2011年7月1日 · Thankfully, using so much OsO4 has been made completely unnecessary by using the co-oxidant N-methylmorpholine N-oxide (NMO). OsO4 can be made to be even more reactive and even react with very electron-poor alkenes through adding pyridine, which coordinates to osmium and renders it more electron-rich.

The Upjohn Dihydroxylation allows the syn -selective preparation of 1,2-diols from alkenes by the use of osmium tetroxide as a catalyst and a stoichiometric amount of an oxidant such as NMO (N -methyl morpholine- N -Oxide). The toxic and volatile OsO 4 can also be prepared in situ by the oxidation of K 2 OsO 2 (OH) 4 with NMO.

2021年12月16日 · N-methylmorpholine N-oxide (NMO) is one of the most commonly employed co-oxidants. In such condition, osmium compounds are re-oxidized by NMO and can be reused to react with more alkenes, so only small molar percentage of OsO 4 …

2015年2月22日 · N-methyl-morpholine-N-oxide (NMO) is used to reoxidize and regenerate osmium tetroxide ($\ce{OsO4}$) in what is known as the "Upjohn Dihydroxylation" procedure. Mechanistically, the redox occurs when a lone pair of electrons on the reduced $\ce{Os(VI)O3}$ are used to form a bond to the morpholine N-oxygen; the electrons from the former $\ce{N-O ...

2019年2月13日 · Vicinal syn dihydroxylation complements the epoxide-hydrolysis sequence which constitutes an anti dihydroxylation of an alkene. When an alkene reacts with osmium tetroxide, stereocenters can form in the glycol product. Cis alkenes give meso products and trans alkenes give racemic mixtures.

To convert alkenes into cis-diols by syn dihydroxylation, they are reacted with a basic solution of potassium permanganate (KMnO4) or Osmium tetroxide (OsO4): Both reactions go through the formation of a cyclic intermediate which is formed by a syn addition to the double bond.

2020年7月26日 · This video shows an elaborate mechanism of Alkene syn dihydroxylation reaction in presence of Osmium tetroxide and N-methylmorpholine N-oxide with Hydrogen Peroxide. The hydrolysis reaction...

Sharpless asymmetric dihydroxylation (also called the Sharpless bishydroxylation) is the chemical reaction of an alkene with osmium tetroxide in the presence of a chiral quinine ligand to form a vicinal diol.

Vicinal syn dihydroxylation complements the epoxide-hydrolysis sequence which constitutes an anti dihydroxylation of an alkene. When an alkene reacts with osmium tetroxide, stereocenters can form in the glycol product. Cis alkenes give meso …

Syn -dihydroxylation of olefins occur via the reaction with osmium tetroxide. Cycloaddition of osmium tetroxide with ethene proceeds via a cyclic transition state to form an osmate ester. Addition occurs on the same side of the ethene molecule to give a syn -addition. Work-up with water gives the syn -diol and reduced Osmium (VI).