Hydroxy compounds, with Alcohols

Supplement (combined with Volumes XVIII and XIX) XVII, 2nd 1934 2359-3031 Hydroxy compounds Furfuryl alcohol, 112. Carbonyl compounds Butyrolactone, 234. Furfural, 272. 2-Aoetyl-thio-phene, 287. Xanfhone, 366. Succinic anhydride, 404. Phthalio anhydride, 469. 

In the condensation of diols, halogenated alcohols, amino alcohols, cyclic hydroxy ethers, or other bifunctional hydroxy compounds with carbodiimides, 5-, 6-, and 7-membered 1,3-O-N- or l,3-7V,7V-heterocyclics are obtained [14]. 

Both aromatic and aliphatic fluoroformates 7 can be readily prepared from phenols or alcohols and carbonyl difluoride and treated with sulfur tetrafluoride without isolation. Hydrogen fluoride evolved in the reaction of hydroxy compounds with carbonyl di fluoride serves as a catalyst for the consecutive reaction with sulfur tetrafluoride.15<)-162 This provides a general, convenient, direct synthesis of aryl and alkyl trifluoromethyl ethers 5 from phenols and alcohols. When the intermediate fluoroformate 7 is isolated prior to treatment with sulfur tetrafluoride, at least one mole equivalent of hydrogen fluoride is necessary to promote the fluorination reaction. 159 163 Representative examples of the conversion of hydroxy compounds 6 into trifluoromethyl ethers 5 via intermediate fluoroformates 7 are given (for other examples 7 -> 5, see Houben-Weyl, Vol. E4, pp 628. 629). 

OH, hydroxy compounds or alcohols with ol in their names, e.g. CH3 CH2 CH2OH, propan-l-ol or 1-hydroxypropane ... 

Hydride reductions of (7) can be controlled to give either the (R) or (5) secondary hydroxy compound with good selectivity by choice of the reducing agent. Lithium Tri-s-butylborohydride (L-Selectride ) provided the (5)-alcohol (according to Cram s chelate rule) and Diisobutylaluminum Hydride (DIBAL) gave the (R)-carbinol in excess (eq 7). The DIBAL results were rationalized in terms of the open-chain Comforth dipole model. ... 

A very selective method of oxidizing secondary alcohols is bromino-lysis of tributyltin ethers prepared by the treatment of hydroxy compounds with bis(tributyl)tin oxide. The reaction is regio- and stereospecific and is an important means of oxidizing unprotected glycosides [734]. 

The reaction of hydroxy compounds with numerous nucleophiles in the presence of diethyl azodicarboxylate/triphenylphosphine has been investigated . Epimerization with simultaneous O-acylation in the presence of the above reagents, a method initially used in steroid chemistry has been successfully applied to prostaglandin derivatives Recently, this method has been used for the preparation of prim. (lR)[l- Hi]- and -alcohols of high optical purity . 

Further work on the preparation of cryt/iro-2-alkyl-3-hydroxy-esters (140) by various condensations between propionic acid derivatives and aldehydes has been reported " the use of zirconium enolates seems to be particularly efficacious. Rules for predicting the stereochemical outcome of condensations between lithium enolates of esters and ketones and a-alkoxy-aldehydes have also been delineated. Pure erythro-isomer (140) can also be obtained in some cases by reduction of the corresponding jS-keto-ester with zinc borohydride. In related work it has been found that sodium borohydride in isopropanol reduces t-butyl a-alkoxy-j8-keto-esters to the corresponding -hydroxy compounds with erythro-threo ratios of between 2 1 and 20 1 in favour of the eryt/iro-isomer. In an extension of his previous work, Frdter has reported that dianions derived from cyclohexanol (141) can be alkylated with 95% stereoselectivity, to give (142). When the starting alcohol (141) is optically pure, a sequence of alkylation and oxidation leads to 2-ethoxycarbonylcyclohexanones with 76% enantiomeric enrichments. 

Other Reactions. Treatment of an active hydroxy compound with 2,2 -dipyridyl disulfide and n-BuyP yields the corresponding thiopyridyl derivative. This methodology has been applied to the preparation of 5-arylthio-5 -deoxyribonucleosides (eq 8). Monophosphate esters [R0P(0)(0H)2] will react similarly to form the activated triphenylphosphonium adduct, which, in the absence of an added external nucleophile, dimerizes yielding a pyrophosphate. A-Methylimidazole has been found to catalyze this transformation. The addition of alcohols or amines, however, traps the phosphoryloxyphosphonium salt as the mixed diphosphate ester or mixed ester/amide, respectively (eq 9). Chlorotrimethylsilane and (pyS)2 have also been reported to facilitate the oxidation of phosphites to phosphates. ... 

Six protective groups for alcohols, which may be removed successively and selectively, have been listed by E.J. Corey (1972B). A hypothetical hexahydroxy compound with hydroxy groups 1 to 6 protected as (1) acetate, (2) 2,2,2-trichloroethyl carbonate, (3) benzyl ether, (4) dimethyl-t-butylsilyl ether, (5) 2-tetrahydropyranyl ether, and (6) methyl ether may be unmasked in that order by the reagents (1) KjCO, or NH, in CHjOH, (2) Zn in CHjOH or AcOH, (3) over Pd, (4) F", (5) wet acetic acid, and (6) BBrj. The groups may also be exposed to the same reagents in the order A 5, 2, 1, 3, 6. The (4-methoxyphenyl)methyl group (=MPM = p-methoxybenzyl, PMB) can be oxidized to a benzaldehyde derivative and thereby be removed at room temperature under neutral conditions (Y- Oikawa, 1982 R. Johansson, 1984 T. Fukuyama, 1985). 

