Facile synthesis of C-phosphanylformamidines via a carbene pathway

A direct synthetic approach to C-phosphanyl-N,N-dialkyl-N′-aryl(alkyl)-formamidines was developed. It was shown that phosphorylation of the formamidines proceeds at the nitrogen atom affording N-phosphanylformamidinium salts. Upon deprotonation, these salts gave C-phosphanylformamidines via formation of carbenes followed by a 1,2-phosphorus shift.     

Facile synthesis of dihaloheterocycles via electrophilic iodocyclization

An efficient and facile electrophilic iodocyclization for the synthesis of various O-, N-, and S-containing dihaloheterocycles has been developed. A wide range of the substituted propargyl alcohols having -OH, -NTs, and -SAc functional groups reacted with molecular iodine or bromoiodine at ambient temperature to produce the corresponding dihalogenated O-, N-, and S-containing five- and six-membered heterocycles in good to high yields; Under optimized solvent conditions, the reactions of various substituted but-2-yn-1-ones bearing -OH, -NTs, and -SAc functional groups at C4-position, with iodine or bromoiodine at ambient temperature afforded the corresponding 3,4-diiodo- and 3-bromo-4-iodo-substituted furans, pyrroles, and thiophenes in good to high yields. Further transformation of the resulting iodine- or bromine-containing products to polyaromatics potentially of useful as organo-material intermediates has been investigated.     

Facile synthesis of novel monodisperse linear 3,9-linked oligocarbazoles

Novel monodisperse linear 3,9-linked oligocarbazoles (OCAs) were prepared stepwise using Ullmann coupling reaction in seal-tubes. The resulting OCAs were soluble in common organic solvents. The UV-vis spectra of OCAs exhibited small red shift and their intensities increased linearly with the increase of the carbazole moieties, suggesting that no intramolecular π-interactions appeared at ?8-mer. All the OCAs gave strong fluorescence and it was found that the conjugated degree of linear OCAs would be saturated when the number of carbazole units reaches four.     

Facile synthesis of amine-terminated aromatic polyamide dendrimers via a divergent method

[structure: see text]. A novel, rapid, inexpensive, and highly efficient divergent approach for the synthesis of a 32-amine-terminated G4 polyamide dendrimer has been developed. Each generation dendrimer was successfully obtained by the condensation of the preceding generation dendrimer with the building block and the deprotection with hydrazine in one pot. All the dendrimers were easily purified by precipitation in alkaline water, and the purity was confirmed by NMR, MALDI-TOF mass spectra, and elemental analysis.     

Facile one-pot synthesis of PEG-derived carbon dots with enhanced luminescence via L-cysteine-assisted S,N-doping

Carbon nanodots (C-dots) are promising photoluminescent nanomaterials for biomedical applications. Among them, PEG-derived C-dots demonstrate exceptional photoluminescence and passivation properties, making them particularly attractive for use in the biomedical field. In this article, we present the synthesis of photoluminescent S,N-doped PEG-derived carbon dots that are stable at ambient temperature and can be produced using an easy hydrothermal technique. To synthesize the carbon dots, the non-hazardous polymer polyethylene glycol (PEG) was used as the sole precursor rather than any other potentially hazardous compounds. The absence of L-cysteine in the reaction mixture resulted in carbon dots with no significant absorbance in the visible region but exhibited photoluminescence properties with a maximum excitation and emission at 343 and 452 nm, respectively. However, the addition of L-cysteine resulted in a visible absorbance and a red shift in both the maximum excitation and emission, at around 435 and 503 nm, respectively. The Fourier transform infrared spectroscopy (FTIR) analysis provided evidence for the presence of -SH, -SO₂, -NH₂, and CON-H bond stretching after the addition of L-cysteine, suggesting possible S,N-doping of the carbon dots, which likely caused the observed changes in photoluminescence properties. These findings contribute to the understanding of S,N-doping in carbon dots and highlight their potential applications in optoelectronics, sensing, and biomedical imaging.     

Facile synthesis of 3,4-dihalofurans via electrophilic iodocyclization

A facile, efficient, and general synthetic method for 3,4-dihalofurans has been developed via the electrophilic iodocyclization of various 4-hydroxy-2-but-2-yn-1-ones. The use of MeOH as a solvent is crucial for the efficient chemoselective synthesis of the corresponding 3,4-dihalofurans.     

Facile synthesis of 3,4-diiododihydrothiophenes via electrophilic iodocyclization

A facile, efficient, and general synthetic method for the construction of 3,4-diiododihydrothiophenes has been developed via the electrophilic iodocyclization of various S-hydroxy-2-butynyl ethanethioates. Application of the resulting iodine-containing products in organic transformations has been investigated.     

