AIEgen based light-up probes for live cell imaging

Fluorescent light-up probes comprising a tetraphenylethene unit with aggregation-induced emission (AIE) characteristics and a water-soluble peptide have been designed and synthesized which provide cell membrane and nuclear permeability to live cells. This strategy has offered new opportunities for the development of probes with light-up ability and good signal-to-noise ratio. The selectivity or targeting specificity is determined by the peptide sequence, i.e. a nuclear localization signal that leads to nucleus imaging and a cell biomarker targeting peptide that offers specific light-up imaging of HT-29 cells.     

A facile electrochemical method for synthesis of new benzofuran derivatives

Electrooxidation of 3-substituted catechols has been studied in the presence of dimedone in aqueous solution, using cyclic voltammetry and controlled-potential coulometry. The results indicate that the quinones derived from catechols participate in Michael addition reactions with dimedone to form the corresponding benzofuran derivatives (6a-c). We propose a mechanism for the electrode process. The efficient electrochemical synthesis of 6a-c has been performed at carbon rod electrodes in an undivided cell using a constant current.     

A facile method for fluoroalkylation of aniline and its derivatives

In the presence of tetrakis(triphenylphosphine)nickel, fluoroalkylation reactions of aniline and its derivatives occur under mild conditions, giving good yields of the corresponding o- and p-fluoroalkylaniline. The reaction shows regioselectivity. The hydrolytic behaviors of the products are also described.     

A facile synthesis of functionally complex isoxazole derivatives

Metalation of 2(4′-Isoxazolyl)-Δ²-oxazolines takes place initially and selectively on the C-5′-alkyl group. Subsequent metalation also proceeds at this position. Selective deprotection of the oxazoline was accomplished without disturbing the isoxazole ring.     

A facile synthesis of some substituted furopyrimidine derivatives

Some substituted furopyrimidine derivatives are prepared in high yield in 4 steps, starting from the reaction of furoin (1,2‐di(furan‐2‐yl)‐2‐hydroxyethanone) and malonitrile.     

A facile synthesis of pyrazole-5-sulfonamide derivatives

The reaction of the 5-unsubstituted pyrazoles 2a-k with lithium diisopropylamide or n-butyllithium gave intermediary 5-lithiopyrazoles, whose reaction with sulfur dioxide afforded the lithium pyrazole-5-sulfinates 3a-k . Subsequent reaction of 3a-k with N-chlorosuccinimide followed by ammonolysis provided the pyrazole-5-sulfonamides 5a-k .     

A facile and efficient synthesis of bisazine derivatives

1,4‐Phenylenediamine was condensed with acetylacetone to give 4,4′‐[1,4‐phenylenedi‐(nitrilo)]‐dipenten‐2‐ol 1 . Compound 1 reacted with different organic reagent to give bisazine derivatives. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:293–299, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20017     

A facile four component protocol for the synthesis of dihydropyridine derivatives

An efficient one pot synthesis of dihydropyridine derivatives employing the transient zwitterions generated from aniline and allenoates is described.     

A facile aminocyclization for the synthesis of pyrrolidine and piperidine derivatives

Bromination of an isolated double bond followed by aminocyclization furnishes a highly stereoselective protocol for the intramolecular formation of pyrrolidine and piperidine ring containing subunits that are presented in numerous biologically active natural products.     

A facile preparation of trisubstituted amino-furan and -thiophene derivatives

β-Alkylation of amino-furan and -thiophene heterocycles is described through metal-, acid- and base-free carbon-carbon bond formation. The ability of both heterocycles to undergo selective β-alkylation is compared by mean of experimental and theoretical data. The presence of chiral amine substituents induced the diastereoselective generation of the newly formed additional stereocenter.     

A facile tandem carbene-ylide route to 2-fluoropyrrole derivatives

2-Fluoropyrroles were synthesised via 1,3-dipolar cycloaddition of iminiodifluoromethanides derived from corresponding imines and difluorocarbene to dimethyl acetylenedicarboxylate.     

A facile synthesis of benzo[b]thiophene derivatives

Lithiation of S-(2-methylphenyl) N,N,N',N'-tetramethylphosphorodiamidothioate with sec-BuLi at -105° gave the corresponding benzylic anion which was acylated with various aromatic esters to give various deoxybenzoin derivatives in moderate to high yields. Acidic treatment of these products in refluxing formic acid gave 2-arylbenzo[b]thiophene derivatives. 2-Methylbenzo[b]thiophene and benzo[b]thiophen-2(3H)-one were also prepared using the similar procedure.     

A facile synthesis of novel 1,4-benzoxazepin-2-one derivatives

An efficient and simple synthesis of 1,4-benzoxazepin-2-one derivatives has been achieved via the reaction of isoquinoline, activated acetylenes, and 1-(6-hydroxy-2-isopropenyl-1-benzofuran-yl)-1-ethanone in water without using any catalyst. This one-pot reaction occurs in high yields under mild conditions.     

A facile synthesis of 2-deoxy-2,3-didehydroneuraminic acid derivatives

The 2-thio- or 2-selenoglycosides of N-acetylneuraminic acid methyl ester were transformed by successive treatment with dimethyl(methylthio)sulfonium triflate (DMTST) and 1,8-diazabicyclo[5.4.0]-7-undecene (DBU) to give the corresponding methyl 2-deoxy-2,3-didehydroneuraminates in excellent yields. Their acids and their analogues are sialidase inhibitors of pharmaceutical interest.     

A facile synthesis of imino-protected cyclic guanidine derivatives from diamines

A convenient one-step synthesis of five-membered or six-membered imino-protected cyclic guanidine via an intramolecular ring-closure reaction of alkyl diamine(2a-2g) with 1,3-diamino-protected methylisothiourea(1a and 1b) was established and investigated.Amino guanidine such as 3-(2-aminoethyl)-1,2-dibenzyloxycarbonylguanidine(4a) has been proved to be the intermediate of the reaction via utilizing mono-protected diamine as starting material.The intramolecular ring closure of 4a results in 2-benzyloxycarbonyliminoimidazolidine(3a).This new one-step synthesis has advantages of simple condition,easy workup procedure and reasonable yield.     

A facile synthesis of bisquinoline derivatives via the Williamson reaction

A series of new bisquinoline systems, ethyl 2-((quinolin-8-yloxy)methyl)quinoline-3-carboxylate derivatives (3a–i), were synthesized by Williamson reaction of ethyl 2-(halogenmethyl)quinoline-3-carboxylates (4a–c) with 8-hydroxyquinolines (5a–c) in CH₃CN as solvent and in the presence of K₂CO₃ as base. Characterization of these bisquinoline compounds was primarily achieved by use of spectral data and X-ray crystallography. This procedure enables easy access to bisquinoline compounds in a short reaction time and the products are obtained in high yields.     

A practical and facile synthesis of azetidine derivatives for oral carbapenem, L-084

An orally active carbapenem L-084, which exhibits high bioavailability in humans, has a 1-(1,3-thiazolin-2-yl)azetidin-3-ylthio moiety at the C-2 position of the 1beta-methylcarbapenem skeleton. We established a practical and cost-effective synthesis of 3-mercapto-1-(1,3-thiazolin-2-yl)azetidine (1) for further scale-up production of L-084. This synthesis method entails an industry-oriented reaction of azetidine ring-closure to yield N-benzyl-3-hydroxyazetidine (16), which is eventually converted to 1 via key intermediates, Bunte salts 19 and 20.