Amines allylic, dihydroxylation

Additionally, 1,2-dihydroxyethylene dipeptide analogues without the C-terminal carboxylic acid have been used to obtain aspartyl proteases inhibitors.[641 These efforts include stereoselective alkylation of imines, one-pot reductive amination of epoxy ketones, ring opening of epoxides with sodium azide, diastereoselective dihydroxylation of allylic amines, and enzymatic resolution and stereocontrolled intramolecular amidation. 

The allylic amination with benzylamine or related amines such as (3,4-dimethoxy-phenyl)methylamine catalyzed by palladium coordinated with the dihydroxylated ferrocenylphosphine 8b takes place with high enantioselectivity (Scheme 2-30) [27]. Thus, reaction of l,3-diphenyl-2-propenyl ethyl carbonate 41 with benzylamine gives a quantitative yield of allylic amination product 42 with > 97% ee. High enantioselectivity is also obtained in the allylic amination of 2-propenyl esters 43 substituted... 

The product (112) of D-xylose, allyl amine, and styrylboronic acid was then subjected to a protection/metathesis/dihydroxylation/deprotection/cyclization sequence that produced stereoisomerically pure (-F)-uniflorine A over a total of 11 steps. 

Kinetic resolution of racemic allylic acetates has been accomplished via asymmetric dihydroxylation (p. 1051), and 2-oxoimidazolidine-4-carboxy-lates have been developed as new chiral auxiliaries for the kinetic resolution of amines. Reactions catalyzed by enzymes can be utilized for this kind of resolution. ... 

The same 3-si lyl-( )-hex-4-enoates have been transformed into /-lactones 67 and 68 by asymmetric dihydroxylation (Scheme 13).[62 821 After mesylation the remaining hydroxyl was substituted by an azide with inversion of configuration. When the silane group was first eliminated to give the allyl azide 69, reduction of the latter could not be achieved. Therefore, reduction and Boc protection of the resulting amine was performed before silane elimination, to give the Boc-protected dipeptide isostere 70. 

Consequently, a dihydroxylated azidodialdehyde was examined next which indeed behaved as anticipated. When generated from the racemic allylic azide 37 [109], FruA catalysis effected a smooth tandem addition to the dialdehyde to provide a diastereoisomerically pure bipyranoid azido C-disaccharide 38, from which the pyrrolidine type aza sugar 39 was highly stereoselectively produced by standard reductive amination [108]. Model considerations suggest a close resemblance of the protonated aza C-disaccharide to transition states of saccha-rase or maltase. Indeed, several of the glycosidases tested were inhibited by 39 at concentrations below 1 mM. 

Corey, E. J., Guzman-Perez, A., Noe, M. C. The application of a mechanistic model leads to the extension of the Sharpless asymmetric dihydroxylation to allylic 4-methoxybenzoates and conformationally related amine and homoallylic alcohol derivatives. J. Am. Chem. Soc. 

The chelating nature of the diamine precludes osmate ester hy-droysis in situ and means that the oxidation of an alkene requires 1 equiv of osmium tetroxide, followed by a step to release the glycol. However, the use of catalytic amounts of transition metal in the directed dihydroxylation of allylic amides was shown to be possible (eq 31) by using a monodentate amine (quinuclidine, which is released in situ from quinuclidine-A(-oxide). These conditions are catalytic in osmium but generally exhibit a less powerful directing effect than stoichiometric osmium tetroxide and TMEDA. 

Yet another approach by Corey and Snider [43] utilised a novel allylic functionalisation of the acetal (37) with 7V-phenyltriazolinedione to give the intermediate (38), the A -methyl derivative of which afforded the hydrazine (39a) on dihydroxylation of the olefinic bond and hydrolysis of the lirazole moiety with potassium hydroxide. Hydrogenolysis then led to the amine (39b) which underwent ring contraction to (lOd) on treatment with sodium nitrite in aqueous acetic acid. 

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