Facile synthesis of functionalised spiroethers via radical cyclisations

Alcohols bearing suitable chains for radical initiation are smoothly condensed with cyclic β-diketones to afford systems which undergo radical cyclisation to give various spiroether products.     

Facile peptide thioester synthesis via solution-phase tosylamide preparation

Preparation of peptide thioester is essential for native chemical ligation and block condensation. Our novel methodology involves conversion of the carboxylic acid of a peptide into a thioester using p-toluenesulfonyl isocyanate, followed by alkylation, then thiol substitution. Our methodology can also be used for the preparation of glycopeptide thioesters. Furthermore, it is possible to carry out the reaction as a sequential peptide chemical ligation.     

Facile synthesis of thiazoles via an intramolecular thia-Michael strategy

A mild and efficient method for the synthesis of substituted thiazoles is reported via one-pot N-desilylation, thioacylation/oxythioacylation/thiothioacylation followed by thia-Michael cycloisomerisation. This method has a general applicability to introduce various oxo and thio functionalities including aliphatic and aromatic moieties, especially at the C2-position of thiazoles.     

Facile synthesis of multifullerene-OPE hybrids via in situ ethynylation

[reaction: see text] A series of fullerene-terminated oligo(phenylene ethynylene)s (OPEs) (1a-d and 2) have been synthesized and further characterized by cyclic voltammetry (CV) and UV-vis spectroscopy. The key step in the syntheses is an effective one-pot reaction that allows the attachment of C(60) to multiple terminal alkynes.     

Synthesis and Controlled Polymerisation of a Novel Gramicidin S Analogue

Summary: The controlled polymerisation of a bulky, peptide‐based monomer was investigated. The cyclic β‐sheet forming decapeptide gramicidin S was modified with a methacrylate handle and subsequently polymerised via atom transfer radical polymerisation (ATRP), to yield a well‐defined gramicidin‐S‐containing polymer. The secondary structure of the peptide moiety was retained within the resulting polymer, as indicated by IR spectroscopy. This is the first example of the use of ATRP to create a synthetic polymer with a cyclic peptide as a side chain.

The gramicidin S based monomers synthesised here were then polymerised by ATRP.     

Facile synthesis of primary amides and ketoamides via a palladium-catalysed carbonylation-deprotection reaction sequence

Various primary amides and ketoamides have been obtained in good yields in a two-step reaction sequence. The first step involves the synthesis of aryl/alkenyl N-tert-butyl amides and aryl N-tert-butyl ketoamides from the corresponding iodides via palladium-catalysed carbonylation in the presence of t-BuNH₂ as the nucleophile. Carbonylation was followed by selective cleavage of the t-Bu group using TBDMSOTf as the reagent.     

Facile synthesis of beta-organotellurobutenolides via electrophilic tellurolactonization of alpha-allenoic acids

We report a convenient and highly efficient method for the synthesis of beta-organotellurobutenolides by the aryltellurenyl halides-induced electrophilic tellurolactonization of alpha-allenoic acids under mild conditions. The resulting beta-organotellurobutenolides can be utilized as precursors for versatile butenolide derivatives through a substitution reaction with organocuprate reagent or Pd/Cu(I)-catalyzed cross-coupling with terminal alkyne.     

Facile synthesis of sugar lactols via bromine-mediated oxidation of thioglycosides

Synthesis of a variety of sugar lactols (hemiacetals) has been accomplished in moderate to excellent yields by using bromine-mediated oxidation of thioglycosides. It was found that acetonitrile is the optimal solvent for this oxidation reaction. This approach involving bromine as oxidant is superior to that using N-bromosuccinimide (NBS) which produces byproduct succinimide often difficult to separate from the lactol products.     

Facile synthesis of N-substituted pyrroles via microwave-induced bismuth nitrate-catalyzed reaction

Simple synthesis of N-substituted pyrroles using microwave-induced bismuth nitrate-catalyzed reaction has been accomplished with an excellent yield. A plausible mechanism has been advanced. This reaction also provides a simple method to prepare diverse varieties of N-substituted pyrrole derivatives with less nucleophilic polyaromatic amines.     

Facile access to 3-cyano-4-azaindoles via a modified Madelung indole synthesis

An unprecedented methodology for the facile synthesis of 2-substituted 3-cyano-4-azaindoles using modified Madelung synthesis is described. The methodology relies on acid and amine coupling under very mild conditions.