Aminohydroxylation, reviews

Asymmetric epoxidation, dihydroxylation, aminohydroxylation, and aziridination reactions have been reviewed.62 The use of the Sharpless asymmetric epoxidation method for the desymmetrization of mesa compounds has been reviewed.63 The conformational flexibility of nine-membered ring allylic alcohols results in transepoxide stereochemistry from syn epoxidation using VO(acac)2-hydroperoxide systems in which the hydroxyl group still controls the facial stereoselectivity.64 The stereoselectivity of side-chain epoxidation of a series of 22-hydroxy-A23-sterols with C(19) side-chains incorporating allylic alcohols has been investigated, using m-CPBA or /-BuOOH in the presence of VO(acac)2 or Mo(CO)6-65 The erythro-threo distributions of the products were determined and the effect of substituents on the three positions of the double bond (gem to the OH or cis or trans at the remote carbon) partially rationalized by molecular modelling. 

Osmium-catalysed dihydroxylation has been reviewed with emphasis on the use of new reoxidants and recycling of the catalysts.44 Various aspects of asymmetric dihydroxylation of alkenes by osmium complexes, including the mechanism, acceleration by chiral ligands 45 and development of novel asymmetric dihydroxylation processes,46 has been reviewed. Two reviews on the recent developments in osmium-catalysed asymmetric aminohydroxylation of alkenes have appeared. Factors responsible for chemo-, enantio- and regio-selectivities have been discussed.47,48 Osmium tetraoxide oxidizes unactivated alkanes in aqueous base. Isobutane is oxidized to r-butyl alcohol, cyclohexane to a mixture of adipate and succinate, toluene to benzoate, and both ethane and propane to acetate in low yields. The data are consistent with a concerted 3 + 2 mechanism, analogous to that proposed for alkane oxidation by Ru04, and for alkene oxidations by 0s04.49... 

In 1975 Sharpless and coworkers discovered the stoichiometric aminohydrox-ylation of alkenes by alkylimido osmium compounds leading to protected vicinal aminoalcohols [1,2]. Shortly after, an improved procedure was reported employing catalytic amounts of osmium tetroxide and a nitrogen source (N-chlo-ro-N-metallosulfonamides or carbamates) to generate the active imido osmium species in situ [3-8]. Stoichiometric enantioselective aminohydroxylations were first reported in 1994 [9]. Finally, in 1996 the first report on a catalytic asymmetric aminohydroxylation (AA) was published [10]. During recent years, several reviews have covered the AA reaction [11-16]. 

The second supplement to the three volume reference work Comprehensive Asymmetric Catalysis critically reviews new developments to the hottest topics in the field written by recognised experts. Seven chapters which are already treated in the major reference work have been supplemented, and additionally a new chapter on Aminohydroxylation of Carbon-Carbon Double Bonds has been included. Thus the state-of-the art in this area is now re-established. Together with the basic three volume book set and Supplement 1 it is not only the principal reference source for synthetic organic chemists, but also for all scientific researchers who use chiral compounds in their work (for example, in biochemical investigations and molecular medicine) as well as for pharmaceutical chemists and other industrial researchers who prepare chiral compounds. 

Contrary to the osmium-catalyzed dihydroxylation (DH) [80], the aminohydroxylation (AH) [18, 81] adds two different heteroatoms (N, O) to double bonds. It provides straightforward access to the amino alcohol fragment present in a broad variety of namral products (Fig. 8). Numerous reviews [20, 22, 82-87] have been published, among others, by its inventor K. B. Sharpless [17, 20, 88], who also rendered it asymmetric and catalytic at the same time in 1996 [89,90],... 

Nilov, D. Reiser, O. Recent Advances on the Sharpless Asymmetric Aminohydroxylation. In Organic Synthesis Highlights Schmalz, H.-G. Wirth, T., eds. Wiley-VCH Weinheim, Germany 2003,118-124. (Review). 

HP as the oxygen source, have been reviewed, with major focus on the their synthetic potential. Recent experimental investigations of the nature of catalytically active species and mechanisms of their action are summarized.Asymmetric oxidation reactions, viz., sulfoxidation, epoxidation, dihydroxylation, and aminohydroxylation in water have been reviewed. The focus is on the development of catalytic oxidation in water, particularly the use of HP in the presence of metal catalysts. The enantioselective oxidation of sulfides to sulfoxides is also included. ... 

---