Reaction cascades initiated by nucleophilic attack of heteropentalene mesomeric betaine and nitrogen-rich mesoionic tetrazolium-5-amides on electron-deficient unsaturated compounds. Synthesis of novel heterocyclic systems.
The reactions of heteropentalene mesomeric betaine 1 and nitrogen-rich mesoionic tetrazolium-5-amides 4, 11 and 16-18 with electron-deficient unsaturated compounds have been studied. Novel heterocyclic systems, tetrazolo[4,5-a][1,7]benzodiazonine inner salt 2 and 3-oxo-3,7-dihydro-2H-pyrazolo[3,4-b]pyridine 5, have been synthesized by the reactions of dimethyl acetylenedicarboxylate with 1 and tetrazolium-5-anilide 4, respectively, and fully characterized by X-ray crystallography. It has been found that the reactions of other tetrazolium-5-amides are also initiated by the nucleophilic addition of the electron-rich amide nitrogen to the electron-deficient unsaturated compounds.
Mesomeric betaines constructed of quinolinium cations and carboxylate anions separated by thiophene-ethynyl spacers as fluorescent dipoles
4- and 5-((1-Methylquinolinium-3-yl)ethynyl)thiophene-2-carboxylates were prepared starting from 3-ethynylquinoline which was subjected to a Sonogashira-Hagihara coupling with ethyl 4- and 5-bromothiophenecarboxylates, respectively. Methylation to give the corresponding quinolinium salts, saponification under basic conditions, acidification to give the carboxylic acids, and basification finally yielded the title compounds. Calculations of the frontier orbital profiles confirm the classification of these mesomeric betaines as cross-conjugated systems, as the HOMO is essentially located in the carboxylate group which is connected to the spacer by a nodal position. Fluorescence spectroscopic investigations were performed.
ASSESSING AGE AND GENDER DIFFERENCES IN PERCEIVED RISK AND FEAR OF CRIME
Much of the research on fear of crime indicates that women and older persons are highly afraid of crime. These findings, especially older persons' fear of crime, are widely communicated in the scientific and popular media. This study examines age and gender differences in perceived risk and fear of crime. The data are from telephone interviews of 320 randomly selected residents in a southeastern metropolitan area of the United States. The relationships of age and gender to fear of crime are compared using a National Crime Survey (NCS) measure of fear of crime and 11 alternative indicators of fear of specific offenses. Women reported signifcantly greater perceived risk and fear of crime than men regardless of how fear of crime was measured and older adults reported the greatest fear of crime when the NCS measure was used. but not when the alternative individual measures of fear of crime were used. A LISREL model with latent constructs for fear of personal crime and fear of property crime also indicates that older adults do not have higher levels of fear of crime. In short, the extent of fear in the everyday lives of most older persons has been overestimated in many previous studies because of measurement problems.