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1- Acyl-2-hydroxy

Yu, H., and Langer, R., Pseudopoly(amino acids) A study of the synthesis and characterization of poly(acyl-hydroxy-proline esters). Macromolecules. 22, 3250-3255, 1989. [Pg.227]

Kinetic resolutions by means of the selective formation or hydrolysis of an ester group in enzyme-catalyzed reactions proved to be a successful strategy in the enantioseparation of 1,3-oxazine derivatives. Hydrolysis of the racemic laurate ester 275 in the presence of lipase QL resulted in formation of the enantiomerically pure alcohol derivative 276 besides the (23, 3R)-enantiomer of the unreacted ester 275 (Equation 25) <1996TA1241 >. The porcine pancreatic lipase-catalyzed acylation of 3-(tu-hydroxyalkyl)-4-substituted-3,4-dihydro-2/7-l,3-oxazines with vinyl acetate in tetrahydrofuran (THF) took place in an enantioselective fashion, despite the considerable distance of the acylated hydroxy group and the asymmetric center of the molecule <2001PAC167, 2003IJB1958>. [Pg.410]

Central intermediates in our strategy were the known ortho-acylated hydroxy)... [Pg.198]

N-Trifluoroacetyl derivatives were applied in the GC analysis of amino acids in combination with different alkyl esters. TFA anhydride serves as a strong acylating agent, which is very efficient in the derivatization of all protonic groups except carboxyl. An acylation medium, usually a mixture of TFA anhydride and methylene chloride, may be injected into the GC column without any preliminary evaporation. This is a very important fact as TFA derivatives are very sensitive towards moisture and mere evaporation can lead to decomposition, particularly of acylated hydroxy and thiol groups. Possible losses of more volatile derivatives are also eliminated. [Pg.129]

A similar ring closure is observed when the carbodiimide with an acylated hydroxy group in the /3-position 640 is treated with ammonia to give the heterocycle 641. ... [Pg.112]

Following another synthetic pathway, an intramolecular cycloaddition was carried out by treating the JV-acylhydroxylamine 5 a with tetrapropylammonium periodate in chloroform. Under these conditions intramolecular [4 + 2] cycloaddition occurs with complete simple diastereoselectivity to give the corresponding bicyclic dihydro-1,2-oxazine cis-6a as the sole product118-121. However, when the IV-acyl hydroxy larnine bears a substitutent R1 the stereocontrol is incomplete. [Pg.1087]

In a variant (15) of the carbodiimide method, two moles of an A-alkoxycarbonylamino acid are reacted with one mole of DCC in dichloromethane (DCM). After 30 minutes, the DCU is removed by filtration and the solution is mixed with the aminolyzing component. The DCM is sometimes replaced with dimethylformamide (DMF) for the aminolysis step. SyAn formation is very slow in DMF. The method is wasteful of substrate but gives clean reactions. Some SyAn have been isolated and stored (16, 17), but the practice is no longer in vogue. SyAn are less reactive and hence more selective than OAIU they do not acylate hydroxy groups that have not been deprotonated. They are especially effective for acylating secondary amines such as A-methylamino-acid residues. [Pg.293]

Similarly, y-bromobutyrolactone, an intramolecularly acylated hydroxy carboxylic acid, is converted by saturation with dry HBr into 4-bromobutyric acid, which yields its methyl ester in 85-90% yield when boiled for several hours with methanol (3 moles), CH2C12 (300 ml), and concentrated H2S04... [Pg.236]

Rock, C. O., Fitzgerald, V., Rainey, W. T. Jr., Snyder, F. 1976. Mass spectral identification of 2-(o-acyl)hydroxy fatty acid esters in the white portion of the rabbit Harderian gland. Chem. Phys. Lipids, 17, 207—212. [Pg.357]

In peptide syntheses, where partial racemization of the chiral a-carbon centers is a serious problem, the application of 1-hydroxy-1 H-benzotriazole ( HBT") and DCC has been very successful in increasing yields and decreasing racemization (W. Kdnig, 1970 G.C. Windridge, 1971 H.R. Bosshard, 1973), l-(Acyloxy)-lif-benzotriazoles or l-acyl-17f-benzo-triazole 3-oxides are formed as reactive intermediates. If carboxylic or phosphoric esters are to be formed from the acids and alcohols using DCC, 4-(pyrrolidin-l -yl)pyridine ( PPY A. Hassner, 1978 K.M. Patel, 1979) and HBT are efficient catalysts even with tert-alkyl, choles-teryl, aryl, and other unreactive alcohols as well as with highly bulky or labile acids. [Pg.145]

When unsubstituted, C-5 reacts with electrophilic reagents. Thus phosphorus pentachloride chlorinates the ring (36, 235). A hydroxy group in the 2-position activates the ring towards this reaction. 4-Methylthiazole does not react with bromine in chloroform (201, 236), whereas under the same conditions the 2-hydroxy analog reacts (55. 237-239. 557). Activation of C-5 works also for sulfonation (201. 236), nitration (201. 236. 237), Friede 1-Crafts reactions (201, 236, 237, 240-242), and acylation (243). However, iodination fails (201. 236). and the Gatterman or Reimer-Tieman reactions yield only small amounts of 4-methyl-5-carboxy-A-4-thiazoline-2-one. Recent kinetic investigations show that 2-thiazolones are nitrated via a free base mechanism. A 2-oxo substituent increases the rate of nitration at the 5-position by a factor of 9 log... [Pg.402]

Acyl derivatives, RCO—NH—OH and HjN—O—CO—R, are named as A-hydroxy derivatives of amides and as O-acylhydroxylamines, respectively. The former may also be named as hydroxamic acids. Examples are A-hydroxyacetamide for CH3CO—NH—OH and O-acetylhydrox-ylamine for HjN—O—CO—CH3. Further substituents are denoted by prefixes with O- and/or A-locants. For example, C5H5NH—O—C2H5 would be O-ethyl-A-phenylhydroxylamine or A-ethox-ylaniline. [Pg.32]

