Amino alcohols azido ketones

The reagent reduces all types of azides, yields in monofunctional azides being 80-90% . Azido ketones yield amino alcohols while unsaturated azides retain the double bonds, thus reduction of 3-azido-4-hydroxy-l-butene (4) gave 3-amino-4-hydroxy-l-butene (5) . ... 

An efficient DKR of p-azido alcohols was reported in 2001 by Backvall and coworkers. The chiral p-azido alcohol products are useful as direct precursors of aziridines and p-amino alcohols. Shvo s catalyst 1 (4—6 mol%) was used for the racemization and CALB for the kinetic resolution [74]. Good isolated yields (70-87%) of the products were obtained with enantiomeric excesses exceeding 99% in many cases (13). In all cases, small amounts of the corresponding ketones (2-8%) were observed as by-products during the hydrogen transfer process, probably due to the high temperature used (80°C). 

Aube and co-workers have found that enolizable ketones react with benzyl azide in triflic acid to yield /V-(phenylamino)-methylated products [Eq. (5.354)]. The transformation is an aza-Mannich reaction interpreted with the involvement of the Mannich reagent A -phenyl iminium ion 295 formed in situ in a Schmidt rearrangement. Cyclic tertiary alcohols react with alkyl azides in triflic acid to yield N-alkylamines (296, 297)983 [Eq. (5.355)]. The Schmidt rearrangement was used to transform Merrifield resin into amino-polystyrene resin by reacting the azido derivative in excess triflic acid (CH2CI2, 0°C).984... 

This reaction was first reported by Corey and T.ink in 1992. It is an enantioselective synthesis of a -amino acids by means of the asymmetric reduction of trichloromethyl ketones from catechoiborane in the presence of either (/ )- or (5)-oxazaborolidine, followed by the treatment of the resulting alcohols with base and sodium azide and subsequently the reductive conversion of the azido group into an amino group. Therefore, this reaction is generally known as the Corey-Link reaction. Occasionally, it is also referred to as the Corey-Link amino acid synthesis, Corey-Link procedure, etc. 

Scheme 12.60. The trichloromethyl ketone is reduced with catecholborane in the presence of the (5 )-oxazaborohdine catalyst. The resulting (i )-secondary alcohol (produced in high enantioselectivity) is treated with sodium hydroxide and sodium azide to yield the corresponding (5 )-a-azido carboxylic acid, and reduction then produces the amino acid (after Corey, E. J. Link, J. O. /. Am.Chem.Soc., 1992,114,1906).

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