- Preparation of β2-amino acid derivatives (β2hThr, β2hTrp, β2hMet, β2hPro, β2hLys, pyrrolidine-3-carboxylic acid) by using DIOZ as chiral auxiliary
-
The title compounds were prepared from valine-derived N-acylated oxazolidin-2-ones, 1-3, 7, 9, by highly diastereoselective (≥ 90%) Mannich reaction (→ 4-6; Scheme 1) or aldol addition (→ 8 and 10; Scheme 2) of the corresponding Ti- or B-enolates as the key step. The superiority of the '5,5-diphenyl-4-isopropyl-1,3-oxazolidin-2-one' (DIOZ) was demonstrated, once more, in these reactions and in subsequent transformations leading to various t-Bu-, Boc-, Fmoc-, and Cbz-protected β2-homoamino acid derivatives 11-23 (Schemes 3-6). The use of ω-bromo-acyl-oxazolidinones 1-3 as starting materials turned out to open access to a variety of enantiomerically pure trifunctional and cyclic carboxylic-acid derivatives.
- Gessier, Francois,Schaeffer, Laurent,Kimmerlin, Thierry,Floegel, Oliver,Seebach, Dieter
-
p. 2235 - 2249
(2007/10/03)
-
