New star shaped block copolymers were synthesized according to a core first strategy, with a hydrophobic polytetrahydrofuran (PTHF) central block and a poly(2-methyl-2-oxazoline) (PMeOx) external block. First, the cationic polymerization of THF was initiated from a tetrafunctional triflate ester...
A series of brush copolymers, poly[(2-methyl-2-oxazoline)-random-4-vinylpyridine] (PMOXA-r-4VP), with a variety of compositions was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of the poly(2-methyl-2-oxazoline) methacrylate macromonomer (PMOXA-MA) and 4-v...
In this work, poly[(2-methyl-2-oxazoline)-random-glycidyl methacrylate] (PMOXA-r-GMA) and poly(4-vinyl pyridine)-block-poly(glycidyl methacrylate) (P4VP-b-PGMA) were synthesized by cationic ring opening polymerization (CROP) of 2-methyl-2-oxazoline (MOXA) and reversible addition-fragmentation ch...
The regiochemical outcome of the ring opening of 1,2-epoxides through chelation processes assisted by metal ions, was verified in the oxirane systems derived from cyclopentene bearing a polar functionality (CH2OBn or COOMe) in a homoallylic relationship to the oxirane ring. The cis/trans diaster...
The known methyl 2-methyl-3-oxo-1-cyclopentene carboxylate was acetoxylated by reaction with N-bromosuccinimide and subsequent treatment with silver acetate. Methanolysis of this acetoxy compound yielded methyl 5-hydroxy-2-methyl-3-oxo-1-cyclopentene carboxylate. Reaction of silver 3,5-dinitrobe...
2-Halobenzyl 1-alkynyl sulfides undergo an unprecedented dihydrothiophene formation when treated with 2 equiv. of KOtBu in CH3CN. The reaction, believed to proceed via a 5-endo-dig cyclization, is sluggish or non-existent in the absence of the halogen.
Heating the onion oil component bis(1-propenyl) disulfide gives cis/-and trans-2-mercapto-3,4-dimethyl-2,3-dihydrothiophene which can lose H2S upon further heating giving 3,4-dimethylthiophene. A dithio-Claisen rearrangement is proposed for the key step.
3-Carboalkoxy-2,3-dihydrothiophenes, available by Birch reduction of thiophene-3-carboxylic acid or more efficiently by deconjugation of 2,5-dihydrothiophene-3-carboxylic acid by reaction with ethyl chloroformate and triethylamine, undergo cycloaddition reactions with dichloroketene leading to 4...
A facile and direct synthetic method was developed for the construction of fully substituted dihydrothiophenes, which via a copper-catalyzed Michael addition/intramolecular cyclization/protonation cascade reaction of readily available thioamides with enynones under air atmosphere. This approach ...
Oxidation of 4-substituted 2,2-bis(trifluoromethyl)thietanes by m-chloroperoxybenzoic acid results in selective formation of the corresponding S-oxides in 65–86% yield. Oxidation of 4-C2H5S-2,2-bis(trifluoromethyl)thietane under mild conditions led to selective formation of 4-C2H5SO2-2,2-bis(tr...
The hitherto unknown 2,3-dimethylene-2,3-dihydrothiophene (the thiophene analogue of ortho-xylylene) and a substituted derivative have been prepared in solution and trapped as Diels-Alder adducts in good to excellent yields.
Comparative studies of the hydrodesulfurization (HDS) of thiophene, 2,3-dihydrothiophene, 2,5-dihydrothiophene and tetrahydrothiophene were performed using Moγ-Al2O3 and Reγ-Al2O3 catalysts. Reaction pathways for interconversion of the organosulfur compounds were shown to exist. Both dihydroth...
2,3-Dimethylene-2,3-dihydrothiophene (the analogue of o-xylylene) is generated in situ from 3-(trimethylanunoniuinmethyl)-2-(trimethylsilylmethyl) thiophene iodide (7) by a fluoride induced 1,4-elimination process, and is identified by several [4+2] cycloadducts obtained in high yields.
An efficient synthetic approach to variously substituted 2,3-dihydrothiophenes has been developed. The reaction proceeded by copper-catalyzed tandem S-alkylation and S-alkenylation of sodium sulfide with 1,4-diiodobut-1-enes to afford the corresponding 2,3-dihydrothiophene derivatives in high yi...
Various spirooxindoles bearing 2,3-(or 2,5-)dihydrothiophene-2-thione moiety have been synthesized via [3+2] annulation reaction of carbon disulfide and the nitrogen ylides derived from Morita-Baylis-Hillman carbonates of isatins. 2,3-Dihydro- and 2,5-dihydrothiophene-2-thione moieties were form...
A new [18F] labeled amino acid anti-1-amino-2-[18F]fluoro-cyclobutyl-1-carboxylic acid 9 (anti-2-[18F]FACBC) was synthesized in 30% decay-corrected yield with high radiochemical purity over 99%. The cyclic sulfamidate precursor was very stable and highly reactive towards nucleophilic radiofluori...
(E)-Alkenylsilanes were synthesized with high stereoselectivity by the diastereoselective addition of the dimethylphenylsilyllithium to the trans-2-phenylthiocyclobutyl ketones and the Lewis acid-promoted stereospecific ring opening reactions of the resulting cyclobutanemethanol derivatives. (E)...
A novel class of 1′-cyclobutyl-6-(4-piperidyloxy)spiro[benzopyran-2,4′-piperidine] derivatives with low nanomolar affinity for the human and rat histamine-3 receptors (H3Rs) are described. The spirobenzopyran piperidine ether analogs demonstrated excellent H3R affinity and selectivity against ...
The two enantiomers of the title dehydroamino acids (DHAAs) have been synthesized through respective Wadsworth–Emmons condensations of a suitable phosphonate with enantiomeric cyclobutyl aldehydes. These compounds, in turn, were prepared by selective manipulation of the functional groups starti...
Differently substituted cyclopropylcarbinols underwent ring cleavage with easily accessible cyanuric chloride–N,N-dimethylformamide adduct to produce homoallylic chlorides or dienes depending on the nature and location of the substituents. A mechanistic explanation of the aforesaid observations...
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