Desymmetrisation reactions of cyclohexa-1,4-dienes

This thesis describes the development of diastereotopic group selective processes allowing the desymmetrisation of 1,4-cyclohexadiene derivatives and their application to target synthesis. Chapter 1 discusses some of the benefits that may be derived by the use of desymmetrisation, and demonstrates some of the ways in which it has recently been applied in compounds based on 1,4-cyclohexadiene. Chapter 2 describes a novel use of the Prins reaction to desymmetrise cyclohexadiene derivatives with high diastereoselectivity, and the optimisation of this resulting in an effective, practical and straightforward procedure. Chapter 3 details the investigation into desymmetrisation through diastereoselective iodocyclisation reactions, much higher stereoselectivity is observed than found previously in cyclohexadiene based substrates and an explanation is suggested by examination of structural differences. Chapter 4 reviews some of the previous synthetic approaches to members of the fawcettimine group of Lycopodium alkaloids. This is followed by the results of our first approach to the core tetracyclic ring system of lycoposerramine A, based on the discovery of a novel base induced diastereotoselective cyclisation reaction. Chapter 5 describes our revised approach, leading to the construction of a closely related tetracycle, although not permitting the construction of the target. Chapter 6 discusses the synthesis of the core tricyclic system of lycoposerramine S by a different strategy. NMR spectra obtained from the final product are found to closely match those obtained from the natural product

Clinical Significance of Bronchodilator Responsiveness Evaluated by Forced Vital Capacity in COPD: SPIROMICS Cohort Analysis.

ObjectiveBronchodilator responsiveness (BDR) is prevalent in COPD, but its clinical implications remain unclear. We explored the significance of BDR, defined by post-bronchodilator change in FEV1 (BDRFEV1) as a measure reflecting the change in flow and in FVC (BDRFVC) reflecting the change in volume.MethodsWe analyzed 2974 participants from a multicenter observational study designed to identify varying COPD phenotypes (SPIROMICS). We evaluated the association of BDR with baseline clinical characteristics, rate of prospective exacerbations and mortality using negative binomial regression and Cox proportional hazards models.ResultsA majority of COPD participants exhibited BDR (52.7%). BDRFEV1 occurred more often in earlier stages of COPD, while BDRFVC occurred more frequently in more advanced disease. When defined by increases in either FEV1 or FVC, BDR was associated with a self-reported history of asthma, but not with blood eosinophil counts. BDRFVC was more prevalent in subjects with greater emphysema and small airway disease on CT. In a univariate analysis, BDRFVC was associated with increased exacerbations and mortality, although no significance was found in a model adjusted for post-bronchodilator FEV1.ConclusionWith advanced airflow obstruction in COPD, BDRFVC is more prevalent in comparison to BDRFEV1 and correlates with the extent of emphysema and degree of small airway disease. Since these associations appear to be related to the impairment of FEV1, BDRFVC itself does not define a distinct phenotype nor can it be more predictive of outcomes, but it can offer additional insights into the pathophysiologic mechanism in advanced COPD.Clinical trials registrationClinicalTrials.gov: NCT01969344T4

