Double lactonization in triarylamine-conjugated dimethyl diethynylfumarate: formation of intensely colored and luminescent quadrupolar molecules including a missing structural isomer of Pechmann dyes

Acid-induced double lactonization in triarylamine-conjugated dimethyl diethynylfumarate E-1 opens up a new synthetic route to Pechmann dyes. This one-pot reaction affords three donor-acceptor-donor quadrupolar molecules (P(55)-1, P(66)-1, and P(56)-1); P(56)-1 comprises a missing structural isomer of Pechmann dyes. They are intensely colored and brightly luminescent. An organic field-effect transistor device fabricated with P(66)-1 functions as a p-type semiconductor.     

Non-uniformity correction of human brain imaging at high field by RF field mapping of B1+ and B1-

A new method of non-uniform image correction is proposed. Image non-uniformity is originated from the spatial distribution of RF transmission and reception fields, represented as B(1)(+) and B(1)(-), respectively. In our method, B(1)(+) mapping was performed invivo by a phase method. In B(1)(-) mapping, images with multiple TEs were acquired with a multi-echo adiabatic spin echo (MASE) sequence which enables homogeneous excitation. By T(2) fitting of these images an M(0) map (M(0)(MASE)) was obtained, in which signal intensity was expressed as the product of B(1)(-) and M?(1-e?(TR/T1)) . The ratio of this M(0)(MASE) map to the B(1)(+) map showed a similar spatial pattern in different human brains. These ratios of M(0)(MASE) to B(1)(+) in 24 subjects were averaged and then fitted with a spatially polynomial function to obtain a ratio map of B(1)(-)/B(1)(+)(α). Uniform image was achieved in spin echo (SE), MASE and inversion recovery turboFLASH (IRTF) images using measured B(1)(+) and calculated B(1)(-) by αB(1)(+). Water fractions in gray and white matters obtained from the M(0) images corrected by this method were in good agreement with previously reported values. From these experimental results, the proposed method of non-uniformity correction is validated at 4.7 T imaging.     

Cyclodehydration of cis-2-butene-1,4-diol with active methylene compounds catalyzed by a diphosphinidenecyclobutene-coordinated palladium complex

(π-Allyl)palladium triflate coordinated with 1,2-bis(4-methoxyphenyl)-3,4-bis(2,4,6-tri-t-butylphenylphosphinidene)cyclobutene (DPCB-OMe), [Pd(η³-C₃H₅)(DPCB-OMe)]OTf, efficiently catalyzes cyclodehydration of cis-2-butene-1,4-diol with active methylene compounds such as acetylacetone and ethyl acetoacetate in toluene in the presence of pyridine. The reactions can be performed in air, giving 2-vinyl-2,3-dihydrofurans in good to high yields.     

A new assignment technique of 2D‐NMR spectra by spin‐lock sequence to a tripeptide containing tryptophan in water

We developed a new assignment technique of tryptophan residues using pulsed field gradient TOCSY–ROESY (PFG‐TORO) and pulsed field gradient TOCSY–ROESY–TOCSY (PFG‐TOROTO) techniques in water. Connectivity from βH to ζ2H (H‐7) via ε1H (H‐1) and δ1H (H‐2) in the TORO spectrum and from βH to ζ3H (H‐5) and η2H (H‐6) via ε1H (H‐1) and δ1H (H‐2) in the TOROTO spectrum could be able to assign each of the protons of the indole rings. Copyright © 2010 John Wiley & Sons, Ltd.     

Infrared spectra of the CF3I dimer: a concurrent application of matrix-isolation spectroscopy and cavity ring-down spectroscopy

We have observed infrared spectra of the CF(3)I dimer produced in a supersonic jet by matrix-isolation Fourier transform infrared spectroscopy and infrared cavity ring-down (IR-CRD) spectroscopy. In the matrix-isolation experiments, the dimer was isolated in an Ar matrix by the pulse-deposition method. The recorded spectral range covers the symmetric (nu(1)) and doubly degenerate (nu(4)) C-F stretching regions. From the concentration dependence of the matrix-isolation spectra we have assigned one dimer band for each fundamental region. It was not easy to identify the dimer band for the nu(4) band because of the multiplet feature of the monomeric nu(4) band caused by the site symmetry breaking. The spectra of (CF(3)I)(2) in the nu(4) band region were thus also measured in the gas phase by IR-CRD spectroscopy, where we detected two dimer bands. Comparing the observed band positions with the results of quantum chemical calculations, we have assigned the observed dimer bands to the head-to-head isomer. The structure of (CF(3)I)(2) and its photochemical implications are discussed, in comparison with methyl iodide dimer reported previously [Ito et al., Chem. Phys. Lett. 343, 185 (2001)].     

