Amino alcohols carbonates

Urethane hydrolyzes into an amine, an alcohol, and carbon dioxide. So the possible degradation products of a poly(phosphoester-urethane) are diamines, diols, phosphates, carbon dioxide, and even ureas. Urea is possible because the isocyanate is extremely sensitive to moisture, which would convert the isocyanate to an amino group. One is therefore bound to have traces of diamine in the polymerization that leads to a urea bond in the backbone. We think the cytotoxicity seen in the macrophage functional assay comes from the TDI structure. 

To increase the yields of the ring closure reactions, a new method was developed that was successfully applied for the synthesis of alicyclic fused systems of both the parent oxazolidine-2-thione and tetrahydro-1,3-oxazine-2-thione (85S1149). As an example, the synthesis of 2-thioxoperhydro-l,3-benzoxazine 103 is described. The dithiocarbamate 101, prepared from the amino alcohol 100, carbon disulfide and triethylamine, was treated with ethyl chloroformate in the presence of triethylamine, to give the thioxo derivative 103 via the transition state 102 (85S1149). In this way, the fused-skeleton thioxooxazines (91, X = S, 92) can be prepared with considerably higher yields (50-70%) than by the earlier methods (85S1149). 

Acetal (4) undergoes 5k 1 hydrolysis in aqueous solution at high pH, it is easily monitored via the -nitrophenoxide chromophore produced.3 The reaction has been used to probe hydration effects in co-solvents alcohols, amino acids, and peptides— the last two as models for such effects in enzymes. Primary alcohols retard the reaction in proportion to their carbon number, but the amino acids and peptides show more complex effects, which are interpreted in terms of interactions between the overlapping hydration shells of the amino and carboxylate groups. 

The p-amino-a-hydroxy esters have been converted to diamino acids [88, 89] and related compounds like the nitrogen-substituted azetidinone shown in Scheme 13, a key structure in the synthesis of the commercially available antibiotic loracarbef [90] by substitution of the alcohol moiety with an azide. Several approaches have been used to achieve this transformation. Mesylation of the alcohol followed by substitution with sodium or trimethylsilyl azide provided cis-diamino acids [88,89]. trans-Diamino acids were obtained by ring opening of the aziridine [88] or by inversion of the alcohol bearing carbon followed by substitution under Mitsunobo conditions [90]. 

Metal rf-inline complexes with various transition metals [1-10] and lanthanides [11,12] are well known in the literature. Early transition metal if-imine complexes have attracted attention as a-amino carbanion equivalents. Zirconium rf-imine complexes, or zirconaaziridines (the names describe different resonance structures), are readily accessible and have been applied in organic synthesis in view of the umpolung [13] of their carbons whereas imines readily react with nucleophiles, zirconaaziridines undergo the insertion of electrophilic reagents. Accessible compounds include heterocycles and nitrogen-containing products such as allylic amines, diamines, amino alcohols, amino amides, amino am-idines, and amino acid esters. Asymmetric syntheses of allylic amines and a-amino acid esters have even been carried out. The mechanism of such transformations has implications not only for imine complexes, but also for the related aldehyde and ketone complexes [14-16]. The synthesis and properties of zirconaaziridines and their applications toward organic transformations will be discussed in this chapter. 

The C chemical shifts and some selected C- H spin coupling constants of compound 73 and its hydrochloride are collected in Table 48. The data show a high degree of consistency - in nearly all cases the chemical shifts for carbons of the amino alcohol chain (carbons C-H) are somewhat reduced when switching from the free bases to the hydrochloride salts (the opposite trend is observed for the corresponding H chemical shifts) <2001MOL796>. 

Diallyl dicarbonate was used for the allyloxycarbonyl protection of amino compounds including amino acids, amino sugars and nucleosides. Except for the reaction with amino acids, the reagent does not require an additional base, and the only by-products, allyl alcohol and carbon dioxide are both volatile. For example, N-allyloxycarbonyl glucosamine was obtained analytically pure by simple evaporation of the reaction mixture. 

