1. New sugars from antigenic lipopolysaccharides of bacteria: identification and synthesis of 3-O-[(R)-1-carboxyethyl]-L-rhamnose, an acidic component of Shigella dysenteriae type 5 lipopolysaccharide
N K Kochetkov, B A Dmitriev, L V Backinowsky Carbohydr Res. 1976 Nov;51(2):229-37. doi: 10.1016/s0008-6215(00)83330-3.
A new acidic sugar, 3-O-[(R)-1-carboxyethyl]-L-rhamnose (1), has been identified as a constituent of the O-antigenic lipopolysaccharide of Sh. dysenteriae type 5. The structure of 1 has been established by physico-chemical methods and by synthesis. Alkylation of methyl 2,5-di-O-benzyl-alpha-L-rhamnofuranoside (6) with (S)- or (R)-2-chloropropionic acids, followed by removal of the protecting groups, afforded 3-O-[(R)-1-carboxyethyl]-L-rhamnose (9) and 3-O-[(S)-1-carboxyethyl]-L-rhamnose (10), respectively. The properties of 1 coincide with those of 9.
2. Stereoselective synthesis of Psi[CH(2)O] pseudodipeptides and conformational analysis of a PhePsi[CH(2)O]Ala containing analogue of the drug desmopressin
Mattias Hedenström, Lotta Holm, ZhongQing Yuan, Hans Emtenäs, Jan Kihlberg Bioorg Med Chem Lett. 2002 Mar 25;12(6):841-4. doi: 10.1016/s0960-894x(02)00016-1.
A method for synthesis of XaaPsi[CH(2)O]Ala/Gly pseudodipeptides in good yields and excellent diastereoselectivity from azido alcohols and (R)-2-chloropropionic acid or tert-butyl bromoacetate has been developed. Insertion of one of the pseudodipeptide building blocks in the peptide drug desmopressin revealed that methylene ether isosteres may have only a minor influence on the secondary structure of peptides.
