Stereoselective synthesis of withafein A and 27-deoxywithaferin A1

The first stereoselective synthesis of withaferin A and 27-deoxywithaferin A was described. The key steps in the synthesis involve introduction of the desired substituent at C₂₅ and steroselective construction of the A:B rings by a facile allyl sulfoxide—sulfenate rearrangement.     

Preparation of benzoheterocycles containing a chlorofluoromethyl group using the ‘Yarovenko reagent’

ortho-Bifunctional benzenes such as 2-aminophenol o-phenylenediamine, 2-aminothiophenol, 2-aminobenzamide and catechol reacted very easily with 2-chloro-1,1,2-trifluoroethyldiethlylamine, the ‘Yarovenko reagent,’ affording 2-(chlorofluoromethyl)benzoxazole, -benzoimidazole, -benzothiazole, 2-(chlorofluoromethyl)-4-quinazolone and 2-diethylamino-2-(chlorofluoromethyl)dioxole respectively.     

Polarization labelling spectroscopy of the A 1Σ+u band of Na2

A result of the polarization labelling spectroscopy of the A ¹Σ⁺_u band of sodium dimer for the high vibrational quantum number υ'>20 is reported. The frequency difference δv=v_obs-v_cal is found to decrease from 2 to -3 cm^-1 as the rotational levels (υ'=27?30), where v_cal is the calculated transition frequency using the Dunham coefficients of Demtröder and Stock for the X ¹Σ⁺_g band and of Kusch and Hessel for the A ¹Σ⁺_u band.     

Electron-transfer polymers. XL. Redox polyamides

By condensing a hydroquinone bis-lactone of 1,4-dihydroxybenzene-2,5-bis(ethyl-2′-carboxylic acid) with diamines such as hexamethylene diamine, piperazine, 4-aminoethylpiperidine, or 1,3-di-(4′-piperidinyl) propane, redox polyamides can be prepared. The lactone functions protect the hydroxyl groups until the polymerization occurs at which point, due to the opening of the lactone rings, free hydroquinone hydroxyls appear. The resulting polymer is oxidizable. When the oxidized polymer is reduced the viscosity is higher than that of the original reduced polymer.     

The improved synthesis of OPC-29030, a platelet adhesion inhibitor via diastereoselective oxidation of chiral non-racemic sulfide

An improved synthetic route of OPC-29030, the platelet adhesion inhibitor, was established via the diastereoselective oxidation of a chiral non-racemic sulfide (R)-5 to (S(S))-6 by the catalytic oxidation using VO(acac)(2) and cumene hydroperoxide (CHP) in the presence of MS4A. Under the current condition, the diastereoselectivity was not influenced by the presence of moisture, and moderate to high selectivity (72% de) was obtained at -30 degrees C. The obtained sulfoxide, which diastereomeric excess was easily raised by the recrystallization, could successfully lead to OPC-29030.     

A new cyclopentanone annulation of α-bromomethylacrylates

Direct couplings of the α-bromomethylacrylates and the doubly charged succinate ion are described.     

Selective scavenging property of the indole moiety for the nitrating species of peroxynitrite

The inhibitory effect on tyrosine nitration and oxidation of peroxynitrite was evaluated for more than 40 reagents including natural and synthetic compounds, and the inhibiting efficiency of each compound for nitration was compared with that for oxidation, to characterize its property as a peroxynitrite scavenger. In the presence of various concentrations of testing compounds, the nitrating and oxidizing activities were measured by monitoring the formation of 3-nitrotyrosine and dityrosine with an HPLC-UV-fluorescence detector. The IC(50) values for nitration and oxidation were determined, and the ratio of these two IC(50) values was calculated for each compound. Although the IC(50) values varied from compound to compound, it was revealed that the ratio of two IC(50) values (IC(50) for oxidation/IC(50) for nitration) was 1 in almost all the compounds tested, except five indole derivatives (L-tryptophan, melatonin, 5-methoxytryptamine, tryptamine, and tetrahydro-beta-carboline) and one synthetic selenium-containing compound ((2R,3R,4S)-2-amino-3,4-dihydroxy-5-phenylselenopentan-1-ol, ADPP). The indole derivatives showed a specific inhibitory effect on tyrosine nitration without affecting the oxidation. ADPP was confirmed to have a preferable inhibitory activity for tyrosine oxidation. It was suggested that compounds showing an IC(50) value ratio of 1 scavenged the common species for nitration and oxidation, while the indole derivatives and ADPP preferably scavenged the nitrating and oxidizing species, respectively. From a stopped flow study, it was also revealed that the nitrotyrosine formation was relatively slow, unlike an OH radical reaction. These results imply that the peroxynirite reaction at least partly proceeds through specific species for nitration.