Chiral phosphoric Acid catalyzed transfer hydrogenation: facile synthetic access to highly optically active trifluoromethylated amines

Amines to an end: Highly optically active α-CF(3) -functionalized amines can be obtained using metal-free reaction conditions. The method involves the transfer hydrogenation of CF(3) -substituted ketimines catalyzed by 1 and reductive amination of CF(3) -substituted ketones. The synthetic utility of this method was demonstrated by the synthesis of a CF(3) analogue of NPS?R-568. PMP=para-methoxyphenyl.     

Device for co-culture of sympathetic neurons and cardiomyocytes using microfabrication

Rat superior cervical ganglion (SCG) neurons and ventricular myocytes (VMs) were co-cultured separately in a minichamber placed on a microelectrode-array (MEA) substrate. The minichamber, fabricated photolithographically using polydimethylsiloxane (PDMS), had 2 compartments, 16 microcompartments and 8 microconduits. The SCG neurons were seeded into one of the compartments and all of the microcompartments using a glass pipette controlled by a micromanipulator and a microinjector. The VMs were seeded into the other compartment. Three days after seeding of the VMs, the SCG neurons were still confined to one compartment and all of the microcompartments, and the neurites of the SCG neurons had connected with the VMs via the microconduits. Constant-voltage stimulation, using a train of biphasic square pulses (1 ms at +1 V, followed by -1 ms at 1 V), was applied to the SCG neurons in the microcompartments using 16 electrodes. Evoked responses were observed in several electrodes while electrical stimulation was applied to the SCG neurons. Two-way analysis of variance (ANOVA) revealed that the frequency of the stimulation pulses had significant effects in increasing the beat rate of the VMs, and that the interaction between the frequency and the number of the pulses also had a significant effect on the ratio. No significant increases in the beat rate were observed when propranolol, a β-adrenergic receptor antagonist, was added to the culture medium. These results suggest that synaptic pathways were formed between the SCG neurons and the VMs, and that this co-culture device can be utilized for studies of network-level interactions between sympathetic neurons and cardiomyocytes.     

Bridged nucleic acid conjugates at 6'-thiol: synthesis, hybridization properties and nuclease resistances

The bridged nucleic acid (BNA) containing a thiol at the 6'-position in the bridged structure was synthesized from the disulfide-type BNA and conjugated with various functional molecules via the thioether or the disulfide linkage post-synthetically and efficiently in solution phase. The disulfide-linked conjugate was cleaved under reductive conditions derived from glutathione and an oligonucleotide bearing a free thiol was released smoothly. Conjugated functional molecules had great effects on duplex stability with the DNA complement. In contrast, the molecules little influenced the stability with the RNA complement. Moreover, the oligonucleotides with functional groups at the 6'-position had as high or higher resistances against 3'-exonuclease than phosphorothioate oligonucleotide (S-oligo).     

Syntheses and reactivities of non-symmetrical "active ester" bi-dentate cross-linking reagents having a phthalimidoyl and acid chloride, 2-benzothiazole, or 1-benzotriazole group

We have newly synthesized the non-symmetrical "phthalimidoyl active ester" bi-dentate cross-linking reagents having an acid chloride, 2-benzothiazole, or 1-benzotriazole group (i.e., 9, 15, and 16) on the basis of the reactivity study of the "active ester" model compounds, 11-14, toward the various nucleophiles and examined their reaction selectivity towards the same nucleophiles. Then, we applied for the modification of cholesterol at the more reactive site of the bi-dentate linkers to give 3β-cholesteryl 4-(phthalimidoyloxycarbonyl)butyrate (39), and the subsequent reaction of 39 with several amines, such as benzylamine, 4-chlorobenzylamine, 2-phenylethylamine, L-phenylalanine methyl ester, or diphenylalanine benzyl ester as a protein model of the cholesterol antigen.     

Three-component coupling using arynes and DMF: straightforward access to coumarins via ortho-quinone methides

ortho-Quinone methides, arising from a formal [2+2] cycloaddition between arynes and DMF, were found to facilely undergo a [4+2] cycloaddition with ester enolates or ketenimine anions to produce diverse coumarins in a straightforward manner.     

Highly crystalline and conductive nitrogen-doped mesoporous carbon with graphitic walls and its electrochemical performance

We present a rational and simple methodology to fabricate highly conductive nitrogen-doped ordered mesoporous carbon with a graphitic wall structure by the simple adjustment of the carbonization temperature of mesoporous carbon nitride without the addition of any external nitrogen sources. By simply controlling the heat-treatment temperature, the structural order and intrinsic properties such as surface area, conductivity, and pore volume, and the nitrogen content of ordered graphitic mesoporous carbon can be controlled. Among the materials studied, the sample heat-treated at 1000 °C shows the highest conductivity, which is 32 times higher than that for the samples treated at 800 °C and retains the well-ordered mesoporous structure of the parent mesoporous carbon nitride and a reasonable amount of nitrogen in the graphitic framework. Since these materials exhibit high conductivity with the nitrogen atoms in the graphitic framework, we further demonstrate their use as a support for nanoparticle fabrication without the addition of any external stabilizing or size-controlling agent, as well as the anode electrode catalysts. Highly dispersed platinum nanoparticles with a size similar to that of the pore diameter of the support can be fabricated since the nitrogen atoms and the well-ordered porous structure in the mesoporous graphitic carbon framework act as a stabilizing and size-controlling agent, respectively. Furthermore the Pt-loaded, nitrogen-doped mesoporous graphitic carbon sample with a high conductivity shows much higher anodic electrocatalytic activity than the other materials used in the study.     

Deprotonation‐Induced Aromaticity Enhancement and New Conjugated Networks in meso‐Hexakis(pentafluorophenyl)[26]hexaphyrin

meso‐Hexakis(pentafluorophenyl)‐substituted neutral hexaphyrin with a 26π‐electronic circuit can be regarded as a real homolog of porphyrin with an 18π‐electronic circuit with respect to a quite flat molecular structure and strong aromaticity. We have investigated additional aromaticity enhancement of meso‐hexakis(pentafluorophenyl)[26]hexaphyrin(1.1.1.1.1.1) by deprotonation of the inner N? H groups in the macrocyclic molecular cavity to try to induce further structural planarization. Deprotonated mono‐ and dianions of [26]hexaphyrin display sharp B‐like bands, remarkably strong fluorescence, and long‐lived singlet and triplet excited‐states, which indicate enhanced aromaticity. Structural, spectroscopic, and computational studies have revealed that deprotonation induces structural deformations, which lead to a change in the main conjugated π‐electronic circuit and cause enhanced aromaticity.