Cocatalysts of two types occur (/) proton-donor substances, such as hydroxy compounds and proton acids, and (2) cation-forming substances (other than proton), including alkyl and acyl haUdes which form carbocations and other donor substances leading to oxonium, sulfonium, halonium, etc, complexes. [Pg.564]

Mocimycin has been chemically converted to aurodox by protection of the 4-hydroxy group at the pyridone moiety as the benzoylformate, followed by /V-methylation and hydrolytic removal of the protective group (1,55). Whereas aurodox esters are active growth promotors in animals, goldinamines that are A/-acylated by acids other than goldinonic acid, such as acetic, benzoic, or arylsulfonic acids, lack useful antimicrobial or growth-promoting activity (1). [Pg.524]

The primary transporter of cholesterol in the blood is low density Hpoprotein (LDL). Once transported intraceUularly, cholesterol homeostasis is controlled primarily by suppressing cholesterol synthesis through inhibition of P-hydroxy-P-methyl gluterate-coenzyme A (HMG—CoA) reductase, acyl CoA—acyl transferase (ACAT), and down-regulation of LDL receptors. An important dmg in the regulation of cholesterol metaboHsm is lovastatin, also known as mevinolin, MK-803, and Mevacor, which is an HMG—CoA reductase inhibitor (Table 5). [Pg.130]

Chiral Lactones and Polyesters. Similar to intermolecular reactions described previously. Upases also catalyze intramolecular acylations of hydroxy acids the reactionsults in the formation of lactones. [Pg.341]

Regioselective Acylation of Hydroxy Compounds. AUphatic diols can be selectively acylated at the primary position by a number of Upases in nonaqueous solvents. For example, PPL suspended in solutions of various diols in ethyl carboxylates catalyzes transesterification in a highly regioselective manner, producing primary monoesters in up to 97% yield (93). Similarly, chloramphenicol [56-75-7] (72) (R = NO2) can be acylated by a number of Upases to produce optically pure, water-insoluble 3-0-palmitate in a highly selective manner (94). [Pg.341]

A number of steroids have been regioselectively acylated ia a similar manner (99,104). Chromobactenum viscosum hpase esterifies 5a-androstane-3P,17P-diol [571-20-0] (75) with 2,2,2-triduoroethyl butyrate ia acetone with high selectivity. The hpase acylates exclusively the hydroxy group ia the 3-position giving the 3P-(monobutyryl ester) of (75) ia 83% yield. In contrast, bacillus subtilis protease (subtihsia) displays a marked preference for the C-17 hydroxyl. Candida iylindracea]i 2Lse (CCL) suspended ia anhydrous benzene regioselectively acylates the 3a-hydroxyl group of several bile acid derivatives (104). [Pg.342]

When large groups, such as phenyl, bromo, ethoxycarbonyl or nitro are attached at position 3, the principal products are l-alkylcinnolin-4(l/f)-ones. Cyanoethylation and acetylation of cinnolin-4(l/f)-one takes place exclusively at N-1. Phthalazin-l(2/f)-ones give 2-substituted derivatives on alkylation and acylation. Alkylation of 4-hydroxyphthala2in-l(2/f)-one with an equimolar amount of primary halide in the presence of a base leads to 2-alkyl-4-hydroxyphthalazin-l(2/f)-one and further alkylation results in the formation of 4-alkoxy-2-alkylphthalazinone. Methylation of 4-hydroxy-2-methyl-phthalazinone with dimethyl sulfate in aqueous alkali gives a mixture of 4-methoxy-2-methylphthalazin-l(2/f)-one and 2,3-dimethylphthalazine-l,4(2//,3//)-dione, whereas methylation of 4-methoxyphthalazin-l(2/f)-one under similar conditions affords only 4-methoxy-2-methylphthalazinone. [Pg.17]


See other pages where 1- Acyl-2-hydroxy is mentioned: [Pg.133]    [Pg.42]    [Pg.84]    [Pg.825]    [Pg.235]    [Pg.608]    [Pg.713]    [Pg.825]    [Pg.43]    [Pg.73]    [Pg.2330]    [Pg.597]    [Pg.272]    [Pg.243]    [Pg.143]    [Pg.1076]    [Pg.105]    [Pg.517]    [Pg.484]    [Pg.157]    [Pg.435]    [Pg.86]    [Pg.28]    [Pg.98]    [Pg.282]    [Pg.341]    [Pg.343]    [Pg.343]    [Pg.57]   
See also in sourсe #XX -- [ Pg.133 ]




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2-Pyrones 3-acyl-4-hydroxy-, reactions

3-hydroxy acylation

3-hydroxy acylation

Acyl bromides hydroxy

Acyl-l,5-dihydro-4-hydroxy-2-pyrrolones

Acylation (s. a. Acoxy hydroxy compounds

Acylation hydroxy groups with acidic functions

Acylation, hydroxy groups

Hydroxy acid, protected, acyl

Hydroxy adds acylation

Hydroxy adds acylation with

Hydroxy compounds, acylation

Hydroxy compounds, acylation coupling

Hydroxy compounds, acylation reactions

Hydroxy hindered, acylation

Hydroxy protection specific acyl groups

Hydroxy thiols, acylation

Hydroxy-acyl CoA dehydrogenase

Ketones, y-hydroxy via acylation of boron-stabilized carbanions

Long-chain 3-hydroxy acyl-CoA dehydrogenase

Long-chain 3-hydroxy acyl-CoA dehydrogenase deficiency

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