Reactions with Alcohols, Phenols, and Other Hydroxy Compounds... 

The reaction with sodium sulfite or bisulfite (5,11) to yield sodium-P-sulfopropionamide [19298-89-6] (C3H7N04S-Na) is very useful since it can be used as a scavenger for acrylamide monomer. The reaction proceeds very rapidly even at room temperature, and the product has low toxicity. Reactions with phosphines and phosphine oxides have been studied (12), and the products are potentially useful because of thek fire retardant properties. Reactions with sulfide and dithiocarbamates proceed readily but have no appHcations (5). However, the reaction with mercaptide ions has been used for analytical purposes (13)). Water reacts with the amide group (5) to form hydrolysis products, and other hydroxy compounds, such as alcohols and phenols, react readily to form ether compounds. Primary aUphatic alcohols are the most reactive and the reactions are compHcated by partial hydrolysis of the amide groups by any water present. 

The reaction of alcohols and acid chlorides in the presence of magnesium has been described (68). With primary and secondary alcohols the reaction is very smooth, and affords high and sometimes quantitative yields. Difficulty esteritiable hydroxy compounds such as tertiary alcohols and phenols can be esteritied by this method. The reaction carried out in ether or benzene is usually very vigorous with evolution of hydrogen. 

The most common impurities are the corresponding acid and hydroxy compound (i.e. alcohol or phenol), and water. A liquid ester from a carboxylic acid is washed with 2N sodium carbonate or sodium hydroxide to remove acid material, then shaken with calcium chloride to remove ethyl or methyl alcohols (if it is a methyl or ethyl ester). It is dried with potassium carbonate or magnesium sulfate, and distilled. Fractional distillation then removes residual traces of hydroxy compounds. This method does not apply to esters of inorganic acids (e.g. dimethyl sulfate) which are more readily hydrolysed in aqueous solution when heat is generated in the neutralisation of the excess acid. In such cases, several fractional distillations, preferably under vacuum, are usually sufficient. 

The purification of diethyl ether (see Chapter 4) is typical of liquid ethers. The most common contaminants are the alcohols or hydroxy compounds from which the ethers are prepared, their oxidation products (e.g. aldehydes), peroxides and water. Peroxides, aldehydes and alcohols can be removed by shaking with alkaline potassium permanganate solution for several hours, followed by washing with water, concentrated sulfuric acid [CARE], then water. After drying with calcium chloride, the ether is distilled. It is then dried with sodium or with lithium aluminium hydride, redistilled and given a final fractional distillation. The drying process should be repeated if necessary. 

In some cases products of rearrangement are obtained either partially or exclusively on treatment of Grignard reagents with epoxides. Thus, reaction of the 2/ ,3/ -epoxide (14) with methyl Grignard reagent affords a mixture of two epimeric secondary A-nor alcohols (15) in 80% yield and the tertiary hydroxy compound, 2a-methyl-5a-cholestan-2/f-ol (16) in 15 % yield. ... 

The stereochemistry of the product resulting from the reaction of a 17-keto steroid with ethylidenetriphenylphosphorane is different from that of the 17-ethylidene steroids obtained by dehydration of 17a-ethyl-17/ -hydroxy compounds, Wolff-Kishner reduction of A -20-keto steroids or by sodium-alcohol or sodium-ammonia " reductions of 17-ethynyl carbinols. These latter products have generally been assumed to possess the trans configuration (C-21 methyl away from the bulk of the ring system) because of anticipated greater stability. The cis configuration for... 

In contrast to phosphorus esters, sulfur esters are usually cleaved at the carbon-oxygen bond with carbon-fluorine bond formation Cleavage of esteri nf methanesulfonic acid, p-toluenesidfonic acid, and especially trifluoromethane-sulfonic acid (tnflic acid) by fluoride ion is the most widely used method for the conversion of hydroxy compounds to fluoro derivatives Potassium fluoride, triethylamine trihydrofluoride, and tetrabutylammonium fluoride are common sources of the fluoride ion For the cleavage of a variety of alkyl mesylates and tosylates with potassium fluoride, polyethylene glycol 400 is a solvent of choice, the yields are limited by solvolysis of the leaving group by the solvent, but this phenomenon is controlled by bulky substituents, either in the sulfonic acid part or in the alcohol part of the ester [42] (equation 29)... 

One of the most useful ways of introducing fluorine into organic compounds is the placement of the hydroxyl group in alcohols hydroxy compounds, and carboxylic acids Methyl alcohol reacts with anhydrous hydrogen fluoride at 100 500 °C in the presence of aluminum fluoride [60, 61], zinc fluoride [62] chromium fluonde [63], or a mixture of aluminum and chromium fluondes [64] to give a 20-78% yield of fluoromethane Attempted fluorinations of higher alcohols by this method failed [60]... 

X0 to hydroxy compounds. Lower temperatures favor ketone formation and sterically hindered carbonyls, such as 2-thienyl t-butyl ketone, are not reduced. The sensitivity of desulfurization to steric factors is evident by the failure to desulfurize 2,5-di-i-butyl-3-acetylthiophene. The carbonyl groups of both aldehydes and ketones can be protected by acetal formation, as particularly cyclic acetals are stable during desulfurization in methanol at room temperature. " The free aldehydes give primary alcohols on desulfurization. Another method to obtain only keto compounds is to oxidize the mixtures of ketone and secondary alcohol with CrOs after the desulfurization. - Through the desulfurization of 5,5 -diacetyl-2,2, 5, 2"-terthienyl (228), 2,15-hexadecandione (229) has been obtained, which... 

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