Background and Aim: Minimizing the polymerization shrinkage of composite resins is a critical goals in composite restorations. Many factors affect polymerization shrinkage. This study aimed to evaluate the effect of composite resin shade on polymerization shrinkage. Materials and Methods: In this in vitro study, 14 composite discs measuring 1.5×8 mm were fabricated. The samples were prepared u...

Various species of [2-14C] MVA stereospecifically labelled with tritium at C-2, C-4 and C-5 have been used to study details of carotenoid biosynthesis in a variety of preparations including chioroplasts, fruit and root slices, and fungi. Mechanisms have been proposed for the dimerization of geranylgeranyl pyrophosphate to form phytoene, for the cyclization of acyclic precursors to form aand a-c...

This communication details the Pd-catalyzed decarboxylation of selenocarbonates; use of a chiral nonracemic catalyst affords enantioenriched allyl selenides which undergo stereospecific [2,3]-sigmatropic rearrangements to form enantioenriched allylic amines and chlorides.

A stereospecific palladium-catalyzed N-vinylation of azaheterocycles with vinyl triflates is described. Cyclic and acyclic vinyl triflates along with nonnucleophilic azaheterocycles were found to be substrates for this palladium-catalyzed synthesis of N-vinyl pyrrole and indole derivatives.

This paper describes a simple route to enantiomerically enriched [2.2]paracyclophane-4-thiol via the stereospecific introduction of a chiral sulfoxide to the [2.2]paracyclophane skeleton. The first synthesis of an enantiomerically enriched planar chiral benzothiazole is also reported.

Self-assembled pseudocyclic structures consisting of two molecules of a crown-containing butadienyl dye and two Mg(2+) ions readily undergo regio- and stereospecific [2+2] photocycloaddition in MeCN to produce a single cyclobutane stereoisomer in almost quantitative yield.