Hydroxyproline Ethers

In a study of the deprotection of the MEM ethers of hydroxyproline and serine derivatives, it was found that the MEM group was stable to conditions that normally cleave the t-butyl and BOC groups [CF3COOH, CH2CI2, 1 1 (v v)]. The MEM group was also stable to 0.2 N HCl, but not stable to 2.0 N HCl or HBr-AcOH. ... 

Early examples of enantioselective extractions are the resolution of a-aminoalco-hol salts, such as norephedrine, with lipophilic anions (hexafluorophosphate ion) [184-186] by partition between aqueous and lipophilic phases containing esters of tartaric acid [184-188]. Alkyl derivatives of proline and hydroxyproline with cupric ions showed chiral discrimination abilities for the resolution of neutral amino acid enantiomers in n-butanol/water systems [121, 178, 189-192]. On the other hand, chiral crown ethers are classical selectors utilized for enantioseparations, due to their interesting recognition abilities [171, 178]. However, the large number of steps often required for their synthesis [182] and, consequently, their cost as well as their limited loadability makes them not very suitable for preparative purposes. Examples of ligand-exchange [193] or anion-exchange selectors [183] able to discriminate amino acid derivatives have also been described. 

HydTOX5 proline-derived polyesters are usually readily soluble in a variety of organic solvents (benzene, toluene, chloroform, dichloro-methane, carbon tetrachloride, tetrahydrofuran, dimethylformamide, etc.) As expected, the solubility in hydrophobic solvents increased with increasing chain length of the N protecting group, while the solubility in polar solvents decreased. For example, poly(N-hexanoyl-hydroxyproline ester) is slightly soluble in ether but easily soluble in acetonitrile, while poly(N-palmitoylhydroxyproline ester) is readily soluble in ether but virtually insoluble in acetonitrile. 

At this stage in our work, Benn and his colleagues ( ) described a synthesis of crotanecine from (2S,4R)-4-hydroxyproline ( ) in which the silyl ether (3 ) is an intermediate. The subsequent reactions are similar to our own projected synthesis, involving both ( ) and (34). 

Surprisingly few studies have been directed towards the development of noncinchona alkaloid-based catalysts for the alcoholative ASD of meso-anhydrides, or indeed any of the enantioselective alcoholysis processes. Uozumi has reported a series of (2S, 4R)-4-hydroxyproline-derived 2-aryl-6-hydroxyhexahydro-lfi-pyr-rolo[l,2-c] imidazolones which mediate the methanolytic ASD of ds-hexa-hydrophthalic anhydride in up to 89% ee when employed at the 10 mol% level for 20 h at —25 °C in toluene [186]. Additionally, Nagao has described the use of a bifunctional chiral sulfonamide for the thiolytic ASD of meso-cyclic anhydrides in up to 98% ee when employed at the 5 mol% level for 20 h at rt in ether [187]. 

Properties Colorless crystals. Very soluble in water slightly soluble in alcohol insoluble in ether. Optically active, dZ-hydroxyprolinc, mp 261-262C with decomposition.Z-hydroxyproline, mp 270C (natural). rZ-hydroxyproline, mp 274C. 

The catalytic efficiencies of some 1,3- and 1,4-amino alcohols remain high. Except for one ligand derived from hydroxyproline, most others are based on ferrocene. A similar ligand is a Cr(CO)j complex. /3-Hydroxy ethers and /3-amino thiols are also attracting a great deal of attention. 

L-Proline [147-85-3] M 115.1, m 215-220°(dec)(D-isomer), 220-222°(dec) (L-form), 205°(dec)(DL-isomer), [a] -53° (c 0.6, 0.5N HCl), -93° (c 2.4,6N KOH) for L-isomer), pi 6.3, pKf 1.95 pKJs 10.64. A likely impurity is hydroxyproline. Purify L-proline via its picrate which is crystallised twice from water, then decomposed with 40% H2SO4. The picric acid is extracted with diethyl ether, the H2SO4 in solution is precipitated with Ba(OH)2, and the filtrate is evaporated. The residue is crystallised from hot absolute EtOH [Mellan Hoover J Am Chem Soc 12 3879 1951] or EtOH/Et20. Its solubility in H2O is >100%. It sublimes... 

Behenamidopropyl PG-dimonium chloride conditioner, shaving PPG-14 butyl ether conditioner, shaving creams Behenamidopropyl dimethylamine behenate Dipalmltoyl hydroxyproline conditioner, shaving preps. 

Behenamidopropyl PG-dimonium chloride Canolamidopropyl betaine Cocamidopropyl betaine Cocamidopropyl lauryl ether Cocoyl sarcosine Dilaureth-4 dimonium chloride Dimethicone copolyol phthalate N,N-Dimethyl-N-lauric acid-amidopropyl-N-(3-sulfopropyl)-ammonium betaine N,N-Dimethyl-N-myristyl-N-(3-sulfopropyl)-ammonium betaine N,N-Dimethyl-N-palmityl-N-(3-sulfopropyl)-ammonium betaine N,N-Dimethyl-N-stearyl-N-(3-sulfopropyl)-ammonium betaine N,N-Dimethyl-N-tallow-N-(3-sulfopropyl)-ammonium betaine Dipalmitoyl hydroxyproline Disodium cocamido MEA-sulfosuccinate Disodium cocoamphodipropionate Disodium lauroamphodiacetate... 

Hydroxyproline has been incorporated to a PEG-500 monomethyl ether polymer by means of a succinate spacer rendering catalyst 192 (30 mol%. Fig. 4.38),... 

Separate glucosylation and galactosylation of hydroxyproline using peracetates and boron trifluoride etherate as catalyst and solid-phase procedures led to compounds (53) and (54), and a further solid-phase process involved treating resin-bonded peptides with the... 

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