Ring-Opening Selenation of Cyclopropanol for the Selective Synthesis of ß-Hydroxy-Substituted Selenylated Ketones.

Ring opening of cycloalkanols has been employed as a commonly used strategy to prepare diverse distal functionalized ketones. However, most of these ketones obtained by this strategy belong to monofunctional ketones, while difunctional ketones with more potential application value have been rarely reported. Herein, we first reported a mild I2-promoted ring-opening selenation of cyclopropanol to synthesize various distal difunctional ketones. In the reaction, hydroxyl (-OH) derived from water and RSe+ from diselenide can be introduced into the α- and ß-positions, respectively, delivering ß-hydroxy selenylated ketones in good to excellent yields.

Organocatalytic direct asymmetric crossed-aldol reactions of acetaldehyde in aqueous media.

A new type of diarylprolinol-based catalyst, which contains a dioctylamino group in the presence of a newly developed ionic liquid supported (ILS) benzoic acid as cocatalyst, is shown to be an effective catalytic system for the asymmetric direct crossed-aldol reaction of acetaldehyde in aqueous media using brine. For the reactions studied, the catalyst loading could be reduced to 5 mol %; high yields (up to 97%) and high enantioselectivities (up to 92% ee) were also achieved for a wide variety of aromatic aldehyde.

Asymmetric Michael reactions catalyzed by a highly efficient and recyclable quaternary ammonium ionic liquid-supported organocatalyst in aqueous media.

A novel ionic liquid-support organocatalyst, which contains the quaternary ammonium ion moiety, was recently developed and successfully applied to the asymmetric Michael reaction in the presence of a newly developed ionic liquid-supported (ILS) benzoic acid as co-catalyst. For the reactions studied, in which various aldehydes and nitroolefins were examined, excellent diastereo- and enantioselectivities were obtained with low catalyst loading. Also, the catalyst could be recycled for ten times without significant loss of enantioselectivity.

Highly enantioselective and recyclable organocatalytic Michael addition of malonates to α,ß-unsaturated aldehydes in aqueous media.

A new type of pyrrolidine-based organocatalyst, which was developed earlier in our lab, has been found to be very effective for the Michael addition reaction in aqueous solvents involving a wide range of α,ß-unsaturated aldehydes and malonate derivatives. For the reactions studied, good to excellent yields (73%-96%) and high to excellent enantioselectivities (up to 97%) were obtained using this catalyst. In addition, the catalyst could be recycled up to four times with gradual reductions in yields and enantioselectivity observed after the second cycle.

Bimetallic Metal-Organic Coordination Polymers Facilitated the Selective C-F Cleavage of Polyfluoroarenes.

Selective C-F bond cleavage of polyfluoroarenes has attracted tremendous interest due to its promising applications in introducing fluorinated building blocks into organic molecules. However, it remains a challenge to achieve highly site-selective C-F bond cleavage because of the intrinsic inertness of the C-F bond and the difficulty in distinguishing specific C-F bonds on the aromatic ring. Herein we report an efficient nucleophilic aromatic substitution (SNAr) reaction of polyfluoroarenes with Grignard reagents that employs MnFe-based bimetallic metal-organic coordination polymers (MOCPs) as recyclable and reusable heterogeneous catalysts. Significantly, in this reaction, the prepared MOCP (Mn-Fe) catalyst exhibited excellent activity in selective C-F bond cleavage and afforded a series of functionalized polyfluoroarenes in moderate to excellent yields (up to 96%). This work highlights the potential of MOCP catalysts to serve as a tunable platform in Lewis acid catalysis.

Electrochemical Selenium-Catalyzed N,O-Difunctionalization of Ynamides: Access to Polysubstituted Oxazoles.

A green and efficient approach for the difunctionalization of ynamides by merging the electrochemical and organoselenium-catalyzed processes is described. This strategy features mild reaction conditions, broad functional group tolerance and high atom-economy, and requires no external chemical oxidant. Hence, we provide a sustainable alternative for the synthesis of polysubstituted oxazoles.

Diarylprolinol silyl ether salts as new, efficient, water-soluble, and recyclable organocatalysts for the asymmetric Michael addition on water.

A novel strategy for the catalytic asymmetric Michael addition of aldehydes to nitroolefins on water has been developed and provided the Michael adducts in excellent diastereo- and enantioselectivities. A notable feature of these organocatalysts is that they can be recycled for more than six times without a significant loss of catalytic activity and stereochemical control. In addition, the synthetic procedure presented is simple, practical, and environmentally benign.

Ionic-liquid-supported (ILS) catalysts for asymmetric organic synthesis.

The asymmetric synthesis of compounds that contain new C-C and C-O bonds remains one of the most important types of synthesis in organic chemistry. Over the years, many different types of catalysts have been designed and used effectively to carry out such transformations. Ionic-liquid-supported (ILS) catalysts represent a new and very effective class of catalysts that are used to facilitate the asymmetric synthesis of such compounds. There are many advantages to using ILS catalysts; they are nontoxic, environmentally benign, and, most important, recyclable. An overview of the design, synthesis, mode of action, and effectiveness of this class of catalysts is reported.

Design and synthesis of bistereogenic chiral ionic liquids and their use as solvents for asymmetric Baylis-Hillman reactions.

Three novel chiral ionic liquids (CILs) containing two chiral centers in the side chain bonded to the 2-position of the imidazolium cation and different anions have been synthesized, characterized and used as chiral solvents for asymmetric Baylis-Hillman (BH) reactions; good yields and fair enantioselectivities were obtained.

Study on the noncoincidence effect phenomenon using matrix isolated Raman spectra and the proposed structural organization model of acetone in condense phase.

