Michał Malik

Synthesis of Polyhydroxylated Quinolizidines and Azaspiro[4.5]decanes from d-Xylose

The synthesis of novel polyhydroxylated quinolizidines and azaspiro[4.5]decanes is reported. A key step of this transformation involved an addition of allylmagnesium bromide to an ω-bromonitrile derived from D-xylose followed by an intramolecular displacement of a bromide. The resulting cyclic imine was treated either with allylmagnesium bromide or with NaBH4, to provide 2,2-diallyl- or 2-allylpiperidine, respectively. The desired bicyclic framework was constructed via a ring-closing metathesis reaction. The Ru catalysts were reused in the following syn-dihydroxylation step.

Carboxybenzyl group as an o-nucleophile in the C-H allylic oxidation: total synthesis of (-)-castanospermine.

The first palladium-mediated C-H allylic oxidation with a Cbz group acting as an O-nucleophile is reported. It was found that this transformation is promoted by rare-earth metal triflates: Yb(OTf)(3) or Sc(OTf)(3). A possible catalytic cycle is proposed. This reaction was applied in the synthesis of a d-xylose derived oxazolidinon, a versatile intermediate used further in the stereoselective synthesis of unnatural (-)-castanospermine. Cyclization of the key intermediate with PhSeBr afforded the desired bicyclic scaffold. In an alternative route, hydroboration/oxidation followed by DPPA-mediated cyclization was used.

Synthesis of polyhydroxylated decalins via two consecutive one-pot reactions: 1,4-addition/aldol reaction followed by RCM/syn-dihydroxylation

Synthesis of novel polyhydroxylated derivatives of decalin is described. The presented methodology consists in a one-pot copper-catalyzed 1,4-addition of vinylmagnesium bromide to sugar-derived cyclohexenone, followed by an aldol reaction with a derivative of but-3-enal. The obtained diene is then subjected to an assisted tandem catalytic sequence: ring-closing metathesis with the subsequent reuse of the Ru-catalyst in the syn-dihydroxylation. The stereochemical outcome of these reactions is discussed.

Recent advances in the synthesis of imino sugars. An insight into the cascade addition of Grignard reagents to halonitriles/cyclization

This review is focused on the recent advances in the synthesis of imino sugars. It is divided into the following sections: SN2 cyclizations, reactions of cyclic imines, reactions of cyclic nitrones, and ring-closing metathesis. In a separate category, a cascade addition of Grignard reagents to halonitriles followed by the SN2-type cyclization is discussed – a rarely used, but convenient approach to the synthesis of five- and six-membered heterocycles containing an endocyclic nitrogen atom.