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2 Polish Journal of Chemistry

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Asymmetric Synthesis of Multi-substituted Indolizidines by Intramolecular Addition of Allylsilane to Chiral 2,3-Dihydro-4-pyridones

Furman B., Frelek J., Dziedzic M., Kamińska A.

Polish Journal of Chemistry

2005

Vol. 79 / nr 12

1919-1928

A short and synthetically attractive asymmetric synthesis of substituted indolizidines is described. The discovered reaction sequence consists of the asymmetric aza-Diels-Alder reaction of aldimines with Danishefsky's diene and the intramolecular Hosomi-Sakurai allylation. The absolute configuration of cycloadducts was established by CD-spectroscopy

A,B-unsaturated sugar D-lactones : Preparation and conjugate addition of hydroxylamines and hydrazines

Panfil I., Mostowicz D., Chmielewski M.

Polish Journal of Chemistry

1999

vol. 73 nr 7

1099-1110

Oxidation of 2,3-unsaturated glycosides with hydrogen peroxide in the presence of molybdenum trioxide as catalyst provides corresponding A, B-unsaturated sugar d-lactones via the anomeric hydroperoxide stage. Conjugate addition of N-substituted hydroxylamines and hydrazines to these d-enealdonolactones proceeds anti to the C-6 carbon atom. The adducts undergo rearrangement consisting in opening of the lactone ring and formation of 3-substitued isoxazolidin-5-one or 5-substitued pyrazolidin-3-one, respectively. Introduction of a leaving group to the polyol side chain of both heterocycles induces further rearrangements.