ABSTRACT
Palladium(II)-catalyzed macrocyclizations of bis(vinylboronate ester) compounds are demonstrated to provide a strategically efficient approach to transannular Diels-Alder reaction substrates. In several systems reported, the macrocycle is preorganized such that cycloaddition at room temperature occurs concomitantly with cyclization. Numerous advantages over palladium(0)-catalyzed cross-coupling approaches are demonstrated.
Subject(s)
Heterocyclic Compounds, 3-Ring/chemical synthesis , Palladium/chemistry , Polycyclic Compounds/chemical synthesis , Boron Compounds/chemistry , Catalysis , Cyclization , Heterocyclic Compounds, 3-Ring/chemistry , Molecular Structure , Polycyclic Compounds/chemistryABSTRACT
UNLABELLED: The art and craft of recording intra-oral anatomy successfully with dental impressions relies on the interaction of three critical factors--the 'golden triangle of impression-taking': an appreciation of the anatomical features to be recorded, the material used to take the impression and the clinical handling/operative technique applied. This paper aims to discuss the three factors and their inter-relationships, detailing clinical tips for successful, reproducible and consistent outcomes. CLINICAL RELEVANCE: Obtaining accurate dental impressions is the key to success in a wide range of clinical restorative procedures. This paper offers clinical advice to practitioners to plan and then take predictable, good quality impressions for their restorative cases.
Subject(s)
Dental Impression Materials , Dental Impression Technique , Anatomic Landmarks , Computer-Aided Design , Crowns , Dental Impression Technique/instrumentation , Dental Prosthesis Design , Denture, Partial, Fixed , Gagging/prevention & control , Humans , Inlays , Models, DentalABSTRACT
As a complement to Pd(0)-catalyzed cyclizations, seven Pd(II)-catalyzed cyclization strategies are reported. α,ω-Diynes are selectively hydroborated to bis(boronate esters), which cyclize under Pd(II)-catalysis producing a diverse array of small, medium, and macrocyclic polyenes with controlled E,E, Z,Z, or E,Z stereochemistry. Various functional groups are tolerated including aryl bromides, and applications are illustrated.
Subject(s)
Diynes/chemistry , Palladium/chemistry , Polyenes/chemical synthesis , Catalysis , Cyclization , Esters , Molecular Structure , Polyenes/chemistry , Stereoisomerism , Vinyl Compounds/chemistryABSTRACT
Since the 1970s when the implantable cardioverter defibrillator (ICD) was developed, multiple clinical trials have documented survival benefits in certain high-risk subsets of heart failure patients. Over the past decade, cardiac resynchronization therapy (CRT) emerged as an important therapy in carefully selected patients with ongoing symptoms despite optimized pharmacological therapy. ICDs should be considered first-line therapy for survivors of life-threatening ventricular arrhythmic events. Subsets of patients with both ischemic and nonischemic dilated cardiomyopathy appear to have a survival benefit from primary ICD therapy. CRT has resulted in substantial symptomatic improvement and survival benefits in a subgroup of chronic heart failure patients. CRT should be considered in heart failure patients undergoing ICD implantation who have evidence of ventricular dyssynchrony.
