Carbonic acid monoester

Scheme 4.351665 illustrates the most common method for synthesising carbonates — reaction of the hydroxyl group with a chloroformate in the presence of base - and a particularly mild method of deprotection, hydrogenolysis, giving toluene and a carbonic acid monoester that decarboxylates to liberate the free hydroxyl.666 Alkoxycarbonyl groups can be easily installed on carbohydrates by reaction with the appropriate chloroformate in the presence of TMEDA at low... 

Cyclocarboxylation. Propargylic alcohols add to CO2 in the presence of DBU and the salts of the carbonic acid monoesters rapidly cychze when AgOAc is present to activate the triple bond. 

Intramolecular substitutions. A ring expansion at the expense of cyclopropane ring scission has been shown. A glycosyl carbonate extrudes COj on exposure to Me SiOTf, as a result of ionization, decarboxylation of the carbonic acid monoester, and the return of the alcohol residue to the anomeric site. ... 

Due to the ability of coordinating with 1,3-dicarbonyl compounds, Mg(C104)2 reacts with diethyl dicarbonate to form complex (II), which can undergo the addition of the alcohol to form intermediate (in). An internal proton shift in (m) can produce intermediate (IV), which can irreversibly decompose to the mixed carbonate (VI) and to the carbonic acid monoester (V). Owing to its high instability, (V) immediately produces EtOH and CO2. The irreversibility of the last two steps drives the overall process towards (HI). This explanation accounts for the formation of the mixed carbonate (VI) as the major product of the reaction (Jousseaume et al., 2003). 

In a series of communications between 1959 and 1962, Ugi described the four-component condensation of an oxo-containing species, amine, isocyanide, and carboxylic acid to give a-acylamino carboxamide products. This discovery introduced the multicomponent reaction to the field of peptide chemistry and, thus, dramatically increased its applicability. Ugi showed that a broad range of nucleophilic components — including hydrogen sulfide, hydrogen selenide, hydrazoic acids, cyanates, thiocyanates, carbonic acid monoesters, salts of secondary amines, and water - were viable partaers in the reaction. In addition, procedures made use of either ketones or aldehydes as the oxo-containing component. Primary or secondary amines, hydroxylamines, ammonia, hydrazides and hydrazines were found to successfully participate as the amine component. 

The classical Ugi four-component reaction (U-4CR) originally described by Ugi et al. [1] consists in the reaction of a primary amine, a carbonyl compound (aldehyde or ketone), an isocyanide, and a carboxylic acid to afford a-acylamino amides 36 (Scheme 7.14) [31, 32], Rapidly, other components or adducts were found to give the Ugi-4CR—that is, ammonia, hydroxylamine, or hydrazine as amine component or thiosulfates [33], thiocarboxylic acids [34], isothiocyanic acids [35], hydrazoic acid [36], or carbonic acid monoesters... 

One final example within this context is discussed here and this chemistry was reported by the Minakata group [86]. The synthesis starts with the use of butynyl or butenyl alcohols, which can be converted in situ to carbonic acid monoesters by treatment with CO2 (Figure 10). Although being elusive intermediates and supposed to be highly... 

In any reaction where the cleavage of a carbon-hydrogen bond is important, the introduction of a metal ion into the molecule in the proper position will facilitate reaction. For example, in the elimination of the elements of a phosphoric acid monoester from the molecule below, the electrostatic attraction of the cupric ion facilitates removal of the proton on the o -carbon atom with subsequent elimination of the phosphoryl residue (8). 

Protected-amino phosphonic acid monoesters 51 are usually activated by conversion to the phosphonochloridates 52, then coupled with appropriate amine components such as C-protected amino adds or peptides to give phosphonoamidates 53 (Scheme 17). This procedure is in contrast to typical peptide coupling conditions, in which carboxylic acid chlorides are avoided because of their susceptibility to epimerization at the a-carbon. Since enolate-... 