Aqueous solution of a-amino amides has been found to exhibit good reversible absorption capacity of carbon dioxide compared to amino alcohols when carbon dioxide is absorbed under 1 atm. However, the absorption capacity of a-amino amides is highly dependent on the partial pressure of carbon dioxide, the absorption capacity being considerably decreasing when carbon dioxide is absorbed under 0.1 atm. 

Reagents formed by combining PhjP with CCU and with diethyl azodicarboxylate (DEAD) promote cyclization of amino alcohols to cyclic amines (Scheme 26). Various 2-amino alcohols reacted with diethoxytriphenylphosphorane (66) to afford the corresponding aziridines in 85-90% yields. The reaction proceeds with retention of the configuration at the amino carbon (C-2) (Scheme 26). In view of... 

Isobutyl chloroformate is most frequently applied in peptide chemistryfollowed by ethyl chloto-formate (see Table 1). The advantage of this method is that the mixed anhydride does not have to be isolated, and during work-up only carbonic acid half esters are formed, which decompose to an alcohol and carbon dioxide. Only in the case of sterically hindered amino acids does the opening of the anhydride at the undesired carbonyl occur in considerable amounts. Furthermore, short activation times (30 s) at low temperatures lead to peptides with minimal racemization. With isopropenyl chloroformate the mixed anhydride is prepared at room temperature, and during reaction only acetone and carbon dioxide are formed. 

C. Yet another and very elegant method has been worked out by Rosen 292). The reaction of amino alcohols with carbon disulfide is carried out in the presence of iodine. In this way N-(2-hydroxyalkyl)-thiuram disulfides (LXVIII) are formed which may be thermally decomposed into the oxazolidine-2-thiones (LXI). These reactions are... 

Sour tastes are produced by the hydrogen ions in acids and salty tastes by the anions of salts (for example, chloride ions). Bitterness is due primarily to a class of compounds called alkaloids examples are quinine, caffeine, and nicotine. Many substances other than sugar evoke a sweet taste, including ethylene glycol (antifreeze), alcohols, amino acids, and certain salts of lead and beryllium [for example, lead carbonate hydroxide (white lead), Pb3(0H)2(C03)2]. (The sweet flavors of ethylene glycol and lead paint are blamed for the unwitting consumption of these toxic substances by children and animals.)... 

Most applications of liquid column chromatography are now made on silica which has been chemically modified (bonded phase chromatography). The modification is made by chemical reaction between the silanol groups and a chlorosilane compound. The carbon radicals of the chlorosilane compound determines the nature of the final column material. Using silanes containing alkyl carbon chains with 8-22 carbon atoms gives the particles hydrophobic surfaces, but more polar surfaces may be obtained by incorporation of alcohol, amino, cyano or other groups in the alkyl chain. 

In the reaction of the anhydride 1 with amino alcohols and carbon disulfide in the presence of potassium hydroxide compounds 121 are formed with 75-79% yields [71, 72],... 

H. Matsuda, A. Baba, R. Nomura, M. Kori, S. Ogawa, Improvement of the process in the synthesis of 2-oxazoHdinones from 2-amino alcohols and carbon dioxide by use of triphenylstilbine oxide as catalyst, Ind. Eng. Chem. Prod. Res. Dev. 24 (1985) 239-242. 

Y. Kubota, M. Kodaka, T. Tomohiro, H. Okuno, Formation of cyclic urethanes from amino alcohols and carbon dioxide using phosphorus(III) reagents and halogenoalkanes, J. Chem. Soc. Perkin Trans. I (1993) 5-6. 

Benzoates. Dissolve 0-5 g. of the amino acid in 10 ml. of 10 per cent, sodium bicarbonate solution and add 1 g. of benzoyl chloride. Shake the mixture vigorously in a stoppered test-tube remove the stopper from time to time since carbon dioxide is evolved. When the odour of benzoyl chloride has disappeared, acidify with dilute hydrochloric acid to Congo red and filter. Extract the solid with a little cold ether to remove any benzoic acid which may be present. RecrystaUise the benzoyl derivative which remains from hot water or from dilute alcohol. 