The isotropic and anisotropic Raman spectra of acetone and deuterated acetone isolated in an argon matrix have been recorded for the understanding of noncoincidence effect (NCE) phenomenon. According to the matrix isolated Raman spectra and DFT calculations, we proposed aggregated model for the explanations of the acetone C=O vibration NCE phenomenon and its concentration effect. The experimental data were in consistence with the DFT calculations performed at the B3LYP-D3/6-311 G (d,p) levels based on the proposed model. The experimental identification of the monomer, dimer and trimer are reported here, and the dynamic of the transformation from monomer to aggregated structure can be easily controlled by tuning annealing temperature.

Corrigendum: Study on the noncoincidence effect phenomenon using matrix isolated Raman spectra and the proposed structural organization model of acetone in condense phase.

This corrects the article DOI: 10.1038/srep43835.

Unexpected dramatic substituent effect for tuning the selectivity in the double ring-closing metathesis reaction of N-containing tetraenes. An efficient synthesis of bicyclic izidine alkaloid skeletons.

[reaction: see text] A double ring-closing metathesis reaction for the efficient construction of the fused bicyclic izidine alkaloid skeleton was developed. In this reaction, high selectivity was realized by tuning of electronic and steric effects of substituents in the N-containing tetraenes. It was observed that the reactivity of electron-rich carbon-carbon double bonds is higher than that of electron-deficient ones. A brief mechanistic study is also discussed.

Di(methylimidazole)prolinol silyl ether catalyzed highly Michael addition of aldehydes to nitroolefins in water.

A new pyrrolidine-based organocatalyst for asymmetric reactions has been developed and shown to be a very effective catalyst for the Michael reaction involving various nitroolefins and aldehydes in water. This design is based on the introduction of a hydrophilic group into the pyrrolidine side chain. This catalyst, di(methylimidazole)prolinol silyl ether in combination with sodium bicarbonate as additive effectively catalyzed the Michael addition of aldehydes to nitroolefins in water as solvent in high yields and excellent enantioselectivities.

Ionic liquid-supported (ILS) (S)-pyrrolidine sulfonamide, a recyclable organocatalyst for the highly enantioselective Michael addition to nitroolefins.

A new class of ionic liquid supported (ILS) (S)-pyrrolidine sulfonamide organocatalyst has been developed and shown to be a very effective catalyst for the asymmetric Michael addition reactions of ketones and aldehyde to nitroolefins with high enantio- and diastereoselectivities. This ILS organocatalyst is also easily recycled and could be reused at least five times without significant loss of its ability to affect the outcome of the asymmetric reactions.

Design and synthesis of pyridinium chiral ionic liquids tethered to a urea functionality.

Nine chiral room-temperature ionic liquids (RTILs), which contain a chiral moiety and a urea functionality bonded to a pyridinium ring, have been designed and synthesized. The synthesis of these ionic liquids is concise and practical due to the commercial availability of the starting materials. These novel RTILs were readily prepared from 2-(aminomethyl)pyridine and amino acid ester derived isocyanates. We envision that these new chiral RTILs can serve as effective reaction media as well as chiral catalysts for asymmetric reactions, which are presently being investigated in our laboratory.

Design and synthesis of C-2 substituted chiral imidazolium ionic liquids from amino acid derivatives.

[reaction: see text] A series of novel chiral ionic liquids (CILs) has been synthesized and fully characterized. The reaction of 1-methyl-2-imidazolecarboxaldehyde and chiral amino alcohols followed by reduction is key to the design of these new CILs. This is the first time that CILs have been synthesized by introducing chiral scaffolds on the C-2 position of the imidazolium cation of ILs. The simple and straightforward procedure resulted in CILs as colorless oils at room temperature in good yields.

Intramolecular triple heck reaction. An efficient entry to fused tetracycles with a benzene core.

Twelve examples of 1,3,5-tribromo-2,4,6-trienylbenzenes were easily synthesized by alkylation, etherification, and amination methods. Under conditions A and B, a series of tetracycles with a benzene core, i.e., fused 5,6,6-, 6,6,6-, and 6,6,7-tetracyclic compounds, were prepared efficiently via this intramolecular triple Heck reaction protocol.

Double ring-closing metathesis reaction of nitrogen-containing tetraenes: efficient construction of bicyclic alkaloid skeletons and synthetic application to four stereoisomers of lupinine and their derivatives.

The double ring-closing metathesis reaction of nitrogen-containing tetraenes was studied. The selectivity of the fused/dumbbell-type products can be controlled by the electronic/steric effects of the substituents attached to the C[double bond]C bonds and the s-cis/s-trans conformational ratios of the substrates. This methodology has also been successfully applied to the enantioselective synthesis of four stereoisomers of lupinine and their derivatives.

Highly selective synthesis of bicyclic quinolizidine alkaloids and their analogues via double RCM reaction of N-alkynyl-N-(1,omega)-alkadienyl acrylamides.

The double ring-closing metathesis reaction of N-alkynyl-N-(1,omega)-alkadienyl acrylamides 1 using first- or second-generation Grubbs' catalyst afforded, in a highly selectively manner, the fused bicyclic quinolizidine alkaloid derivatives and their analogues bearing a 1,3-diene moiety, which may further undergo a Diels-Alder reaction with a dienophile to afford N-containing polycyclic compounds. The excellent selectivity of fused/dumbbell-mode cyclization has been realized by the higher reactivity of the electron-rich C=C bond or carbon-carbon triple bond combined with the lower reactivity of the electron-deficient C=C bond toward metallocarbenes and the thermodynamically more stable nature of fused bicyclic compounds 3 vs dumbbell-type bicyclic compounds 4.