Trichloroisocyanuric acid: A convenient oxidation reagent for phase-transfer catalytic epoxidation of enones under non-aqueous conditions

Trichloroisocyanuric acid (TCCA) is a cheap, safe and readily available alternative to the commonly used hydrogen peroxide and hypochlorite for the phase-transfer catalytic epoxidation of alpha,beta-enones under non-aqueous conditions. A variety of chalcone derivatives give the corresponding epoxides with quantitative conversion and satisfactory yields in just a few hours under mild conditions. An asymmetric variant of the epoxidation can be carried out in the presence of chiral N-anthracenylmethylcinchonidine bromide catalyst giving 73-93% ees and 76-94% yields.

Highly enantioselective conjugate addition of diethylzinc to acyclic enones with fine-tunable phosphite-pyridine ligands

A new series of fine-tunable phosphite-pyridine (P,N) ligands derived from (S)-2-amino-T-hydroxy-6,6'-dimethyl-1,1'-biphenyl and (S)-2-amino-2'-hydroxy-4,4',6,6'-tetramethyl-1,1'-biphenyl was employed in Cu(I)-catalyzed conjugate addition of diethylzinc to acyclic enones. Excellent enantioselectivities (up to 98% ee) and highly catalytic activities were achieved for a variety of acyclic enones.

Application of a New Cyclic Guanidinium Ionic Liquid on Dye-Sensitized Solar Cells (DSCs)

A new cyclic guanidinium ionic liquid OGI (1,3-dimethyl-2-N ''-methyl-N ''-octylimidazoguanidinium iodide) has been used as a quasi-solid-state electrolyte for dye-sensitized solar cells (DSCs), and 6.38% conversion efficiency was achieved at AM 1.5 simulated sunlight (9.81 mW cm(-2)). Further gelation with SiO2 nanoparticles afforded the solid-state electrolyte, which presented overall conversion efficiency of 5.85%. The diffusion properties of these OGI-based electrolytes were investigated. In the meantime, the optimal structure and ion-pairing interaction in OGI have been proposed by density functional theoretical calculation (DFT) at the B3LYP/6-21G(d,p) level.

Why [6,6]- and 1,2-Benzal-3-N-4-O-Cyclic Phenylimidate C-60 Undergo Electrochemically Induced Retro-Addition Reactions while 1,4-Dibenzyl-2,3-Cyclic Phenylimidate C-60 Does Not? C-H center dot center dot center dot X (X = N, O) Intramolecular Interactions in Organofullerenes

The electrochemical properties of a series of structurally related fullerooxazoles, [6,6] cyclic phenylimidate C-60 (1), 1,2-benzal-3-N-4-O-cyclic phenylimidate C-60 (2), and 1,4-dibenzyl-2,3-cyclic phenylimidate C-60 (3), are described, and the spectroscopic characterizations of their anionic species are reported. The results show that compounds I and 2 undergo retro-cycloaddition reactions that lead to the formation of C-60 and C61HPh, respectively, upon two-electron-transfer reduction. However, compound 3 demonstrates much more electrochemical stability as no retro-cycloaddition reaction occurs under similar conditions. Natural bond orbital (NBO) calculations on charge distribution show there is no significant difference among the dianions of 1, 2, and 3, indicating that the electrochemical stability of 3 is unlikely to be caused by the charge distribution difference of the dianions of three compounds. Examination on the crystal structure of compound 3 reveals close contacts of the C-H group with the heteroatoms (N and O) of cyclic phenylimidate, suggesting the existence of C-H center dot center dot center dot X (X = N, O) intramolecular hydrogen bonding among the addends, which is further confirmed by NBO analysis.

An ionic liquid based on a cyclic guanidinium cation is an efficient medium for the selective oxidation of benzyl alcohols

A novel room temperature ionic liquid (RTIL) has been prepared containing a cyclic hexaalkylguanidinium cation. The selective oxidation of a series of substituted benzyl alcohols has been carried out in it, with sodium hypochlorite as the oxidant. The RTIL acts as both phase transfer catalyst (PTC) and solvent. The ionic liquid could be recycled after extraction of the benzaldehyde product with ether.

Ionic liquid solvent based on cyclic guanidinium cation for nucleophilic displacement reactions

The nucleophilic displacement reaction of n-bromooctane and potassium iodide in ionic liquid based on cyclic guanidinium cation(2) was investigated. The kinetic reasult shows that the rate of the reaction is enhanced in ionic liquid (2). The same reaction in [bmim][PF6](1)(where bmim = 1-butyl-3-methylimidazolium) was also studied. It was found that as a reaction medium ionic liquid (2) is better than (1) for nucelophilic displacement reactions.

Synthesis of cyclic carbonates from CO2 and epoxides catalyzed by hexaalkylguanidinium halides

Hexaalkylguanidinium halides exhibit an efficient catalytic activity in the synthesis of cyclic carbonates from, epoxides and carbon dioxide. By this method cyclic carbonates can be obtained in a high yield and a high selectivity at a low temperature and atmospheric pressure. This procedure is easy for the product isolation and recycling of the catalyst.