Michela Valacchi

Base-promoted elaboration of aziridines

The base-promoted isomerization of aziridines to allyl amines is still an almost unknown reaction. However, the use of superbasic reagents has shown to be able to promote a regio- and stereoselective conversion of monocyclic and bicyclic sulfonyl aziridines. Moreover, the use of alkoxy substituted aziridines opens new routes to non-natural α- and β-amino acids.

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 stereoselective approach to the synthesis of aminoalcohols

Abstract Amino alkoxy oxiranes have been isomerized to stereochemically pure amino alcohols, useful precursors for dipeptides isosteres, by treatment with the superbasic mixture butyllithium/ diisopropylamine/ potassium tert-butoxide.

A stereoselective approach to the synthesis of γ-silylated amino acids

The synthesis of enantiomerically enriched silicon containing amino acids is described. Silylcupration of 2,2-dimethyl-3-(tert-butoxycarbonyl)-4-ethynyloxazolidine, easily derived from serine aldehyde, afforded regio- and stereoselectively γ-silylated ethenyloxazolidines of (E)-geometry as useful precursors of saturated and unsaturated γ-silylated amino acids.

Base promoted isomerization of aziridinyl ethers: a new access to α- and β-amino acidsElectronic supplementary information (ESI) available: experimental procedures and NMR data. See http://www.rsc.org/suppdata/cc/b2/b200708h/.

Aziridinyl ethers are selectively and easily converted to either amino vinyl ethers or alkoxy allylamines by treatment with mixed metal bases (superbases).

New unsaturated amino acids containing an allylsilane moiety on the lateral chain

New enantiomerically enriched polyfunctionalized allylsilanes have been obtained from the synthetic elaboration of naturally occurring serine. In particular, an oxazolidine bearing an allylsilane framework on the lateral chain proved to be a suitable precursor for the corresponding silylated vinyl glycine derivatives.

Synthesis of non-racemic β-branched α-(aminoalkyl)-acrylates from naturally occurring amino acids

Abstract Non-racemic Boc-protected γ-stannylated-α-(aminoalkyl)acrylates of ( Z ) geometry have been selectively obtained by addition of stannylcuprate onto propargylamines, followed by reaction with carbon dioxide. Stille coupling has been investigated and a small library of six new β-branched-α-(aminoalkyl)acrylates obtained. These compounds are useful intermediates for the synthesis of new enantiomerically enriched β-amino acids.