Role of imine isomerization in the stereocontrol of the Staudinger reaction between ketenes and imines

Computational–experimental analysis has allowed determining that the stereochemistry of the Staudinger reaction between ketenes and imines is strongly associated with the nature of the imine, which affects the two steps of the reaction. The first step, namely the nucleophilic attack of the sp2-hybridized nitrogen atom of the imine on the sp-hybridized carbon atom of the ketene, is affected by the energetically accessible in situ isomerization patterns of the imine. The second step consists of a conrotatory electrocyclization of the zwitterionic intermediate formed in the previous step. This latter pericyclic step depends on the inward/outward torquoelectronic effects generated by the substituents of the imine. The impact of these factors on the stereochemistry of this reaction has been analyzed kinetically by numerical methods. The results of these simulations are compatible with the experimental results and support these conclusions

Leasing development in Latvia

Visizplatītākais un efektīvākais kreditēšanas veids Latvijā ir līzings. Līzinga daudzpusējā ietekme uz ekonomiku ir saistīta ar to, ka tas vienlaicīgi piesaista privātā kapitāla investīcijas ražošanas sfērā, uzlabo tiešo ražotāju finansiālo stāvokli un uzlabo to konkurētspēju. Par pāris gadu desmitiem , tas ir kļuvis ļoti pieejams gan privātpersonām, gan juridiskām personā. Tomēr pagaidām Latvijā vēl pastāv problēmas un to atrisinājuma iespējas. Bakalaura darba mērķis ir balstoties uz literatūras teorētiskajiem aspektiem, izpētīt un iepazīties ar līzinga veidiem, kā arī izanalizēt pašreizējo situāciju Latvijas līzingu tirgū, rezultātus apkopot secinājumos un atsevišķos priekšlikumos. Mērķu sasniegšanai tiek izvirzīti dažādi uzdevumi, līzinga būtības veidu un klasifikāciju izpēte, līzinga darījuma noslēgšanas kartības izvērtēšana, veikt līzinga darījumu tiesiskās bāzes izpēti Latvijā , kā arī analizēt lielākos līzinga uzņēmumus Latvijā un salīdzināt to ar kopējo Latvijas līzinga tirgu. Novērtēt līzinga darījuma riskus, izstrādāt secinājumus un priekšlikumus par līzinga attīstības iespējām Latvija. Pēc veiktajiem uzdevumiem, var secināt, ka līzingu attīstību Latvijā varētu stimulēt un uzlabot atsevišķa līzinga likuma izveide. Bakalaura darba nosaukums ir „līzinga attīstība Latvijā”. Darba apjoms sastāda 64 lappuses. Darbā tiek izmantoti 49 literatūras un informācijas avoti. Bakalaura darbs satur 4 tabulas un 16 attēlus.The most common and the most efficient form of lending in Latvia is lease. Multilateral impact of lease on the economic concerned with the fact that it attracts private capital investment in the manufacturing sector, improves the financial situation of the direct manufacturers and improves their competitiveness simultaneously. It has become very accessible for individuals and entities during the last few decades. However, there are still problems and opportunities of its solution in Latvia. The target of Bachelor's work is not only to research and to learn the types of lease using the theoretical aspects of literature, but also to analyze the current situation of the Latvian leasing market and to make the conclusions and some proposals. There are pursued different tasks for achieving the target: researching the substance and classification of lease, assessment of procedure of closing the deal of lease, researching the legal basis of lease in Latvia, as well as the analysis of the major Latvian leasing companies and its comparison with the total Latvian leasing market; estimating of the leasing transaction risks, making conclusions and proposals for leasing development in Latvia. After the pursued tasks fulfillment it can be concluded that the development of the Latvian leasing could be stimulated and improved by creation of leasing law. Bachelor's work title is "Development of Latvian leasing." Work consists of 64 pages. There are 49 sources of literature and information used in work. Bachelor's work consists of 4 tables and 16 images

Mechanistic insight into the facilitation of β-lactam fragmentation through metal assistance

Communication.-- Titulo del pdf: Making Easier the β-Lactam Fragmentation via Metal-Assistance: Mechanistic Insight.The mechanism of OsH6(PiPr3)2-mediated fragmentation of a 4-(2 pyridyl)-2-azetidinone has been investigated by DFT calculations. The addition of the C4-H bond of the substrate to OsH2(PiPr3)2 allows the active participation of an osmium lone pair in the B-type b-lactam fragmentation process. This new mechanism makes the N1-C4/C2-C3 fragmentation of the lactamic core thermally accessible through a stepwise process.Financial support from the Spanish MINECO and FEDER (Projects CTQ2013-46459-C2-01-P, CTQ2014-52799-P, CTQ2014-54071-P, and CTQ2014-51912-REDC), the DGA (E35), and the European Social Fund (FSE) is acknowledgedPeer reviewe

Chelated Assisted Metal-Mediated N–H Bond Activation of β‑Lactams: Preparation of Irida‑, Rhoda‑, Osma‑, and Ruthenatrinems