Dissolve 5 g. of finely-powdered diazoaminobenzene (Section IV,81) in 12-15 g. of aniline in a small flask and add 2-5 g. of finely-powdered aniline hydrochloride (1). Warm the mixture, with frequent shaking, on a water bath at 40-45° for 1 hour. Allow the reaction mixture to stand for 30 minutes. Then add 15 ml. of glacial acetic acid diluted with an equal volume of water stir or shake the mixture in order to remove the excess of anihne in the form of its soluble acetate. Allow the mixture to stand, with frequent shaking, for 15 minutes filter the amino-azobenzene at the pump, wash with a little water, and dry upon filter paper Recrystallise the crude p-amino-azobenzene (3-5 g. m.p. 120°) from 15-20 ml. of carbon tetrachloride to obtain the pure compound, m.p. 125°. Alternatively, the compound may be recrystaUised from dilute alcohol, to which a few drops of concentrated ammonia solution have been added. 

In addition to alcohols, some other nucleophiles such as amines and carbon nucleophiles can be used to trap the acylpalladium intermediates. The o-viny-lidene-/j-lactam 30 is prepared by the carbonylation of the 4-benzylamino-2-alkynyl methyl carbonate derivative 29[16]. The reaction proceeds using TMPP, a cyclic phosphite, as a ligand. When the amino group is protected as the p-toluenesulfonamide, the reaction proceeds in the presence of potassium carbonate, and the f>-alkynyl-/J-lactam 31 is obtained by the isomerization of the allenyl (vinylidene) group to the less strained alkyne. 

Metabolic Functions. Zinc is essential for the function of many enzymes, either in the active site, ie, as a nondialyzable component, of numerous metahoenzymes or as a dialyzable activator in various other enzyme systems (91,92). WeU-characterized zinc metahoenzymes are the carboxypeptidases A and B, thermolysin, neutral protease, leucine amino peptidase, carbonic anhydrase, alkaline phosphatase, aldolase (yeast), alcohol... 

The condensation may occur one to three times, depending on the number of hydrogen atoms on the a-carbon of the nitroparaffin, giving rise to amino alcohols with one to three hydroxyl groups. A comprehensive review of these compounds has been pubUshed (1). 

The elemental and vitamin compositions of some representative yeasts are Hsted in Table 1. The principal carbon and energy sources for yeasts are carbohydrates (usually sugars), alcohols, and organic acids, as weU as a few other specific hydrocarbons. Nitrogen is usually suppHed as ammonia, urea, amino acids or oligopeptides. The main essential mineral elements are phosphoms (suppHed as phosphoric acid), and potassium, with smaller amounts of magnesium and trace amounts of copper, zinc, and iron. These requirements are characteristic of all yeasts. The vitamin requirements, however, differ among species. Eor laboratory and many industrial cultures, a commercial yeast extract contains all the required nutrients (see also Mineral nutrients). 

Cyanohydrin Synthesis. Another synthetically useful enzyme that catalyzes carbon—carbon bond formation is oxynitnlase (EC 4.1.2.10). This enzyme catalyzes the addition of cyanides to various aldehydes that may come either in the form of hydrogen cyanide or acetone cyanohydrin (152—158) (Fig. 7). The reaction constitutes a convenient route for the preparation of a-hydroxy acids and P-amino alcohols. Acetone cyanohydrin [75-86-5] can also be used as the cyanide carrier, and is considered to be superior since it does not involve hazardous gaseous HCN and also virtually eliminates the spontaneous nonenzymatic reaction. (R)-oxynitrilase accepts aromatic (97a,b), straight- (97c,e), and branched-chain aUphatic aldehydes, converting them to (R)-cyanohydrins in very good yields and high enantiomeric purity (Table 10). 

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