Synthetic Study on Pactamycin: Stereoselective Synthesis of the Cyclopentane Core Framework.

The cyclopentane core framework 23 of pactamycin (1) was synthesized in 14 steps from symmetric cyclohexadiene 11. Our synthetic strategy features Rh-mediated catalytic desymmetrization of 10 via aziridination and then regioselective ring-opening reaction of sulfonylaziridine 9 with NaN, ring-contraction of cyclohexene 14 by ozonolysis followed by intramolecular aldol reaction, and stereoselective construction of the sequential tetrasubstituted carbons by dihydroxylation and methylation reaction. Stereospecific incorporation of amine on tetrasubstituted carbon was achieved by Curtius rearrangement and subsequent carbamide formation.

Electrically induced protein release from Schizosaccharomyces pombe cells in a hyperosmotic condition during and following a high electropulsation.

A high-electric-field application of fission yeast cells under hyperosmotic conditions improved the electro-induced release of protein and cytoplasmic enzymes. A cell suspension was pulsed at 12.5 kV/cm for 10 ms in a batch system and immediately postincubated at 30 degrees C.