Sharpless asymmetric amino hydroxylation

Osmium-mediated c/s-addition of nitrogen and oxygen to olefins. Regio-selectivity may be controlled by ligand. Nitrogen sources (X-NClNa) include  

Name Reactions A Collection of Detailed Mechanisms and Synthetic Applications, DOI 10.1007/978-3-319-03979 248, Springer International Publishing Switzerland 2014 

Sharpless (USA, 1941-) shared the Nobel Prize in Chemistry in 2001 with Herbert William S. Knowles (USA, 1917-) and Ryoji Noyori (Japan, 1938-) for his work on 

Hildebrand, J. P. Muniz, K. In Catalytic Asymmetric Synthesis 2 edn., Ojima, I., Ed. Wiley-VCH New York, 2000, 399. (Review). 

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). 

Name Reactions, 4th ed., DOI 10.1007/978-3-642-01053-8 232, Springer-Verlag Berlin Heidelberg 2009 

BnOCONHa NaOH, f-BuOCI COjEt (DHQD)2AQN 

BnOCONH2 NaOH, EBuOCI C02E1 (DHQD)2AQN 

Hildebrand, J. P. Muniz, K. In Catalytic Asymmetric Synthesis 2 ed., 

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G.4 Amino-Hydroxylation. A related reaction to asymmetric dihydroxylation is the asymmetric amino-hydroxylation of olefins, forming vic-aminoalcohols. The v/c-hydroxyamino group is found in many biologically important molecules, such as the P-amino acid 3.10 (the side-chain of taxol). In the mid-1970s, Sharpless reported that the trihydrate of N-chloro-p-toluenesulfonamide sodium salt (chloramine-T) reacts with olefins in the presence of a catalytic amount of osmium tetroxide to produce vicinal hydroxyl p-toluenesulfonamides (Eq. 3.16). Aminohydroxylation was also promoted by palladium. ... 

The Sharpless asymmetric hydroxylation can take one of two forms, the initially developed asymmetric dihydroxylation (AD)1 or the more recent variation, asymmetric aminohydroxylation (AA).2 In the case of AD, the product is a 1,2-diol, whereas in the AA reaction, a 1,2-amino alcohol is the desired product. These reactions involve the asymmetric transformation of an alkene to a vicinally functionalized alcohol mediated by osmium tetraoxide in the presence of chiral ligands (e.g., (DHQD)2-PHAL or (DHQ)2-PHAL). A mixture of these reagents (ligand, osmium, base, and oxidant) is commercially available and is sold under the name of AD-mix p or AD-mix a (vide infra). 

Asymmetric dihydroxylation of trifluoromethylalkenes is also useful for construction of enantio-enriched trifluoromethylated diols usable for trifluoromethylated amino acids with chiral hydroxyl group. Thus, Sharpless AD reaction of 16 provides diol 17 with excellent enantioselectivity. Regioselective and stereospecific replacement of the sulfonate moiety in 18 with azide ion enables the introduction of nitrogen functionality. A series of well-known chemical transformation of 19 leads to 4,4,4-trifluorothreonine 20 (see Scheme 9.6) [16]. Dehydroxylative-hydrogenation of 21 by radical reaction via thiocarbonate and subsequent chemical transformation synthesize enantio-enriched (S)-2-amino-4,4,4-trifluoro-butanoic acid 22 [16]. Both enantiomers of 20 and 22 were prepared in a similar manner from (2R,3S)-diol of 17. 

Recently, Sharpless and co-workers have reported an enantioselective procedure for the vicinal addition of a hydroxyl group and amino-substituted heterocycles to olefins. They have found that simple aminopyrimidines and amino-triazines function as excellent reagents for the asymmetric aminohydroxylation. Stilbene is converted into either enantiomer of the corresponding amino alcohol with high ee s with 2-aminotriazines as the nitrogen source <1999AGE1080>. 

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