X‐ray crystallographic analysis and differential scanning calorimetry of two polymorphic forms of 2,6‐diphenyl‐1,4‐dithiin

2,6‐Diphenyl‐1,4‐dithiin 2 exists in the two polymorphic forms. The dithiin 2L , mp 62–63°C, was assigned as the metastable form, while the dithiin 2H , mp 79–80°C, was assigned as the stable form, mainly on the basis of differential scanning calorimetry (DSC) analysis. X‐Ray crystallographic analysis showed that the largest difference in the molecular structure between 2L and 2H is found in the coplanarity between the benzene ring and the double bond part of the dithiin ring; the benzene ring and the double bond are nearly coplanar for 2L , whereas these are far from being coplanar for 2H . © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:424–427, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20035     

Aza-pinacol rearrangement: acid-catalyzed rearrangement of aziridines to imines

A series of di-, tri-, and tetra-substituted N-tosylaziridines [N-(toluene-p-sulfonyl)aziridines] 1, prepared by aziridination of the corresponding alkenes with N-[(tolyl-p-sulfonyl)imino]phenyliodinane (TsN = IPh), was found to undergo a BF3-catalyzed rearrangement (aza-pinacol rearrangement) under mild conditions to give the corresponding N-tosylimines 2 generally in satisfactory yields.     

Induced circular dichroism spectra of the cyclodextrin complexes with 2-Thioxo-1,3-benzodithiole and 2-Selenoxo-1,3-benzodithiole

The induced circular dichroism (ICD) spectra of -cyclodextrin (-CD) complexes with 2-thioxo-1,3-benzodithiole and 2-selenoxo-1,3-benzodithiole have been measured. From the signs of the ICD spectra of both complexes, the polarization directions for the excited states have been investigated.     

Clinical significance of 99mTc-N-pyridoxyl-5-methyltryptophan (99mTc-PMT) in the diagnosis of intrahepatic masses

Hepatobiliary scintigraphy with 99mTc-N-pyridoxyl-5-methyltryptophan (99mTc-PMT) was carried out on 48 patients with intrahepatic masses, 44 with hepatocellular carcinoma and one each of hepatocellular adenoma, focal nodular hyperplasia, cholangiocellular carcinoma, and adenoid cystic carcinoma. Scans were performed twice, early scan (30 min post i.v.) and delayed scan (2.5 h post i.v.), and the delayed scan was used for assessing the accumulation of 99mTc-PMT in the intrahepatic masses. In the hepatocellular carcinoma group, based on individual patients, 17 out of 44 (38.6%) showed accumulation of 99mTc-PMT in various degrees; and based on individual masses, accumulation was noted in 21 out of 55 masses (38.2%). However, only the cases which had not received transarterial infusion of anti-cancer drugs (TAI) and/or blocking agents (TAE) were taken into consideration, 9 out of 18 patients (50%) and 12 out of 25 masses (48.0%) were found capable of picking up 99mTc-PMT. A case of hepatocellular adenoma showed a strong accumulation of 99mTc-PMT in the mass which was depicted as a defect on the 99mTc-colloid scan and did not show a significant accumulation of 67Ga. In a case of focal nodular hyperplasia, there were two space-occupying lesions (SOLs), one of which showed a clear-cut defect on the 99mTc-colloid scan and the other which showed only a distorted uptake pattern. However, both masses were strongly positive with 99mTc-PMT. 99mTc-PMT scintigraphy is useful in connection with 99mTc-colloid scan and sometimes with 67Ga-citrate in the diagnosis of intrahepatic masses originating from hepatocytes.     

Microwave spectrum,structure, dipole moment and internal rotation of ethyl fluorosilane

Microwave spectra of the trans and gauche isomers of ethyl fluorosilane and their eleven isotopically substituted species have been measured. The r_s structures of the two isomers were determined from the observed moments of inertia. The molecular structures found for the two isomers in the present study are compared with those of analogous molecules. Dipole moments of the two isomers were determined by Stark-effect measurements and are also compared with those of analogous molecules. The energy difference between the trans and gauche isomers was obtained from the relative intensity measurements of the spectra and the barrier to internal rotation of the methyl group for the gauche isomer was obtained from the A—E splittings of the spectra in the first excited methyl torsional state. The V₃ value was 2775 ± 25 cal mol^?1.     

Experimental study on the collimator for increasing the resolution of N-isopropyl-p-(123I)iodoamphetamine (IMP) SPECT imaging of the brain

This study was carried out to design a new collimator for the present 123I-IMP SPECT imaging of the brain, which is hindered by the contamination of 124I and 126I. In this study we intended to increase spacial resolution along the transaxial direction and, at the same time, to compensate for the decrease of sensitivity by sacrificing the resolution along the axial direction to some extent. For this purpose, we developed 4 kinds of slat type units; ultrahigh resolution (UHR), high resolution (HR), high sensitivity (HS), and ultrahigh sensitivity (UHS). In practice, either UHR or HR is set to the detector together with either HS or UHS. After testing 4 kinds of combinations, we found that the combination of UHR-HS gave us far better images than those obtained with the conventional medium energy parallel hole collimator and was best suited for 123I-IMP SPECT imaging of the brain at present. We are now thinking of fusing these two units together into one collimator.     

The stable inner salt 2,2‐dimorpholino‐2‐ethyl­ium‐1‐di­thio­ate

The title compound, C₁₀H₁₆N₂O₂S₂, is considered to maintain an inner‐salt structure in the crystal, where the planes of the carbenium and the thio­carboxyl­ate moieties are nearly perpendicular to each other [77 (2)°], and the backbone C—C bond length [N₂C—CS₂ 1.510 (2) Å] is significantly shorter than a normal C—C single‐bond length.     

First synthesis and characterization of isolable thioselenenic acid,triptycene-9-thioselenenic acid

Triptycene-9-thioselenenic acid was synthesized by hydrolysis of acetyl triptycene-9-thioselenenate, the structure of which was determined by spectroscopic data and X-ray diffraction analysis.