Studies on hindered phenols and analogues. V. Synthesis, identification, and antidiabetic activity of the glucuronide of CS-045.

The glucuronide of a new oral antidiabetic agent, (+/-)-5-[4-(6-hydroxy-2,5,7,8-tetramethylchroman-2-yl- methoxy)benzyl]thiazolidine-2,4-dione (CS-045) (1), was synthesized to confirm the structure of a metabolite in monkeys (Macaca fascicularis) and to examine its antidiabetic activity. The glucuronide also had antidiabetic activity in KK-mice.     

Catalysis Based on C−I⋅⋅⋅π Halogen Bonds: Electrophilic Activation of 2‐Alkenylindoles by Cationic Halogen‐Bond Donors for [4+2] Cycloadditions

Homo‐ and cross‐[4+2] cycloadditions of 2‐alkenylindoles, catalyzed by cationic halogen‐bond donors, were developed. Under mild reaction conditions, 3‐indolyl‐substituted tetrahydrocarbazole derivatives were obtained in good to excellent yields. Experimental and quantum calculation studies revealed that the electrophilic activation of 2‐alkenylindoles was achieved by C?I???π halogen bonds.     

Neues Verfahren zur Bestimmung der endständigen Carboxylgruppen von Peptiden

A new and simple method for the determination of the C-terminal groups of peptides is proposed. The carboxyl groups are converted into the corresponding peptide-triazines by treating with dimethylbiguanide. These derivatives are then hydrolysed by Streptomyces griseus protease and the amino-acid derivatives in the hydrolysate are identified by thin-layer or paper chromatography.     

Bisindolylmaleimides with large Stokes shift and long-lasting chemiluminescence properties

Various bisindolylmaleimides have fluorescence emission maxima wavelengths longer than 500 nm, large Stokes shifts longer than 200 nm, different fluorescence emission wavelengths at an excitation wavelength of 365 nm, and a long-lasting chemiluminescence. The expansion of the pi-conjugation, the pi-bond electronic structure, and oxidation of the C=C bond at the 2,3-position of the maleimide moiety are crucial for producing these fluorescence and chemiluminescence properties.     

Phosphatidylcholine-based nonaqueous photorheological fluids: effect of geometry and solvent

We report a detail study on photoinduced rheological changes in nonaqueous photorheological (PR) fluids obtained with 1,2-diacyl-sn-glycero-3-phosphocholine-based reverse wormlike micelles, 1-palmitoyl-2-oleophosphatidylcholine (POPC)/cyclohexane/H₂O, POPC/isooctane/H₂O, and L-α-dioleophosphatidylcholine (DOPC)/isooctane/H₂O systems. Initially, the mixtures form highly viscoelastic fluids of long, reverse wormlike micelles as confirmed by the rheological measurements. When photosensitive molecule, trans-CA, is added to these mixtures, they exhibit photosensitivity, and the viscoelasticity increases that decreases on UV irradiation. The nature of the substituent on the benzene ring of trans-CA influences the rheology. When hydroxycinnamic acid (HCA) (hydrophilic, ?OH group attached to the benzene ring of CA) is added to DOPC/isooctane/H₂O phase, separation occurs; while with the methoxycinnamic acid (MOCA) and methylcinnamic acid (MCA) (hydrophobic groups, ?OCH₃, and –CH₃ attached to the benzene ring of CA respectively) led to higher viscoelasticity. The study on the effects of position of the substitution on CA reveals the viscosity enhancement is in the order of p-?>?m-?>?o-isomers. The different geometries obtained because of substitution and photoinduced trans-cis isomerisation is responsible for the different rheology as confirmed by the dynamic rheology, the UV absorption, and the ¹H NMR spectrums. The ¹H NMR spectra revealed a change in the solubilization site of CA with irradiation. cis-CA (high solubility in water) is solubilized in the vicinity of water (at the hydrophilic end of DOPC) as compared with trans-CA. This disrupts the 3D networks of reverse wormlike micelles, decreasing the η ₀, plateau modulus, G _0, and relaxation time, τ _R of solution.     

Intramolecular SN'-type aromatic substitution of benzylic carbonates at their para-position

The benzylic carbonates, which connect with an active methine through an o-phenylene tether at their meta-position, are cyclized by Pd(η(3)-C(3)H(5))Cp-S-Phos catalyst, yielding 3-methyl-9,10-dihydrophenanthrenes. In the catalytic cyclization, the internal nucleophile attacks not the ortho-carbon but the para-carbon of the benzylic ester. The [3 + 2] cycloaddition of m-(silylmethyl)benzyl carbonates with alkylidene malonates was developed from the palladium-catalyzed intramolecular S(N)'-type aromatic substitution.     

Suzuki-Miyaura cross-coupling of benzylic carbonates with arylboronic acids

The cross-coupling of benzylic carbonates with arylboronic acids gave the corresponding diarylmethanes in high yields by use of the palladium catalyst generated in situ from [Pd(eta(3)-C(3)H(5))Cl](2) and 1,5-bis(diphenylphosphino)pentane (DPPPent). The Suzuki-Miyaura reaction using DPPPent-palladium catalyst is applicable to syntheses of a broad range of functionalized diarylmethanes. [reaction: see text]     

Suzuki-Miyaura coupling of diarylmethyl carbonates with arylboronic acids: a new access to triarylmethanes

Suzuki-Miyaura coupling of diarylmethyl carbonates with arylboronic acids proceeded in the presence of [Pd(eta3-C3H5)Cl]2-DPPPent (1,5-bis(diphenylphosphino)pentane) catalyst, yielding a variety of triarylmethanes.