Asymmetric Dihydroxylation of Alkenes

Abstract

The oxidation of alkenes to vicinal diols using osmium tetroxide is one of the most selective and reliable transformations in organic synthesis. The reaction stereospecifically produces a cis‐1,2‐glycol and is tolerant of a wide array of functional groups. Methods have been developed to oxidize alkenes stoichiometrically, as well as in the presence of catalytic amounts of osmium tetroxide, when a suitable secondary oxidant is present. The latter process is particularly useful considering the expense and toxicity of osmium tetroxide. The utility of dihydroxylation in organic synthesis is enhanced by the facile transformations of the cis‐1,2‐diol products into other useful derivatives. Among the most versatile intermediates are the corresponding cyclic sulfates, which serve as reactive epoxide equivalents that can be used singly or doubly displaced with amine‐, oxygen‐, sulfur‐, or carbon‐based nucleophiles. The reaction of osmium tetroxide with alkenes is accelerated by several orders of magnitude in the presence of coordinating amine ligands such as triethylamine, quinuclidine, or diazobicyclooctane. The logical extension to asymmetric osmylation of alkenes in the presence of chiral amine bases spurred the study of asymmetric dihydroxylation. The breakthrough of catalytic turnover in the cinchona alkaloid‐osmium tetroxide system revolutionized the field of asymmetric dihydroxylation. Specialized ligands have been developed to provide position selectivity in the dihydroxylation of polyenes, efficient kinetic resolution of racemic substrates, and high levels of enantioselectivity for each of six alkene classes.

Synthesis of Perdeuterated 1‐Palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine ([D82]POPC) and Characterisation of Its Lipid Bilayer Membrane Structure by Neutron Reflectometry

“…Next, we applied the Sharpless method of asymmetric dihydroxylation to O‐benzyl‐protected deuterated allyl alcohol . Deuterated allyl alcohol was synthesised from propiolic acid (Scheme ), which was reduced with 25 % molar excess of lithium aluminium deuteride at room temperature by following the procedure reported by Benedict and Russell (which utilises LiAlH 4 ) .…”

Aggrecanase: The Family and Its Inhibitors

“…5)). The specified compound displayed IC 50 values of <10 nM for aggrecanase and MMP-13, and much less activity against TACE and MMP-1 [85].…”

Allyl Ether

“…[16][17][18] As double bond isomerization is a common side reaction in several ring-closing or cross-metathesis reactions, 19 protocols were developed to prevent these undesired isomerizations. For instance, exposure of diallyl ether to second-generation Grubbs' catalyst at elevated temperature for a prolonged period of time results in the quantitative formation of the isomerized product 2,3-dihydrofuran (6). Addition of 10 mol % of acetic acid or benzoquinone to the metathesis reaction results in complete suppression of the isomerization reaction and 2,5-dihydrofuran (5) .…”