Amino alcohol derivatives

During attempted acetonide formation of an amino alcohol derivative, smooth tosyl cleavage was observed. The reaction is general for those cases having a carboxyl group, as in the following example, but fails for simple amino alcohol derivatives that lack this functionality. ... 

Chiral boron(III) complexes can catalyze the cycloaddition reaction of glyoxy-lates with Danishefsky s diene (Scheme 4.18) [27]. Two classes of chiral boron catalyst were tested, the / -amino alcohol-derived complex 18 and bis-sulfonamide complexes. The former catalyst gave the best results for the reaction of methyl glyoxylate 4b with diene 2a the cycloaddition product 6b was isolated in 69% yield and 94% ee, while the chiral bis-sulfonamide boron complex resulted in only... 

Enantioselectivities ranging from 18 to 94% ee were obtained by Martens et al. by using C2-symmetric bis-p-amino alcohols derived from D-cysteine for the enantioselective addition of ZnEt2 to benzaldehyde (Scheme 3.27). ... 

In addition, these authors have reported the synthesis of other A -sulfony-lated amino alcohols derived from camphor that have been examined as ligands... 

P-Nitro alcohols can be hydrogenated to the corresponding amino alcohols with retention of configuration the stereoselective Henry reaction is a useful tool in the elaboration of pharmacologically important P-amino alcohol derivatives including chloramphenicol, ephedrine, norephedrine, and others. Some important P-amino alcohols are listed in Scheme 3.11.107... 

Scheme 3.11 Biological active p-amino alcohol derivatives...

The condensation of enantiomerically pure amino alcohols (derived from amino acids) with aldehydes to furnish 1,3-oxazolidines was studied by Kuhnert and Danks in 2001 (Scheme 6.212) [382], Under solvent-free conditions, microwave irradiation of equimolar mixtures of the amino alcohol and the aldehyde for less than 3 min provided high isolated yields of 1,3-oxazolidines with excellent diastereoselectivity. In the case of (-)-ephedrine, prolonged microwave irradiation (3 min) produced quantitative conversions and high diastereoselectivities. For shorter irradiation times (80 s) mixtures of the two diastereomers were obtained with moderate conversions. 

Hydrogenation of a series of /Z-isomeric mixtures of a-arylenamides with a MOM-protected /3-hydroxyl group catalyzed by a BICP-Rh complex or an Me-DuPhos complex leads to the formation of chiral /3-amino alcohol derivatives with excellent enantioselectivities.70b A 1,4-diphosphane 26 with a rigid 1,4-dioxane backbone is also very effective for this transformation (Equation (28)).76 DIOP -Rh72a and Me-DuPhos-Rh219 catalysts are also effective for this transformation. 

In contrast to the allyltitaniums derived from acrolein cyclic acetals, such as 1,2-dicyclo-hexylethylene acetal shown in Scheme 9.8, those derived from acrolein acyclic acetals react with ketones and imines exclusively at the y-position. As shown in Eq. 9.29, the reaction with chiral imines having an optically active 1-phenylethylamine moiety proceeds with high diastereoselectivity, thus providing a new method for preparing optically active 1-vinyl-2-amino alcohol derivatives with syn stereochemistry [53], The intermediate allyltita-nium species has also found use as a starting material for a carbozincation reaction [54],... 

Sinou and coworkers evaluated a range of enantiopure amino alcohols derived from tartaric acid for the ATH reduction of prochiral ketones. Various (2R,iR)-i-amino- and (alkylamino)-l,4-bis(benzyloxy)butan-2-ol were obtained from readily available (-I-)-diethyl tartrate. These enantiopure amino alcohols have been used with Ru(p-cymene)Cl2 or Ir(l) precursors as ligands in the hydrogen transfer reduction of various aryl alkyl ketones ee-values of up to 80% have been obtained using the ruthenium complex [93]. Using (2R,3R)-3-amino-l,4-bis(benzyloxy)butan-2-ol and (2R,3R)-3-(benzylamino)-l,4-bis(benzyloxy)butan-2-ol with [lr(cod)Cl]2 as precursor, the ATH of acetophenone resulted in a maximum yield of 72%, 30% ee, 3h, 25 °C in PrOH/KOH with the former, and 88% yield, 28% ee, 120 h with the latter. 

Fuji and Kawabata further demonstrated the utility of their catalyst by successfully achieving the KR of iV-protected cyclic cw-amino alcohols [113], Hence, by using 5 mol% of 4-PPY 29 in the presence of a stoichiometric amount of collidine in CHCI3 at room temperature, a variety of cyclic cw-amino alcohol derivatives were resolved with moderate to good selectivities = 10-21) (Table 6) [113],... 

Table 6 Fuji and Kawabata s chiral 4-PPY catalyzed KR of cyclic ch-amino alcohol derivatives [113] ...

Scheme 18 Miller s tripeptide catalyzed KR of a cyclic c -amino alcohol derivative [160]...

Miller s biomimetic approach inspired Ishihara [234] to develop a minimal artificial acylase for the KR of mono-protected cw-l,2-diols and A-acylated 1,2-amino alcohols. Derived from (S)-histidine, Ishihara s organocatalyst contains only one stereogenic centre and incorporates a sulfonamide linkage in place of a polypeptide chain to allow the NH group to engage as an H-bond donor with the substrates (Fig. 13) [234]. 

The hydrogenation of a series of T/Z-isomeric mixtures of a-arylenamides containing a MOM-protected /9-hydroxyl group, using BICP-Rh and Me-DuPhos-Rh catalysts, affords the /9-amino alcohol derivatives with excellent enantioselectivity [41c]. A 1,4-di-phosphane, T-Phos, with a rigid 1,4-dioxane backbone is also a very effective Hgand for this transformation (Eq. 11) [45]. 

Figure 6.48 Proposed transition state for the proton-transfer step promoted by amino-alcohol-derived hydrogen-bonding thiourea 145.

An elegant cyclization-cleavage strategy has been devised for the removal of resin-bound 1,3-amino alcohol derivatives 392 as l,3-oxazin-2-ones 393 upon treatment with lithium hexamethyldisilazide (LiHMDS) (Equation 42) <20010L3177>. 

TABLE 7.45. AMINO ACID, AMINO ESTER AND AMINO ALCOHOL DERIVATIVES FROM HYDROGENATION OF UNSATURATED 5(4//)-OXAZOLONES... 

Table 12 shows the chemical shift for the CH-CH part of selected (/ ,/ )-tartaric acid monoesters of amino alcohols, mainly well-known /1-blockers. As can be easily seen, the chemical shifts of the (R)- and (S)-amino alcohol derivatives lie within a narrow range, dependent on the kind of tartaric acid used. Monoesters of a-amino (/f)-alcohols with (R,R)-0,0-diacetyl- or... 

The use of amino alcohol derivatives with a cyclohexyl backbone was reported recently [30b]. 

Meanwhile, addition to a-ketoester has been studied (equation 15). The chiral salen-Ti(OPr- )2 catalyst 3549 and an amino alcohol derived from hydroxyproline 3650 catalyze... 

A variety of chelate complexes of Al3+ with N and/or O donor atoms are known through stability constant data.7,8 Their formation illustrates several aspects of A1 coordination chemistry. Chelates and other multidentate ligand systems provide a means of regulating the reactivity of aluminum compounds. For example, A1 alkoxides can be converted to amino alcohol derivatives to confer water solubility and a degree of hydrolytic stability on otherwise water-sensitive materials. 

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