First synthesis and characterization for the stereoisomers of Ulipristal acetate
The three stereoisomers, 11α,17α-isomer I, 11α,17β-isomer II and 11β,17β-isomer III are related substances of the selective progesterone receptor modulator Ulipristal acetate. Herein, we presented an efficient and practical synthesis approach to deliver these three stereoisomers for the first time, and also confirmed the structure of the key intermediate 5a by single-crystal X-ray analysis. Our research will be of immense help for organic chemists to study the impurity profile of Ulipristal acetate.
Design and synthesis of a novel class of sugar-peptide hybrids: C-linked glyco beta-amino acids through a stereoselective "acetate" Mannich reaction as the key strategic element.
A new type of sugar-amino acid hybrid, which is comprised of a sugar unit (gluco-, galacto-, or mannopyranose) linked through a C-glycosidic linkage to the beta-position of an alpha-unsubstituted beta-amino acid unit, is presented. It is hypothesized that these new compounds, or the oligomeric peptides derived therefrom, might possess the structural features of beta-amino acid oligomers and the chemical and enzymatic resistance of C-glycosides to hydrolysis. The synthetic strategy is based on a new Mannich-type reaction between a chiral acetate enolate equivalent and alpha-amido sulfones derived from the corresponding sugar-C-glycoside aldehydes. While the sugar-C-glycoside aldehyde partner is prepared from well-established transformations on known sugar precursors, the lithium enolate derived from (1R)-endo-2-acetylisoborneol 3 is employed as the key element. This Mannich approach proceeds with essentially perfect diasteromeric control leading to the new beta-amino carbonyl adducts in good yields. Further, cleavage of the camphor auxiliary is smoothly performed by oxidative treatment with ammonium cerium nitrate (CAN). Complementarily, direct peptide-type coupling of the beta-amino carbonyl Mannich adducts with an alpha- or beta-amino acid residue and subsequent CAN-promoted detachment of the auxiliary yields dipeptide fragments bearing a sugar-containing aliphatic side chain and is a process that can be iterated. A preliminary conformational study based on the combination of experimental NMR data and molecular mechanics and molecular dynamics (MD) of one particular adduct is also provided.
Teaching learning disability to undergraduate medical students
The education of doctors shapes their professional identity: who they are and how they practise. Where does the issue of learning disability fit in? What is it and of what factors should doctors in training be aware?

The training of medical students has been defined by the General Medical Council (