Angelika Thurner

Competition and co-operation between ortho directing groups and activating agents: Regioselective metallation of 1-(methoxyphenyl)pyrroles

Abstract The role of di- and tri-dentate tertiary amine type ligands was studied in regioselective lithiation reactions of 1-(methoxyphenyl)pyrroles with butyllithium (LIC). Clean α-metallation of the pyrrole ring occured when N,N,N′,N′,N″-pentamethyldiethylenetriamine (PMDTA) was used while the benzene ring was lithiated ortho position to the methoxy group in the presence of N,N,N′,N′-tetramethylethylenediamine (TMEDA).

Useful base promoted elaborations of oxiranyl ethers

Abstract Functionalized oxiranyl ethers can be regio- and stereoselectively converted into hydroxy oxetanes or cis -diols by treatment with organometallic bases. These two rearrangements can be conveniently carried out either using different reaction conditions starting from the oxirane or in two consecutive steps from the oxirane via the oxetane.

A new base promoted rearrangement of (E)-1-benzyloxy-2,3-epoxyalkanes

Abstract ( E )-1-benzyloxy-2,3-epoxyalkanes ( 4 ) underwent stereoselective rearrangement in the presence of LIDAKOR reagent and large excess of butyllithium producing ( Z )-alkendiols (7) at ambident temperature. The same reaction serves anti oxetanes (6) at −75 °C which can also rearrange to 7 when the temperature arises.

Resolution and enantioselective rearrangements of amino group-containing oxiranyl ethers

Abstract Resolution protocols for 2-benzyloxymethyl-3-diethylaminomethyloxirane and 2-benzyloxymethyl-3-piperidinomethyloxirane have been developed. In the presence of organometallic bases enantioselective rearrangement of the newly separated oxirane enantiomers provides chiral oxetanes or cis -but-2-ene-1,4-diol derivatives without any racemization. The stereochemistry of the oxetanes was investigated by 1 H NMR and molecular modeling. A novel method using an atropisomeric dicarboxylic acid as a chiral solvating agent in 1 H NMR for the determination of the enantiomeric excess of the products is also reported.

Kinetic resolution of racemic alkoxy oxiranes by chiral lithium amides

Abstract The isomerization of alkoxy oxiranes with chiral lithium amides has been carefully investigated with the aim of finding an enantioselective approach to hydroxy enolethers, a class of compounds which can be used for further synthetic elaborations.

Efficient methods for optional metalation of 1-(methylphenyl)pyrroles in α or benzylic positions

Novel, selective metalation methods have been described for optional functionalisation of 1-(methylphenyl)pyrroles in α or benzylic positions and an efficient way for dilithiation of the model compounds has also been reported.

Organometallic approach to the functionalization of alkyl groups containing 1-phenylpyrroles

Abstract Novel regioselective methods have been developed for the mono‐ and difunctionalization of alkyl groups containing 1‐phenylpyrroles using different organometallic reagents. Tailoring the reagents and conditions allowed us to prepare several new mono‐ and rotationally restricted dicarboxylic acid derivatives of 1‐(alkylphenyl)pyrroles in good yields.

N, N, N', N', N -PENTAMETHYLDIPROPYLENETRIAMINE (PMDPTA) : A VERSATILE AUXILIARY FOR SITE SELECTIVE LITHIATION REACTIONS

Abstract Efficient lithiation processes were developed with PMDPTA, a tridentate ligand of butyllithium reagent for site selective metallation of aromatic and heteroaromatic compounds.

Regioselective Metallation of Propylbenzene with Superbase: A Convenient Route to Stilbene Derivatives

The benzylic metallation of propylbenzene has been elaborated with LIC–KOR superbase; the method has been applied in a new synthesis of stilbene derivatives.

Novel methods for the stereoselective synthesis of oxetane, azetidine and pyrrolidine derivatives

Novel, superbase promoted stereoselective rearrangement reactions of chiral oxirane derivatives provided chiral oxetane and azetidine derivatives. An optically active 3,4-disubstituted pyrrolidine was synthetised via catalytic hydrogenolysis of an oxetane derivative followed by ring closure of the formed optically active aminoalcohol.