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.
A new and efficient method for the synthesis of rocuronium bromide
Rocuronium bromide has been used as an aminosteroid non-depolarizing neuromuscular blocker and muscle relaxant. In this work, a new and efficient route for preparing a key intermediate 2β-(4-morpholinyl)-16β-(1-pyrrolidinyl)-5α-androstan-3α,17β-diol (6) was developed through a ring-opening of epoxide followed by introducing and pyrrolidine. Compound 6 can easily provide rocuronium bromide and the overall yield of compound 6 in 5 steps increased to 57.8%, which was higher than currently reported methods. Extraordinarily, this method would avoid the generation of disubstituted impurities E and F which are difficult to remove.
The Chemistry of the Semiconductor Industry
Overview. Semiconductor silicon. Group III-V compounds. Group II-VI semiconductors. Chemical vapour deposition. Plasma-enhanced chemical vapour deposition. Metal-organic vapour phase epitaxy. Liquid-phase epitaxy of III-V compounds. Photoresists. X-ray and E-beam resists. Wet etching. Polyimides. Molecular electronics. Computer modelling. Plasma etching. Polymers in plasmas.