The Stereoselective Total Synthesis of the Elusive Cephalosporolide F.

Here we report a seven-step protecting-group-free stereoselective total synthesis of the elusive (+)-cephalosporolide F from d-glucose. A microwave-assisted reaction between the Meldrum's acid and the d-glucose to the respective octono-1,4-lactone derivative, and a low temperature visible-light photoredox spirocyclization of a chiral N-alkoxyphthalimide to ceph F, are the two key chemical reactions that allowed the accomplishment of this unprecedented feat under an environmentally friendly processes.

Boron Schiff bases derived from α-amino acids as nucleoli/cytoplasm cell-staining fluorescent probes in vitro.

The size, shape, and number of nucleoli in a cell's nucleus might help to distinguish a malignant from a benign tumor. Cellular biology and histopathology often require better visualization to understand nucleoli-related processes, thus organelle-specific fluorescent markers are needed. Here, we report the design, synthesis, and fully chemo-photophysical characterization of fluorescent boron Schiff bases (BOSCHIBAs), derived from α-amino acids (i.e., phenylalanine, tyrosine and tryptophan), with nucleoli- and cytoplasm-specific staining in cells. It is the first time that Boron Schiff bases derived from α-amino acids act as notorious dual (nucleoli and cytoplasm) cell-staining fluorescent probes. The boron derivatives not only showed good photostability and acceptable quantum yields (∼5%) in solution, but also exhibited low cytotoxicity (>90% cell viability at 0.1 and 1 µg mL-1), which make them good candidates to be used in medical diagnosis.

Synthesis of the Enantiomers of Tedanalactam and the First Total Synthesis and Configurational Assignment of (+)-Piplaroxide.

Highlighting the recently established methodology for the direct synthesis of glycidic amides from tertiary allyl amines, the synthesis of the enantiomers of tedanalactam were completed in two steps from the corresponding chiral dihydropiperidine. Additionally, the (+)- and (-)-enantiomers of piplaroxide were obtained from their respective tedanalactam precursor, and the absolute configuration of the naturally occurring (+)-piplaroxide was determined. The present approach represents not only the shortest synthesis of (-)-tedanalactam but also the first total synthesis of (+)-piplaroxide, a repellent against the leafcutter ant Atta cephalotes.