Alkylation of Imidazolidinone Dipeptide Derivatives: Preparation of Enantiomerically Pure Di- and Tripeptides by ‘Chirality Transfer’ via a Pivalaldehyde N,N-Acetal Center. Preliminary Communication
✍ Scribed by Robin Polt; Dieter Seebach
- Publisher
- John Wiley and Sons
- Year
- 1987
- Tongue
- German
- Weight
- 432 KB
- Volume
- 70
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Glycylglycine, glycyl-(S)-alanine, and (S)-alanylglycine esters are cyclized through pivalaldehyde imines to give dipeptide-derived 3-(benzyloxycarbonyl)-2-(~er~-butyl)-5-oxoimidazo~idine-l -acetates 1-3. These are alkylated diastereoselectively by Li-enolate formation and addition of alkyl bromides or iodides (products 4-6).
Starting from (S)-alanine and glycine, (S)-alanyl-(S)-alanine or (R)-alanyl-(R)-alanine, and (R)-alanyl-(R)-alanyl-(5')-alaninc have thus been prepared, with the (tert-butyl)-substituted N,N-acetal center playing the role of a pivot or lever for diastereoselective formation of new stereogenic centers under kinetic or thermodynamic control. ') Recipient of a United States Nutional Research Service Award (GMI 1371-01). The Swiss Nutional Scicnce Foundation has partially financed the stay of R. P. in Zurich (Project No. 2.253-0.84), 1986/87.