Christiane Strehler

Ring closing metathesis as an efficient approach to branched cyclitols and aminocyclitols: a short synthesis of valiolamine

Abstract Ring closing metathesis of sugar-derived 1,6 dienes is the key step for the construction of highly functionnalized cyclohexenes, precursors of branched cyclitols and aminocyclitols. The method has been used for a short synthesis of valiolamine.

Determination of nicotine in allergenic extracts of tobacco leaf by high-performance liquid chromatography.

A high-performance liquid chromatographic (HPLC) system has been developed for the determination of nicotine and cotinine in allergenic extracts of tobacco leaf. This analysis showed eight allergenic extracts of tobacco (leaf and Mix) to have markedly different nicotine patterns. Cotinine, a photodegradation product of nicotine, was not detected.

De Novo asymmetric synthesis of two 5-amino-5,6-dideoxy-D-allose derivatives

Abstract Diels-Alder cycloaddition of sorbic aldehyde derivative 9 and of sorbic acid 10 with the chiral chloro-nitroso dienophile 7 led with excellent regio- and diastereoselectivity to the chiral cycloadducts 11a and 12 , respectively. Catalytic osmylation of their Bzl-derivatives 11b and 13b , followed by reductive cleavage of the NO bonds, gave ultimately the chiral aminoallose derivatives D-5 and D-6 which are potential glycosidase inhibitors.

A simple asymmetric synthesis of 2-substituted 2,3-dihydro-4-pyridones

A pronounced asymmetric induction (d.e. = 95 %) was observed during methylation of pyridinium salt 7 with MeMgI which led ultimately to (2R) 2-methyl-2,3-dihydro-4-pyridone 9. This result is best explained by assuming chelate-control during the asymmetric alkylation step.

Photoconversion de [1-H] diazepines-1,2 substituees.

Resume Experimental evidence is given which shows that the two chlorodiazepines 2 and 3 are formed simultaneously by a photoinduced ring-enlargement of the parent N-iminopyridinium ylide 1 , and that the ensuing [1,7] sigmatropic shift of the benzoyl group of 2 and 3 is but a minor process; the major process of the second photochemical step being the formation of the bicyclic isomers 4 and 5 .