Martin H. Fechter

Novel access to chiral 1,1′-disubstituted ferrocene derivatives via double stereoselective cyanohydrin synthesis exploiting the hydroxynitrile lyase from Hevea brasiliensis

Abstract A novel route to chiral ferrocene derivatives involving the application of hydroxynitrile lyase from Hevea brasiliensis has been developed. The method allows the conversion of formylferrocene 1 and 1,1′-diformylferrocene 2 into their corresponding chiral cyanohydrins. ( R )-(Cyanohydroxymethyl)ferrocene 3 and ( R , R )-1,1′-bis(cyanohydroxymethyl)ferrocene 4 were obtained in high yield and stereochemical purity using this method. The full structural characterisation of the latter including the determination of diastereomeric purity and the assignment of the absolute configuration is disclosed.

1-DEOXY-D-XYLULOSE SYNTHESIZED FROM THE (S)-CYANOHYDRIN OF ACROLEIN

The biocatalytic transformation of acrolein into (S)-2-hydroxybut-3-enenitrile using the (S)-hydroxynitrile lyase from Hevea brasiliensis followed by Grignard C-elongation, asymmetric epoxidation and nucleophilic ring-opening afforded 1-deoxy-D-xylulose (1) in 47% overall yield.

Synthesis of four diastereomeric octofuranoses from d-glucofuranurono-6,3-lactone via Grignard reactions

Abstract Reduction of 5- O-tert -butyldimethylsilyl-1,2- O -isopropylidene-α- d -gluco- ( 2 ) -β- l -idofuranurono-6,3-lactone ( 3 ) with diisobutylaluminum hydride (DIBAL-H) to the respective hemiacetal at C-6, followed by reaction with vinylmagnesium bromide in either ether or tetrahydrofuran, gives the corresponding diastereomeric pairs of 7,8-dideoxyoct-7-eno-1,4-furanoses. The configurations of the products at C-6 were determined after oxidative cleavage of the terminal double bond and reduction of the aldehyde by conversion of the resulting heptoses into the known corresponding per- O -acetylated heptitols.

A Sucrose-Based Approach to Enantiomerically Pure Glycerol Derivatives

Abstract Taking advantage of the same configuration present at C-5 and C-5′ in sucrose, 6,6′-diprotected sucrose derivatives were transformed into enantiomerically pure glycerol derivatives. This was achieved by oxidative ring cleavage of both the glucopyranosyl ring as well as the fructofuranosyl moiety followed by reduction of the resulting tetraaldehyde and subsequent per-O-protection of the resulting pentahydroxy compound. The obtained intermediate was hydrolysed under acidic conditions to furnish two equivalents of partially protected chiral glycerol derivative per molecule of starting material. The efficiencies of sodium metaperiodate and lead tetraacetate as oxidizing agents were compared and the side reactions observed in these procedures were investigated.