by adding dilauroyl peroxide and reacted with allylmethylsulfone or analogues to generate terminal olefins as intermediates. The excessive radicals reacted with the intermediate olefins immediately to give adducts of symmetric 1,7-dicarbonyl compounds. This is an efficient method to synthesize 1,7-dicarbonyl compounds under mild conditions. The Royal Society of Chemistry 2013.
Huang, Zhongyan,Xu, Jiaxi
p. 15114 - 15120
(2013/09/02)
Expeditious synthesis of 1-substituted taurines with diverse functionalized side-chains
A radical addition reaction and subsequent performic acid oxidation were used for the synthesis of 1-substituted taurines with diverse functionalized side-chains from N-allylphthalimide and various xanthates. The current approach shows high yields and short synthetic route and reaction time. Moreover, the current method is a convenient and practical method for the synthesis of 1-substituted taurines with different functionalized side-chains.
Kakaei, Saeed,Chen, Ning,Xu, Jiaxi
supporting information
p. 302 - 309
(2013/01/15)
Free-radical carboalkynylation and carboalkenylation of olefins
Free-radical three-component carboalkynylation and -alkenylation of olefins have been developed. These involve the addition, across the double bond of an unactivated olefin, of a radical species α- to an electron-withdrawing group and an alkenyl or alkynyl moiety, derived from the corresponding sulfones.
The Invention of New Radical Chain Reactions. Part 9. Further Radical Chemistry of Thiohydroxamic Esters; Formation of Carbon-Carbon Bonds
Carbon radicals derived from the esters of several types of thiohydroxamic acids have been trapped in a number of different ways.Particular attention has been paid to carbon-carbon bond formation by addition to suitably activated ethylenic linkages.Carboxylic acids can be conveniently converted into homo- and bishomo-acids by free radical chemistry based on thiohydroxamic esters.In a coda the tautomerism of the thiohydroxamic acids have been examined by physical methods.It is confirmed that the esters used are derivatives of the thione tautomer.
Barton, Derek H.R.,Crich, David,Kretzschmar, Gerhard
p. 39 - 54
(2007/10/02)
A NEW GENERAL SYNTHESIS OF 2-(N-MONO- AND N-DI-SUBSTITUTED AMINO)THIAZOLES
Although α-mercapto ketones react with cyanamides to give substituted 2-aminothiazoles the yields are satisfactory in only the simplest cases.However, a range of 2-aminothiazoles with substituents on the ring or the exo-nitrogen atom was obtained efficiently by the following one-pot procedure: a solution of an α-mercapto ketone anion was generated by treating an O-ethyl S-2-oxoethyl dithiocarbonate with piperidine at 20 deg C, a cyanamide was added, and the solution was heated for 3-6 h.
Brown, Michael D.,Gillon, David W.,Meakins, G. Denis,Whitham, Gordon H.
p. 1623 - 1626
(2007/10/02)
RADICAL CHEMISTRY OF THIOHYDROXAMIC ACID ESTERS
Thiohydroxamic esters in general decompose smoothly by a radical chain reaction to give carbon radicals which can be quenched in a synthetically useful manner.
Barton, Derek H. R.,Kretzschmar, Gerhard
p. 5889 - 5892
(2007/10/02)
More Articles about upstream products of 49762-80-3