2-Azetidinones substituted with pyridine (<b>2a</b>), quinoline (<b>2b</b>), isoquinoline (<b>2c</b>), imidazole (<b>2d</b>), and benzimidazole (<b>2e</b>) at the 4-position of the four-membered ring have been prepared in order to synthesize tribactams containing a transition metal and its associated ligands, L_<i>n</i>M, at the 2-position of the tricyclic skeleton. The developed procedure is compatible with a wide range of transition-metal starting complexes. Thus, the iridium and rhodium dimers [M­(η⁵-C₅Me₅)­Cl₂]₂ react with <b>2a</b>–<b>e</b>, in the presence of sodium acetate, to afford irida- and rhodatrinems (<b>1a</b>–<b>j</b>) containing the half-sandwich d⁶ metal fragments M­(η⁵-C₅Me₅)Cl (M = Ir, Rh). The reactions of [M­(μ-OMe)­(η⁴-COD)]₂ (M = Ir, Rh) with <b>2a</b> lead to irida- and rhodatrinems (<b>1k</b>,<b>l</b>) with the d⁸ moieties M­(η⁴-COD). The coordination sphere and oxidation state of the metal center in these compounds can be modified, without affecting the 2-azetidinone backbone, by means of substitution and oxidative addition reactions. As a proof of concept, metallatrinems with the M­(CO)₂ (M = Ir (<b>1m</b>), Rh (<b>1n</b>)) and Ir­(Me)­I­(CO)₂ (<b>1o</b>) units are also reported. Osmatrinems <b>1p</b>,<b>q</b> containing the d⁴ metal fragment OsH₃(PⁱPr₃)₂ have been obtained starting from the d² hexahydride OsH₆(PⁱPr₃)₂, by reaction with <b>2a</b>,<b>b</b>, whereas the treatment of the tetrahydroborate complexes MH­(η²-H₂BH₂)­(CO)­(PⁱPr₃)₂ (M = Os, Ru) with <b>2a</b> yields osma- and ruthenatrinems (<b>1r</b>,<b>s</b>) containing six-coordinate bis­(phosphine) d⁶ metal fragments. The IR stretching frequency of the lactamic carbonyl, the bent angle between the five- and four-membered rings of the tricycle, and the N–CO bond length in the lactamic ring are clearly infuenced by the L_<i>n</i>M fragment

Ticagrelor in patients with diabetes and stable coronary artery disease with a history of previous percutaneous coronary intervention (THEMIS-PCI) : a phase 3, placebo-controlled, randomised trial

Background: Patients with stable coronary artery disease and diabetes with previous percutaneous coronary intervention (PCI), particularly those with previous stenting, are at high risk of ischaemic events. These patients are generally treated with aspirin. In this trial, we aimed to investigate if these patients would benefit from treatment with aspirin plus ticagrelor. Methods: The Effect of Ticagrelor on Health Outcomes in diabEtes Mellitus patients Intervention Study (THEMIS) was a phase 3 randomised, double-blinded, placebo-controlled trial, done in 1315 sites in 42 countries. Patients were eligible if 50 years or older, with type 2 diabetes, receiving anti-hyperglycaemic drugs for at least 6 months, with stable coronary artery disease, and one of three other mutually non-exclusive criteria: a history of previous PCI or of coronary artery bypass grafting, or documentation of angiographic stenosis of 50% or more in at least one coronary artery. Eligible patients were randomly assigned (1:1) to either ticagrelor or placebo, by use of an interactive voice-response or web-response system. The THEMIS-PCI trial comprised a prespecified subgroup of patients with previous PCI. The primary efficacy outcome was a composite of cardiovascular death, myocardial infarction, or stroke (measured in the intention-to-treat population). Findings: Between Feb 17, 2014, and May 24, 2016, 11 154 patients (58% of the overall THEMIS trial) with a history of previous PCI were enrolled in the THEMIS-PCI trial. Median follow-up was 3·3 years (IQR 2·8–3·8). In the previous PCI group, fewer patients receiving ticagrelor had a primary efficacy outcome event than in the placebo group (404 [7·3%] of 5558 vs 480 [8·6%] of 5596; HR 0·85 [95% CI 0·74–0·97], p=0·013). The same effect was not observed in patients without PCI (p=0·76, p interaction=0·16). The proportion of patients with cardiovascular death was similar in both treatment groups (174 [3·1%] with ticagrelor vs 183 (3·3%) with placebo; HR 0·96 [95% CI 0·78–1·18], p=0·68), as well as all-cause death (282 [5·1%] vs 323 [5·8%]; 0·88 [0·75–1·03], p=0·11). TIMI major bleeding occurred in 111 (2·0%) of 5536 patients receiving ticagrelor and 62 (1·1%) of 5564 patients receiving placebo (HR 2·03 [95% CI 1·48–2·76], p<0·0001), and fatal bleeding in 6 (0·1%) of 5536 patients with ticagrelor and 6 (0·1%) of 5564 with placebo (1·13 [0·36–3·50], p=0·83). Intracranial haemorrhage occurred in 33 (0·6%) and 31 (0·6%) patients (1·21 [0·74–1·97], p=0·45). Ticagrelor improved net clinical benefit: 519/5558 (9·3%) versus 617/5596 (11·0%), HR=0·85, 95% CI 0·75–0·95, p=0·005, in contrast to patients without PCI where it did not, p interaction=0·012. Benefit was present irrespective of time from most recent PCI. Interpretation: In patients with diabetes, stable coronary artery disease, and previous PCI, ticagrelor added to aspirin reduced cardiovascular death, myocardial infarction, and stroke, although with increased major bleeding. In that large, easily identified population, ticagrelor provided a favourable net clinical benefit (more than in patients without history of PCI). This effect shows that long-term therapy with ticagrelor in addition to aspirin should be considered in patients with diabetes and a history of PCI who have tolerated antiplatelet therapy, have high ischaemic risk, and low bleeding risk