Catalytic Transformations of Alkynes via Ruthenium Vinylidene and Allenylidene Intermediates

NOTICE: This is the peer reviewed version of the following book chapter: Varela J. A., González-Rodríguez C., Saá C. (2014). Catalytic Transformations of Alkynes via Ruthenium Vinylidene and Allenylidene Intermediates. In: Dixneuf P., Bruneau C. (eds) Ruthenium in Catalysis. Topics in Organometallic Chemistry, vol 48, pp. 237-287. Springer, Cham. [doi: 10.1007/3418_2014_81]. This article may be used for non-commercial purposes in accordance with Springer Verlag Terms and Conditions for self-archiving.Vinylidenes are high-energy tautomers of terminal alkynes and they can be stabilized by coordination with transition metals. The resulting metal-vinylidene species have interesting chemical properties that make their reactivity different to that of the free and metal π-coordinated alkynes: the carbon α to the metal is electrophilic whereas the β carbon is nucleophilic. Ruthenium is one of the most commonly used transition metals to stabilize vinylidenes and the resulting species can undergo a range of useful transformations. The most remarkable transformations are the regioselective anti-Markovnikov addition of different nucleophiles to catalytic ruthenium vinylidenes and the participation of the π system of catalytic ruthenium vinylidenes in pericyclic reactions. Ruthenium vinylidenes have also been employed as precatalysts in ring closing metathesis (RCM) or ring opening metathesis polymerization (ROMP). Allenylidenes could be considered as divalent radicals derived from allenes. In a similar way to vinylidenes, allenylidenes can be stabilized by coordination with transition metals and again ruthenium is one of the most widely used metals. Metalallenylidene complexes can be easily obtained from terminal propargylic alcohols by dehydration of the initially formed metal-hydroxyvinylidenes, in which the reactivity of these metal complexes is based on the electrophilic nature of Cα and Cγ, while Cβ is nucleophilic. Catalytic processes based on nucleophilic additions and pericyclic reactions involving the π system of ruthenium allenylidenes afford interesting new structures with high selectivity and atom economy

Early treatment with tolvaptan improves diuretic response in acute heart failure with renal dysfunction

Background: Poor response to diuretics is associated with worse prognosis in patients with acute heart failure (AHF). We hypothesized that treatment with tolvaptan improves diuretic response in patients with AHF. Methods: We performed a secondary analysis of the AQUAMARINE open-label randomized study in which a total of 217 AHF patients with renal impairment (eGFR <60 mL/min/1.73 m(2)) were randomized to either tolvaptan or conventional treatment. We evaluated diuretic response to 40 mg furosemide or its equivalent based on two different parameters: change in body weight and net fluid loss within 48 h. Results: The mean time from patient presentation to randomization was 2.9 h. Patients with a better diuretic response showed greater relief of dyspnea and less worsening of renal function. Tolvaptan patients showed a significantly better diuretic response measured by diuretic response based both body weight [-1.16 (IQR -3.00 to -0.57) kg/40 mg vs. -0.51 (IQR -1.13 to -0.20) kg/40 mg; P <0.001] and net fluid loss [ 2125.0 (IQR 1370.0-3856.3) mL/40 mg vs. 1296.3 (IQR 725.2-1726.5) mL/40 mg; P <0.001]. Higher diastolic blood pressure and use of tolvaptan were independent predictors of a better diuretic response. Conclusions: Better diuretic response was associated with greater dyspnea relief and less WRF. Early treatment with tolvaptan significantly improved diuretic response in AHF patients with renal dysfunction