Xiao-Qi Yu

Enantioselective Gel Collapsing: A New Means of Visual Chiral Sensing

An optically active BINOL-terpyridine based Cu(II) complex (R)-2 was prepared. Sonication of (R)-2 in CHCl(3) led to the formation of a stable gel. The interaction of this gel with chiral amino alcohols was studied. It was found that (S)-phenylglycinol (0.10 equiv) could break the gel network of (R)-2 (3.75% w/v, g/mL) in CHCl(3) to cause gel collapsing but (R)-phenylglycinol (0.10 equiv) could not. Similar enantioselective gel collapsing was also observed with (R)- and (S)-1-amino-2-propanol. This study demonstrates that chiral molecular gels are potentially useful for visual chiral discrimination. Complex (R)-2 in solution also exhibited significant enantioselective fluorescent enhancement in the presence of a variety of amino alcohols.

Imidazolium-Functionalized BINOL as a Multifunctional Receptor for Chromogenic and Chiral Anion Recognition

A novel imidazolium-functionalized BINOL fluorescent receptor R-1 was developed as a multifunctional receptor for both chromogenic and chiral anion recognition. The different fluorescent responses and color changes of R-1 could be applied to the detection of fluoride and acetate ions by the naked eye. Furthermore, the chiral recognition of the two enantiomers of alpha-amino carboxylates was also studied, and R-1 displayed a remarkable binding ability for the t-Boc alanine anion with an interesting enantioselectivity (K(L)/K(D) = 4.5).

Biocatalytic promiscuity: the first lipase-catalysed asymmetric aldol reaction

It was first observed that PPL, lipase from porcine pancreas, and several other lipases have a promiscuous ability to catalyse asymmetric aldol reactions between acetones and aldehydes in the presence of water.

Lipase-catalysed direct Mannich reaction in water: utilization of biocatalytic promiscuity for C–C bond formation in a “one-pot” synthesis

A novel lipase-catalysed direct Mannich reaction has been developed under aqueous conditions in a “one-pot” strategy. Interestingly, these promiscuous reactions can be greatly promoted by water and generally require aromatic aldehydes.

A simple copper salt catalysed the coupling of imidazole with arylboronic acids in protic solventDedicated to Professor Xie Ming-Gui on the occasion of his 65th birthday.

In the presence of a catalytic amount of a simple copper salt, the coupling of imidazole with arylboronic acids was performed in methanol to give corresponding N-arylimidazoles in almost quantitative yields; this coupling reaction could also be performed in aqueous solutions to give N-arylimidazoles in excellent yields.

A real-time colorimetric and ratiometric fluorescent probe for sulfite.

A real-time colorimetric and ratiometric fluorescent probe based on modulating the intramolecular charge transfer (ICT) of the coumarin platform for selective detection of sulfite is presented. This reaction based probe utilized the Michael addition to the dicyano-vinyl group with the detection limit of 5.8 × 10(-5) M. The probe displayed a high selectivity for sulfite over other anions and reactive sulfur especially for biothiols including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), with about 100 nm blue shift and more than 230 times intensity ratios change of the emission spectrum. Meanwhile, it could be easily observed that the probe for sulfite changes from red to pale yellow by the naked eye, and from red to blue under UV lamp immediately after the sulfite is added. To the best of our knowledge, it is the fastest response probe for sulfite ever reported, which could give a colorimetric and ratiometric fluorescent response instantly.

Iron-catalyzed direct amination of azoles using formamides or amines as nitrogen sources in air

A new iron-catalyzed, direct C-H amination of azoles at C2 has been developed by using formamides or amines as nitrogen sources. Imidazole is the only additive in the catalyst system and oxygen in air is employed during the transformation process.

Direct arylation of arene and N-heteroarenes with diaryliodonium salts without the use of transition metal catalyst.

A novel and simple transition metal-free direct arylation of arene and N-heteroarenes with diaryliodonium salts has been developed. This cross-coupling reaction is promoted only by base and gives the desired products in moderate to good yields.

Iron-mediated direct Suzuki-Miyaura reaction: a new method for the ortho-arylation of pyrrole and pyridine.

The first example of an iron-mediated direct Suzuki-Miyaura reaction between N-heterocyclic compounds and arylboronic acids is described, and both electron-rich and electron-deficient heteroarenes can be successfully used for the coupling reaction.

Copper-catalyzed nitrogen loss of sulfonylhydrazones: a reductive strategy for the synthesis of sulfones from carbonyl compounds.

An efficient method for the synthesis of sulfones via nitrogen loss of sulfonyl hydrazones is described. The reaction was performed in the presence of simple copper salt and base by utilization of sulfonyl hydrazones, which were easily prepared from carbonyl compounds. A wide variety of aryl and alkyl sulfones were obtained in moderate to good yields.