62138-50-5Relevant articles and documents
One-handed helical screw direction of homopeptide foldamer exclusively induced by cyclic α-amino acid side-chain chiral centers
Demizu, Yosuke,Doi, Mitsunobu,Kurihara, Masaaki,Maruyama, Tokumi,Suemune, Hiroshi,Tanaka, Masakazu
scheme or table, p. 2430 - 2439 (2012/03/27)
Chiral cyclic α,α-disubstituted amino acids, (3S,4S)- and (3R,4R)-1-amino-3,4-(dialkoxy)cyclopentanecarboxylic acids ((S,S)- and (R,R)-Ac5cdOR; R: methyl, methoxymethyl), were synthesized from dimethyl L-(+)- or D-(-)-tartrate, and their homochiral homoligomers were prepared by solution-phase methods. The preferred secondary structure of the (S,S)-Ac5cdOMe hexapeptide was a left-handed (M) 3 10 helix, whereas those of the (S,S)-Ac5cdOMe octa- and decapeptides were left-handed (M) α helices, both in solution and in the crystal state. The octa- and decapeptides can be well dissolved in pure water and are more α helical in water than in 2,2,2-trifluoroethanol solution. The left-handed (M) helices of the (S,S)-Ac5c dOMe homochiral homopeptides were exclusively controlled by the side-chain chiral centers, because the cyclic amino acid (S,S)-Ac 5cdOMe does not have an α-carbon chiral center but has side-chain γ-carbon chiral centers. Copyright
The stereoselective synthesis of novel 4-octulose derivatives
Izquierdo Cubero, Isidoro,Plaza Lopez-Espinosa, Maria T.,Rodriguezalonso, Miguel,Asenjo Asenjo, Rafael,Ramirez Fernandez, Antonio
, p. 217 - 221 (2007/10/03)
Dihydroxylation of methyl (E)-2,3-dideoxy-4,5:6,8-di-O-isopropylidene- L-xylo-oct-2-ene-4-ulofuranosonate (1) with osmium tetraoxide took place with high diastereoselectivity to give a 7:1 mixture of methyl 4,5:6,8-di-O- isopropylidene-α-L-glycero-D-galacto- (2) and -D-ido-oct-4-ulofuranosonate (3). When 1 was dihydroxylated in the presence of dihydroquinine and dihydroquinidine p-chlorobenzoate, an appreciable increase and decrease, respectively, in the 2/3 ratio was observed. Compound 2 was transformed into its 2,3-di-O-methyl derivative 4 which was deisopropylidenated to methyl 2,3- di-O-methyl-α-L-glycero-D-galacto-oct-4-ulopyranosonate (5) and subsequently degraded to dimethyl 2,3-di-O-methyl-(+)-L-tartrate (6). On the other hand, compounds 2 and 3, separately, were isopropylidenated to the corresponding 2,3:4,5:6,8-tri-O-isopropylidene derivatives 7 and 8, which were reduced with LiAlH4 to the related 2,3:4,5:6,8-tri-Oisopropylidene-α-L-glycero-D- galacto- (9) and -D-ido-oct-4-ulofuranose (10). Finally, compounds 9 and 10 were deisopropylidenated to the corresponding L-glycero-D-galacto- (11) and L-glycero-Dido-oct-4-ulose (12).
Investigations on metabolites of microoganisms, VI. Structure of the antibiotic aldgamycin E
Achenbach,Karl
, p. 759 - 771 (2007/10/05)
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