Suzuki et al. [Ill] screened three solvents—methylene chloride, diethyl ether, and benzene—to determine their ability to produce optimum elution of phthalic acid monoesters sorbed on a styrene divinylbenzene polymer (Figure 2.40). The effect of elution solvent strength on the recovery of the free acid form of the monomethyl (MMP), ethyl (MEP), -propyl (MPRP), K-butyl (MBP), K-pentyl (MPEP), and -octyl (MOP) phthalates is compared. The phthalic acid monoesters are arranged in Figure 2.40 in the order of increasing number of carbons in the alkyl chain, which in turn is roughly correlated with an increase in hydrophobicity. 

A plausible mechanism is shown in Figure 17.33. It is assumed that the enolate, not the ketone itself, reacts with the permanganate. The Mn( )4 anion presumably reacts with the enolate carbon electrophilically with one of its doubly bonded O atoms. The manganese(V) acid monoester C is formed and is oxidized by a permanganate ion to give the analogous man-ganese(VII) acid monoester F. The subsequent chemistry of F is difficult to predict. 

At temperatures around 200°, a-hydroxyacetates are transformed to oxiranes via a tautomeric ortho-monoester with neighboring-group participation. By the action of heat. CO2 is split off the carbonic acid esters of 1,2-diols and oxiranes are formed. Disecondary or ditertiary 1,2-diols react with diaryldialkoxysulfurane 66 by antiperiplanar intramolecular nucloephilic displacement via a (3-hydroxy-alkoxysulfonium ion intermediate 67 (Eq. 56). ... 

BromineJbarium carbonate/barium hydroxide Phosphoric from phosphorous acid monoesters... 

Monoesters of carbonic acid lose carbon dioxide easily. The loss of carbon dioxide... 

FIGURE 17.55 Monoesters of carbonic acid decarboxylate easily, but carbonates (acid diesters) do not. 

Sodium hydroxide/sodium carbonate Partial and total O-alkylation of phenols Sulfuric acid monoesters as reactants... 

Obviously then, any situation where an alkyl phosphoric add ester-hydrocarbon mixture is liquid or even partially liquid will lead to some measure of selective migration into the powder and therefore antifoam deactivation. Such situations could occur during periods of storage of the powder at elevated temperatures or when the antifoam is sprayed directly onto hot powder immediately after production from a spray-drying tower, as described by Curtis et al. [35]. The antifoam exemplified in this patent consisted of a mixture of a commercial (Cig-Cig) alkyl phosphoric acid monoester and a petroleum jelly, which is a hydrocarbon gel at ambient temperatures with a carbon number >25. Mixing petroleum jelly with the phosphoric acid monoester in the preferred ratio of 1 3 by weight produces an effective antifoam precursor with a drop melting point of 58°C. Curtis et al. [35] describe both full-plant scale... 

Potassium carbonate Phosphoric acid monoesters from dichlorophosphinic acid esters... 

Another amino-protecting group is 1,1-dimethylethoxycarbonyl (tert-butoxycarbonyl, Boc), introduced by reaction with bis(l,l-dimethylethyl) dicarbonate (di-tert-butyl dicarbonate). Similar to carbamic acids, the leaving group, (CH3)3COCOOH, is an unstable monoester of carbonic acid (see Problem 36, part (a), of Chapter 22). It decomposes spontaneously to CO2 and (CH3)3C0H. 

Fig. 2. Synthesis of uma2enil (18). The isonitrosoacetanihde is synthesized from 4-f1iioroani1ine. Cyclization using sulfuric acid is followed by oxidization using peracetic acid to the isatoic anhydride. Reaction of sarcosine in DMF and acetic acid leads to the benzodiazepine-2,5-dione. Deprotonation, phosphorylation, and subsequent reaction with diethyl malonate leads to the diester. After selective hydrolysis and decarboxylation the resulting monoester is nitrosated and catalyticaHy hydrogenated to the aminoester. Introduction of the final carbon atom is accompHshed by reaction of triethyl orthoformate to...

Succinic acid is absorbed from aqueous solutions by anion-exchange resins or active carbon (9—11). Succinic anhydride forms rhombic pyramidal or bipyramidal crystals. It is relatively insoluble in ether, but soluble in boiling chloroform and ethyl acetate. Succinic anhydride reacts with water and alcohols, giving the acid and monoesters, respectively. 

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