Polydopamine (PDA) is easily available by oxidation of dopamine and is widely used for persistent coatings of various materials. It is hitherto considered to be inert in many interesting biomedical and other applications. Results presented here, reveal an unexpected behavior of polydopamine as an organocatalyst in direct aldol reactions under mild conditions. Evidence was found for dual catalysis making use of amino and phenolic hydroxy groups found in PDA. Thus scientists must be aware that PDA is not an innocent polymer and can cause unwanted side effects in important applications, such as in biomedicine or as supports in catalysis.

Novel magnetically tagged organocatalysts have been developed based on core-shell nanoparticles consisting of magnetite cores and polyacrylate shells containing 4-hydroxyproline moieties. These catalysts allow the performance of direct asymmetric aldol reactions of aromatic aldehydes with ketones in the presence of benzoic acid providing high yields and ees. Straightforward magnetic separation and recycling of a catalyst for up to 9 runs is possible without a significant loss of efficiency.

Magnetic nanoparticles (NP) have found various important applications in nanotechnology and nanomedicine, because they can be manipulated by external magnetic field and can be functionalized on their surface. Although a variety of magnetic core shell NP are known present research focuses on new NP with better properties (reduced toxicity, high colloidal and chemical stability, wide scope of application) and more straightforward and reproducible syntheses. In this work, we report the synthesis of azido-functionalized polypyrrole (PPy)-based superparamagnetic core shell NP by surface initiated polymerization wherein miniemulsion technique have been applied in this field for the first time. The new NP are attractive for biomedical applications because the PPy is biocompatible, the shell can easily be functionalized by Cu-catalyzed click-reaction as shown by the introduction of biotin and the material exhibits superparamagnetic behavior. The surface initiated polymerization is carried out at new magnetite NP, which are stabilized by pyrrol-containing fatty acids. Although these starting NP lack a polymer shell, they show a remarkable stability and thus have the potential for further functionalization. The magnetic NP are characterized by various methods such as FTIR, X-ray photoelectron spectroscopy, magnetic measurements, thermal gravimetric analysis, and dynamic light scattering. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

A straightforward synthesis of 2′-functionalized uridines was developed based on a Cu-catalyzed cycloaddition of 2′-azido-2′-deoxyuridine and functionalized alkynes. The functions comprise biochemically important groups such as lipids, a fluorescent marker (Cy5 analogue), pentaacetylglucose, lysine and biotin, and are linked to the 2′-position of uridine by a 1,2,3-triazole ring. A number of NMR spectroscopic investigations revealed that the lipidated 2′-triazolyl-2′-deoxyuridines anchor themselves in the phospholipid membranes without affecting the molecular order in the double layers; the polar moieties – uracil, ribose and triazole – are located in the lipid/water interface of the membrane.

A remarkable improvement of both the chemical yield (from 6% to 82%) and the enantiomeric excess (up to >99%), of (S)-proline catalyzed direct aldol reactions of a wide range of aldehydes with acetone was found when hexasubstituted or pentasubstituted guanidinium salts were added as ionic liquids. Effects of temperature, amount of proline and the type of guandidinium salts on the outcome of the reaction were investigated.

Various new nucleosides bearing one or two lipophilic groups at the 2′-position have been synthesized. The lipophilic substituents were attached to a 2′-hydroxy, 2′-amino, or 2′-thio function. These lipophilic nucleosides anchor in large unilamellar POPC vesicles serving as phospholipid membrane models. The insertion of these molecules into the membranes was investigated by NMR techniques. For comparison, nucleosides with two or three lipophilic groups at the 2′-, 3′-, or 5′-positions have also been studied.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Reissert compounds 2 derived from isoquinoline, chloroformates and TMS-cyanide were alkylated in position 1. The resulting alkylation products 3 as well as the precursors 2 reacted with Grignard reagents affording imidazoisoquinolines 4, 5, 7 and 8 by addition to the cyano group and Grignard reduction or by twofold addition to the cyano group, respectively. In both cases the alcohol of the 2-alkoxycarbonyl moiety was eliminated by attack of the N-atom at the carbonyl carbon atom. Under acid conditions, 1-benzylated Reissert compound 3h cyclised by attack of the resulting N-acyliminium C-atom at the o-position of the benzyl ring to form tetracyclic 1,3-bridged tetrahydroisoquinolines 10 and 11. Bromocyclisation of 1-allyl-2-menthyloxycarbonyl-substituted Reissert compounds 3b, c led to tricyclic dibromo products 12, in which the menthol moiety was split off and addition to the enamine double bond occurred. A 2-menthyloxycarbonyl group in Reissert compounds 2a and 3 failed to exert an asymmetric induction in all cases.