The C20 stereogenic center was secured by asymmetric hydrogenation of a β-keto ester and the configuration at both C23 and C24 was introduced by asymmetric dihydroxylation (AD).
Optically active 1-fluoroindan-1-carboxylic acid (FICA) was designed and prepared as its methyl ester for determining the absolute configuration of chiral molecules by both 1H and 19F NMR spectroscopies.
The mechanism of enzymes acting with retention or inversion of configuration during sulfate ester hydrolysis is discussed taking two complementary examples.
The helix sense of poly(propiolic esters) is determined by the configuration of the chiral center, structure of the pendant groups, temperature, and solvent.
10.7554/eLife.05808.010 Figure 3. Imaging cerebellar Purkinje cells in vivo using bulk loading of CaRuby-Nano AM. (A ) Configuration of AM-ester injection and imaging.
The latter two mixtures were converted into mixtures of (R -Mosher esteR -Mosherg (S) and (R) configuration at C-2, restersively (C-2 of thavingl correSponds to C-1 of the benzoylandd hydRoxy ketone [D1] 6).
All substrates converted with high enantioselectivities (1 a– 3 a, 7 a) were hydrolyzed with complete retention of configuration, thus yielding S-configured alcohols and unreacted R-configured sulfate esters.
Several new liquid crystalline chiral ester enantiomers in the (S) and (R) configuration were designed and characterised.
The absolute configuration of the -FICA Me ester was deduced to be (S) by X-ray crystallographic analysis of the -FICA amide of (R -α-phenethylamine.
Archaeal lipid backbones possess ether linkages and isoprenoid chains, mainly phytanyl and bysphythanediyl - archaeols and caldarchaeols- in sn-2,3 enantiomeric configuration, in contrast to the ester linkages, straight fatty acyl chains and sn-1,2 configuration of the glycerophospholipids from Eukarya and Bacteria domains [ 3].
Conversely, Si-face functionalisation with ketenes bearing either a 2-substituted aryl unit or an α-branched iso-propyl substituent provides the configuration observed for the chlorinated esters.
