Ceftiofur [HRP]

The selective synthesis of 5,6-dihydropyrimidin-4(3H)-one scaffold (precursor of dihydrouracil) was a very difficult synthetic challenge that, so far, has not been achieved. For the first time, in this paper, green, selective and high-yields approach to 40 novel 5,6-dihydropyrimidin-4(3H)-ones (DHPMs) by one-pot reaction of aldehydes, Meldrum's acid and isothioureas under solvent-free conditions, in the presence of water, since an additive is presented. In the majority of cases, introduced methodology gave an unprecedented tautomer-selective fashion toward targeted compounds with excellent tautomeric purity (>99.9%), which reached 100% in few cases. The molecular structure of the five compounds has been determined by X-ray crystallography. In each one of them, very short length for the corresponding N2-C1 bond was noticed, making them especially interesting from a structural standpoint. This experimental fact can imply a highly localized electron pi density in this part of each heterocyclic ring. The obtained experimental results, which are determined from NMR and ESI-MS study, indicate that this Biginelli-type reaction smoothly proceeds in a one-pot mode, pointing to the three-step tandem process, proceeding via the Knoevenagel, aza-Michael, and retro-Diels-Alder reactions. The presented strategy also had the following advantages: reduction amount of waste, excellent values of green chemistry metrics (cEF, EcoScale and GCIS), and it is the first eco-friendly strategy toward the DHPMs scaffold.

Conventional site index (tree height at base age) may not be suitable for urban trees, therefore it is important to assess its applicability in urban environments. In addition, rapid and non-destructive tree age evaluation methods need to be developed. The objectives of this study were to: (1) develop a rapid and non-destructive method to determine tree age in urban environments, (2) examine the relationship between tree height, age, location, and soil type, and (3) compare the measured site indices with traditional site indices reported in Soil Survey Geographic Database (SSURGO). The study was conducted at the Clemson Experimental Forest (CEF) using conventionally-managed loblolly pine (Pinus taeda) stands, and loblolly pines in the urban environment of the Clemson University campus (CUC). Tree age obtained with a recording resistance drilling method and stump tree ring counting were comparable (R-2 = 0.98, n = 14). Tree age estimates from recording resistance drilling and from increment boring were also similar (R-2 = 0.93, n = 25). Replicate drilling samples had a low standard deviation, which indicated the high precision of the methodology. An additional benefit of the recording resistance drilling method is the ability to enable rapid evaluation of tree age across an urban forest. There was no discernible relationship between tree height and recording resistance drill age estimate for loblolly pines on the CUC (n = 25). In contrast, there was a relationship between measured diameter at breast height (DBH, cm) and recording resistance drill age estimates. A portion of the loblolly pine trees in the urban environment on the CUC appeared to have reduced productivity, as measured by the height/age relationship when predominantly surrounded by pavement or grass areas.