Fabricating an esthetically pleasing removable partial denture while avoiding the unsightly display associated with conventional clasp assemblies presented a challenge to dentists. Among other techniques, this could be done using acetal resin clasps as simple and effective means of improving removable partial denture esthetics.1 Patients often cite lack of retention and poor esthetics as reason...

A systematic study of the oxidation of a range of terminal diols is reported, employing the oxoammonium salt 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (4-NHAc-TEMPO+ BF4-) as the oxidant. For substrates bearing a hydrocarbon chain of seven carbon atoms or more, the sole product is the dialdehyde. A series of post-oxidation reactions have been performed showing th...

Cantleyoside-dimethyl-acetal (6), was isolated from the endemic Greek plant Pterocephalus perennis subsp. perennis in addition to five other known iridoid glucosides, loganin, loganic acid, cantleyoside, secologanin, and secologanin-dimethyl-acetal. The structure of these compounds was determined by all spectroscopic means mainly by NMR and MS techniques. The above compounds as well as their ac...

M uham m ad Saeed3, M uham m ad A bbas3, Khalid M oham m ad K hanb, and Wolfgang V oelter3 a Abteilung für Physikalische Biochemie, Physiologisch-chemisches Institut der Universität Tübingen, Hoppe-Seyler-Straße-4, D-72076 Tübingen, Germany b International Center for Chemical Sciences, H. E. J. Research Institute of Chemistry, University of Karachi, Karachi-75276, Pakistan Reprint request to Pr...

13C-NMR studies have confirmed the structures of (8S)-8-hydroxyerythromycins A- and B-6,9;9,11-acetal proposed by KROWICKI and ZAMOJSKI2,3) for the products of the m-chloroperbenzoic acid oxidation of 8,9-anhydroerythromycins A- and B-6,9-hemiacetal. The preparations of (8S)-8-methylthiomethoxy- and (8S)-8-methoxyerythromycin B-6,9;9,11-acetals are described. The latter are stable in aqueous ac...

For the first time, relative distributions of optical and geometrical isomers in selected propylene glycol acetals are determined. Resolution of the four acetal isomers possible through the reaction of racemic propylene glycol (PG) with selected aldehydes is demonstrated. The four isomers are ascribed to the presence of syn and anti geometrical isomers for each optically active PG acetal enanti...

The three-dimensional spatial structure of a methylene-acetal-linked thymine dimer present in a 10 basepair (bp) sense-antisense DNA duplex was studied with a genetic algorithm designed to interpret NOE distance restraints. Trial solutions were represented by torsion angles. This means that bond angles for the dimer trial structures are kept fixed during the genetic algorithm optimization. Bond...

The investigation of RNA structure, dynamics and biological function often requires the site-specific incorporation of non-natural moieties. Here we describe the functionalization of RNA transcripts by aldehyde-hydrazine chemistry using a simple initiator nucleotide that carries an acetal-protected aldehyde function. This initiator nucleotide was efficiently incorporated into RNA, and the modif...