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Martin Michels

Publications and source records attributed to Martin Michels.

4 recordsLinked to original sources
PubMed2005

Efficient regioselective synthesis of 6-amino-5-benzoyl-1-substituted 2(1H)-pyridinones.

[Reaction: see text]. A regioselective and efficient approach toward 6-amino-5-benzoyl-1-substituted 2(1H)-pyridinones by reaction of acyclic ketene aminals with propiolic acid ester was developed. The effect of the solvent and temperature on the regioselectivity of the reaction and the compatibility of the target compounds to functional group manipulations was examined. Substrates with an ortho substituent build atropisomers due to the restricted rotation around the C-N bond. The enantiomers were separated, and the barrier of rotation was determined experimentally. Quantum chemical calculations allowed a ranking of the barrier heights, and a new mechanism of rotation by deformation of the central pyridinone moiety is proposed.

Models, Chemical↗
PubMed2005

[Malignant melanoma -- a medical students' viewpoint].

Malignant melanoma is a primarily cutaneous melanocytic tumour with increasing incidence responsible for 90 % of skin cancer mortality. Genetic predisposition has been identified as the most important risk factor, while UV is second in importance and can be avoided. New diagnostic methods include sentinel lymph node biopsy and the detection of tumour markers in blood. Furthermore, malignant melanoma shows an extraordinary resistance to therapy; at present the only cure lies in early excision of the primary tumour. Thus early recognition is of utmost importance. Experimental approaches, such as dendritic cell vaccination, have shown some effectiveness which must be confirmed in multicenter, randomised trials.

Adult↗
PubMed2003

Spiroconjugation in spirodicorrolato-dinickel(II).

In the present work the effect of spiroconjugation on the electronic spectrum of the recently synthesized metal complex hexadecaethylspirodicorrolato-dinickel(II) (5) (the corrole units in 5 are isoforms) is investigated. To have a suitable reference compound at our disposal, tetraethylhexamethylisocorrolato nickel(II) (7) has been prepared. On comparing the electronic spectra of this reference compound and the spiro-complex, bathochromic shifts of all absorption bands in the NIR/Vis-region are observed for the latter as well as marked changes in the spectral intensities. A detailed analysis of the spectra supported by semiempirical calculations reveals that at least part of the observed changes can be unambiguously attributed to the spiro effect. This effect is further affirmed by electrochemically measured redox potentials.

Journal Article↗