Regiospecific Synthesis and Structural Studies of 3,5-Dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-ones and Comparison with 1,3-Dihydro-2H-benzo[b][1,4]diazepin-2-ones.

Nine 3,5-dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-ones (17-25), some of which contain fluoro-substituents, have been regiospecifically prepared by reaction of 2,3-diaminopyridines with ethyl aroylacetates. In two cases, open intermediates have been isolated and these are related to the reaction pathway. The X-ray crystal structure of 1-methyl-4-phenyl-3,5-dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-one (23) has been solved (formula, C15H13N3O; crystal system, monoclinic; space group, C2/c). This is an asymmetric unit constituted by a single nonplanar molecule and its conformational enantiomer due to the presence of the seven-membered diazepin-2-one moiety, which introduces a certain degree of torsion in the adjacent pyridine ring. The 1H, 13C, 15N, and 19F NMR spectra were obtained and the chemical shifts, together with those of the previously published 1,3-dihydro-2H-benzo[b][1,4]diazepin-2-ones (1-16), i.e., a total of 544 values, were successfully compared with the chemical shifts calculated at the gauge invariant atomic orbital (GIAO)/Becke, three-parameter, Lee-Yang-Parr (B3LYP)/6-311++G(d,p) level. The seven-membered ring inversion barrier in 5-benzyl-2-phenyl-3,5-dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-one (25) was determined and, in conjunction with the data from the literature, compared with the B3LYP/6-311++G(d,p) computed values. This allowed the determination of several structural effects. The rotation about the exocyclic N1-CR bond was also calculated and its dynamic properties were discussed.

Statistical Tools for Air Pollution Assessment: Multivariate and Spatial Analysis Studies in the Madrid Region.

The present work reports the distribution of pollutants in the Madrid city and province from 22 monitoring stations during 2010 to 2017. Statistical tools were used to interpret and model air pollution data. The data include the annual average concentrations of nitrogen oxides, ozone, and particulate matter (PM10), collected in Madrid and its suburbs, which is one of the largest metropolitan places in Europe, and its air quality has not been studied sufficiently. A mapping of the distribution of these pollutants was done, in order to reveal the relationship between them and also with the demography of the region. The multivariate analysis employing correlation analysis, principal component analysis (PCA), and cluster analysis (CA) resulted in establishing a correlation between different pollutants. The results obtained allowed classification of different monitoring stations on the basis of each of the four pollutants, revealing information about their sources and mechanisms, visualizing their spatial distribution, and monitoring their levels according to the average annual limits established in the legislation. The elaboration of contour maps by the geostatistical method, ordinary kriging, also supported the interpretation derived from the multivariate analysis demonstrating the levels of NO2 exceeding the annual limit in the centre, south, and east of the Madrid province.