Paeoniflorigenone,a new monoterpene from paeony roots

Paeoniflorigenone (1), a new monoterpene which produces a neuromuscular-blocking effect in mice, was isolated from paeony roots and its structure was elucidated.     

Configurational studies on amylose. II. Moments and distribution functions

Statistical mechanical averages of vectors and tensors characterizing the configuration of amylose chains have been calculated. These quantities are expressed in the reference frame affixed to the first glucose unit, the x axis being situated along the O(4)—O(1) virtual bond vector, and the Y axis in the plane of the virtual bond and the O(4)—C(4) bond. The persistence vector a as defined by the average of the end-to-end vector r converges slowly to the limiting persistence vector a _∞ with increasing chain length. Configurational averages of the Cartesian tensors formed from the displacement vector ρ = r ? a have been computed up to seventh rank according to the generator matrix method. The density distribution functions W_α (ρ) evaluated for x_u = 40 by using the three-dimensional Hermite polynomial expansion truncated at the term involving the tensor of seventh rank are approximately cylindrically symmetric about one of the principal axes of the second-moment tensor <ρ^×2. The density distribution function W_α(ρ) is slightly asymmetric even for x_u = 80.     

Scillapersicene: a new homoisoflavonoid with cytotoxic activity from the bulbs of Scilla persica HAUSSKN

The phytochemical investigation of Scilla persica HAUSSKN bulbs led to the isolation of a novel homoisoflavonoid that named Scillapersicene (1) and identified as 3-(3′,4′-dihydroxybenzylidene)-8-hydroxy-5,7-dimethoxychroman-4-one along with five known homoisoflavonoids 2–6, whose structures were elucidated using HRFAB-MS, 1D and 2D NMR spectroscopic data. The known compounds were identified as 3-(3′,4′-dihydroxybenzyl)-5,8-dihydroxy-7-methoxychroman-4-one (2), 3,9-dihydro-autumnalin (3), autumnalin (4), 3-(3′,4′-dihydroxybenzylidene)-5,8-dihydroxy-7-methoxychroman-4-one (5) and scillapersicone (6). All compounds obtained, expect 2 and 4, showed strong cytotoxic activity against AGS cell line. The toxicity on AGS cell line was measured by 1, 3, 5 and 6 with IC₅₀ values of 8.4, 30.5, 10.7 and 24.2 μM, respectively. In addition, the physico-chemical properties of these natural compounds were optimised using density functional method (B3LYP) with standard 6-311+G* basis set. These natural products have low-energy gaps between the first ionisation potentials and highest occupied molecular orbital. In conclusion, the low-energy gap could cause reason for cytotoxic activity of homoisoflavonoids.     

Two new monoterpene glycosides and trypanocidal terpenoids from Dracocephalum kotschyi

From the whole plant of Dracocephalum kotschyi BOISS., two new monoterpene glycosides (9, 10), together with seven known terpenoids and a phytosterol (1-8), were isolated. Their structures were determined to be limonen-10-al (1), geranial (2), neral (3), beta-sitosterol (4), oleanolic acid (5), ursolic acid (6), p-mentha-8-en-1,2-diol (7), colosolic acid (8), limonen-10-ol 10-O-beta-D-glucopyranoside (9), and limonen-10-ol 10-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside (10). Compounds 1 (3.1 microM), 2 (3.1 microM), 3 (3.1 microM), 5 (6.2 microM), 6 (6.2 microM), and 8 (6.2 microM) were effective against epimastigotes of Trypanosoma cruzi.