Heat-cured poly(methyl methacrylate) resin incorporated with different food preservatives as an anti-microbial denture base material.

Background/purpose: The colonization of microorganisms onto denture bases is one common problem that can contribute to oral diseases. Herein, three food preservatives, including zinc oxide, potassium sorbate, and sodium metabisulfite were introduced as anti-microbial additives into a heat-polymerized poly(methyl methacrylate) (PMMA).

Materials And Methods: Relative microbial reductions of the modified PMMA resins against , , and were evaluated.

Intramolecular Diels-Alder reactions using chiral ruthenium Lewis acids and application in the total synthesis of ent-ledol.

One-point binding chiral ruthenium Lewis acids incorporating the C(2)-symmetric electron-poor bidentate phosphinite ligand BIPHOP-F and a Cp or an indenyl 'roof' can efficiently catalyze asymmetric intramolecular Diels-Alder reactions of trienes to form bicyclic adducts with good to excellent asymmetric induction. This reaction forms the key step in a total synthesis of ent-ledol in 96% ee. The synthesis also helps to clarify the stereochemical assignment of ledol and inconsistencies in the measured optical rotation.

Asymmetric intramolecular Diels-Alder reactions of trienals catalyzed by chiral ruthenium Lewis acids.

Chiral single-point binding ruthenium Lewis acid catalysts [Ru(acetone)((S,S)-BIPHOP-F)(Cp)][SbF6] ((S,S)-1a) and [Ru(acetone)((S,S)-BIPHOP-F)(indenyl)][SbF6] ((S,S)-1b) efficiently catalyze intramolecular Diels-Alder (IMDA) reactions of trienals under mild conditions to afford the endo cycloaddition products as the major products in good yields with high diastereo- and enantioselectivities.

Chiral ruthenium Lewis acid catalyzed intramolecular Diels-Alder reactions.

Single point binding ruthenium Lewis acid catalysts [Ru(acetone)(S,S)-BIPHOP-F)Cp][SbF(6)] ((S,S)-1b) and [Ru(acetone)(S,S)-BIPHOP-F)(indenyl)][SbF(6)] ((S,S)-1c) efficiently catalyze intramolecular Diels-Alder (IMDA) reactions under mild conditions to afford the endo cycloaddition products as the major product in excellent yields with high diastereo- and enantioselectivities.

Morita-Baylis-Hillman reaction of masked 5-alkylidene-2-cyclopentenones: general entry to 5-alkylidene-2-(hydroxyalkyl)- 2-cyclopentenones.

The reaction of masked 5-alkylidene-2-cyclopentenones with aldehydes catalyzed by tributylphosphine in the presence of phenol provided the corresponding Morita-Baylis-Hillman adducts, which were subjected to flash vacuum pyrolysis to afford 5-alkylidene-2-(hydroxyalkyl)-2-cyclopentenones.