Chloroformic acid esters cyclic

Cyclic carbonic from chloroformic acid esters... 

The alkanephosphonic acid dichlorides obtained by these methods are converted with amines, with all reactions carried out in solvents such as acetone, benzene, or diethyl ether at 10°C with triethylamine as HC1 captor. The conversion runs quantitatively followed by a purification with the help of column chromatography with chloroform/methanol in a ratio of 9 1 as mobile phase. The alkanephosphonic acid bisdiethanolamides could be obtained as pure substances with alkane residues of C8, C10, C12, and Ci4. The N-(2-hydroxyethane) alkanephosphonic acid 0,0-diethanolamide esters were also prepared in high purity. The obtained surfactants are generally stable up to 100°C. Only the alkanephosphonic acid bismonomethylamides are decomposed beneath this temperature forming cyclic compounds. 

In 1921 Helferich [34J found that treatment of methyl a-D-glucopyranoside 18 with sulfuryl chloride in a mixture of pyridine and chloroform at 5°C afforded a compound, the structure of which was established several years later [37,38] to be that of methyl 4,6-dichloro-4,6-dideoxy-a-D-galactopyranoside 2,3-cyclic sulfate (19 Scheme 3). The cyclic sulfates are readily cleaved by dilute alkalis, or by methanolic ammonia, to give the salt of a monosulfate the hemi-ester is then desulfated by acid to yield the chlorodeoxy sugar [35,36]. Both of these reactions occur with retention of configuration [37]. 

The addition of hydrazoic acid to numerous acyclic and cyclic alkenes also proceeds well in the presence of titanium tetrachloride or aluminum trichloride.262 Dichloromethane or chloroform are ideal solvents for these catalysts. The addition is regiospecific and tolerates the presence of primary and secondary alcohols, as well as esters (equation 184). 

The reaction 4.25 g of (+/-)-3p-acetoxy-2a-(2-methoxycarbonylethyl)-5-oxo-ip-cyclopentaneheptanoic acid methyl ester, 5-cyclic ethylene acetal in 25 ml of methanol with 6 ml of 1.00 N sodium methoxide under nitrogen at room temperature for 2 hours produced pure (+/-)-2a-(2-methoxycarbonylethyl)-3p-hydroxy-5-oxo-ip-cyclopentaneheptanoic acid methyl ester, 5-cyclic ethylene acetal after chromatographical purification with silica gel (eluent 25% acetone in chloroform). 

The above product was dissolved in 7.5 ml of methanol and 60 mg of ethylenediamine in 5 ml of methanol was added dropwise at 0°C and the mixture stirred for 45 min at 20°C. And the solvent evaporated in vacuo. The residue was chromatographed on 35 g silica gel eluting with 30% acetone and chloroform taking 40 fractions of 4 ml each. Fraction 5-14 was evaporated to dryness in vacuo affording 250 mg (+/-)-3p-hydroxy-2a-(3-oxo-l-octenyl)-5-oxo-ip-cyclopentaneheptanoic acid methyl ester, 5-cyclic ethylene acetal, Xmax (methanol, 232 nm, E 12500). 

Decarboxylation with concomitant dehydrogenation occurred in some cyclic amino acids. For example, (I)-proline was converted into a mixture of 1-pyrroline and its trimer. The methyl ester of (L)-proline was simply dehydrogenated to its /i-imine (69%). With two equivalents of IOB in chloroform (L)-proline was converted directly into 2-pyrrolidinone (70%). This transformation was less efficient for pipecolinic acid and ( )-pyrrolidinone-5-carboxylic acid [48]. 

The general methods of preparing carbonates of carbohydrates may be subdivided into four major categories, involving, respectively (a) phosgene (b) chloroformic esters (c) diesters or cyclic esters of carbonic acid and (d) other procedures which are not of universal applicabfiity. 

Keto esters can be obtained by acylation of enamines of acyclic and cyclic ketones with ethyl chloroform ate Surprisingly no -keto ester was obtained when the reaction was carried out in the presence of triethylamine and an extra mole of enamine or a tertiary aromatic amine must therefore be used to neutralize the acid liberated. The intermediate enamino ester can be isolated and reduced by hydride donors (Scheme 92). 

If the molecule is indeed bent out of a plane the nitro substituent should produce the potentiality for molecular asymmetry. Hence the nitro derivative was treated with p-boronobenzoic acid in benzene under a water separator to yield the cyclic boronate ester carboxylic acid (8). a derivative directly suitable for optical resolution. As a carboxylic acid. (8) gave a crystalline salt with quinine which, after four recrystallizations (aD — 37.4°), liberation of the organic acid, and hydrolysis gave optically active nitroglycol (6), X = NO,. Lead tetraacetate cleavage of the dextrorotatory (6), X = N02. gave optically active (5), X = NO,. the racemization of polarimetry in a chloroform solution. 

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