On the reaction of 1-oxa-4-thiaspiro [4.5] decan-7-one with PhLi. A reinvestigation

Two diastereomeric alcohols are formed from the reaction of 1-oxa-4-thiaspiro[4.5]decan-7-one with PhLi as against the single diastereomer reported earlier. The diastereoselectivity achieved from PhMgBr is significantly higher than with PhLi. The use of Et<SUB>2</SUB>O/hexane=2:1 as the solvent for the reaction with PhMgBr offered the highest (14:1) diastereocontrol

Polydipyrrole- and polydicarbazole-nanorods as new nanosized supports for DNA hybridization

Novel functional polydipyrrole- and polydicarbazole nanorods have been AAO template-synthesized from COOHdipyrrole/- dicarbazole monomers using Vapor Deposition and Liquid Phase Polymerizations (VDP and LPP). They were tested as insoluble supports for covalent DNA attachment and hybridization.This work has been partly funded under both Vth [CHEMAG (nu GRD2-2000-30122)] and VIth [NACBO (nu NMP3-2004- 500802-2)] Framework European projects. It has also been supported by the Brain-Korea 21 Program (Korea Ministry of Education), and the Hyperstructured Organic Materials Research Center of the Seoul National University

Heteroatom influence on the π-facial selectivity of Diels-Alder cycloadditions to 1-Oxa-4-thia-6-vinylspiro[4.5]dec-6-ene, 3-methoxy-3-methyl-2-vinylcyclohexene, and 3-methoxy-2-vinylcyclohexene

The facial selectivities of the Diels-Alder cycloadditions of several dienophiles to the title substrates were studied. The observed selectivities are interpreted as a consequence of the relative steric interactions offered by the substituents. The addition of dimethylacetylene dicarboxylate (DMAD) is influenced by the electrostatic repulsion arising from the interaction of an electron pair orbital on the acetal oxygen and the orthogonal p-orbital of the acetylene unit in DMAD in the syn-to-oxygen addition of the latter. This repulsion is offset on coordination of Li<SUP>+</SUP> to the said oxygen electron pair orbital, and the addition thus proceeds syn to oxygen. The enhanced and accelerated syn-to-oxygen addition in lithium perchlorate in nitromethane is interpreted as a consequence of the coordination of Li<SUP>+</SUP> to both the acetal oxygen and a heteroatom in the dienophile that brings them in close proximity to facilitate a reaction. The Li<SUP>+</SUP>-oxygen combination, however, also exerts some steric effect that results in reduced syn-to-oxygen addition of dienophiles having large substituents such as N-phenylmaleimide

New magnetically responsive polydicarbazole-magnetite nanoparticles.

Magnetically responsive COOH-polydicarbazole-magnetite nanocomposites have been prepared by chemical oxidation of three COOH-dicarbazole monomers and - in the presence of magnetite nanoparticles. These functionalized nanoparticles have been tested for DNA hybridization experiments

Magnetically responsive carboxylated magnetite-polydipyrrole/polydicarbazole nanocomposites of core-shell morphology. Preparation, characterization, and use in DNA hybridization

Novel bis-heterocyclic mono- and dicarboxylated dipyrrole and dicarbazole monomers have been synthesized in a modular manner. Their oxidative polymerization around magnetite nanosized particles has been investigated and optimized toward new magnetic magnetite-polydipyrrole/polydicarbazole nanocomposites (NCs) of a core-shell morphology. These NCs were thoroughly characterized by FT-IR, TGA (Thermal Gravimetric Analysis), low- and high-resolution TEM/HR-TEM microscopies, and Mossbauer spectroscopy along with magnetization studies. Exploiting the versatile COOH chemistry (activation by water-soluble diimides) introduced by the polymeric shell, DNA hybridization experiments have been conducted onto NC surfaces using an efficient blue-colored HRP-based enzymatic screening biological system. Highly parallel NC-supported DNA hybridization experimentations revealed that these NCs presented an interesting potential for DNA-based diagnostic applications