Common Genetic Polymorphisms Influence Blood Biomarker Measurements in COPD

Implementing precision medicine for complex diseases such as chronic obstructive lung disease (COPD) will require extensive use of biomarkers and an in-depth understanding of how genetic, epigenetic, and environmental variations contribute to phenotypic diversity and disease progression. A meta-analysis from two large cohorts of current and former smokers with and without COPD [SPIROMICS (N = 750); COPDGene (N = 590)] was used to identify single nucleotide polymorphisms (SNPs) associated with measurement of 88 blood proteins (protein quantitative trait loci; pQTLs). PQTLs consistently replicated between the two cohorts. Features of pQTLs were compared to previously reported expression QTLs (eQTLs). Inference of causal relations of pQTL genotypes, biomarker measurements, and four clinical COPD phenotypes (airflow obstruction, emphysema, exacerbation history, and chronic bronchitis) were explored using conditional independence tests. We identified 527 highly significant (p 10% of measured variation in 13 protein biomarkers, with a single SNP (rs7041; p = 10−392) explaining 71%-75% of the measured variation in vitamin D binding protein (gene = GC). Some of these pQTLs [e.g., pQTLs for VDBP, sRAGE (gene = AGER), surfactant protein D (gene = SFTPD), and TNFRSF10C] have been previously associated with COPD phenotypes. Most pQTLs were local (cis), but distant (trans) pQTL SNPs in the ABO blood group locus were the top pQTL SNPs for five proteins. The inclusion of pQTL SNPs improved the clinical predictive value for the established association of sRAGE and emphysema, and the explanation of variance (R2) for emphysema improved from 0.3 to 0.4 when the pQTL SNP was included in the model along with clinical covariates. Causal modeling provided insight into specific pQTL-disease relationships for airflow obstruction and emphysema. In conclusion, given the frequency of highly significant local pQTLs, the large amount of variance potentially explained by pQTL, and the differences observed between pQTLs and eQTLs SNPs, we recommend that protein biomarker-disease association studies take into account the potential effect of common local SNPs and that pQTLs be integrated along with eQTLs to uncover disease mechanisms. Large-scale blood biomarker studies would also benefit from close attention to the ABO blood group

First-line treatment in the management of advanced renal cell carcinoma: systematic review and network meta-analysis

<div><p><b><i>Objectives:</i></b> To conduct a systematic review and network meta-analysis (NMA) to assess effectiveness of first-line treatments for advanced renal cell carcinoma (RCC).</p><p><b><i>Methods:</i></b> Database searches were conducted to identify randomized controlled trials (RCTs) reporting results for eligible treatments. A fixed-effect Bayesian NMA was conducted to assess the relative effectiveness of treatments, with progression-free survival (PFS) reported as hazard ratios (HRs) and 95% credible intervals (CrIs).</p><p><b><i>Results:</i></b> Eleven unique RCTs were suitable for inclusion in the NMA. In the base case, in terms of PFS, sunitinib was superior compared with bevacizumab + IFN-α (HR = 0.79, 95% CrI: 0.64 – 0.96), everolimus (HR = 0.70, 95% CrI: 0.56 – 0.87), sorafenib (HR = 0.56, 95% CrI: 0.40 – 0.77) and temsirolimus + bevacizumab (HR = 0.74, 95% CrI: 0.56 – 0.96). Although, the point values for the mean and median HRs were < 1.0, there was no significant difference in PFS between sunitinib and axitinib, pazopanib or tivozanib. Although sensitivity analyses impacted the results of the NMA, no treatment was significantly more efficacious than sunitinib.</p><p><b><i>Conclusion:</i></b> Results from this analysis suggest that there is no treatment superior to the current benchmark treatment, sunitinib, in the management of advanced RCC in the first-line setting.</p></div

An improved protocol for the Prins desymmetrization of cyclohexa-1,4-dienes

Improved conditions are reported for the Prins-pinacol rearrangement of cyclohexa-1,4-diene-derived acetals. The use of triflic acid gives particularly clean reaction, resulting in a mixture of regioisomers in an approximately 10:1 ratio. A tethered version of this reaction is also reported, giving a tricyclic compound with the same stereochemistry as the core of the cladiellin diterpenes

ChemInform Abstract: An Improved Protocol for the Prins Desymmetrization of Cyclohexa-1,4-dienes.

Improved conditions are reported for the Prins-pinacol rearrangement of cyclohexa-1,4-diene-derived acetals. The use of triflic acid gives particularly clean reaction, resulting in a mixture of regioisomers in an approximately 10:1 ratio. A tethered version of this reaction is also reported, giving a tricyclic compound with the same stereochemistry as the core of the cladiellin diterpenes