Acetylenes, alcohol addition

To a solution of 0.24 mol of lithium alanate in 500 ml of diethyl ether was added 0.20 mol of the acetylenic alcohol (note 1) at a rate such that gentle refluxing of the diethyl ether was maintained. After the addition the mixture was warmed under reflux for an additional 1 h. It was then cooled to 0 C and subsequently poured on to 400 g of finely crushed ice. After the remaining ice had melted the layers were separated (note 2). The aqueous layer was extracted several times with diethyl ether. The combined ethereal solutions were dried over magnesium sulfate and subsequently concentrated in a water-pump vacuum. Distillation of the residue through... 

A mixture of 0.30 mol of the tertiairy acetylenic alcohol, 0.35 mol of acetyl chloride (freshly distilled) and 0.35 mol of /V/V-diethylaniline was gradually heated with manual swirling. At 40-50°C an exothermic reaction started and the temperature rose in a few minutes to 120°C. It was kept at that level by occasional cooling. After the exothermic reaction had subsided, the mixture was heated for an additional 10 min at 125-130°C, during which the mixture was swirled by hand so that the salt that had been deposited on the glass wall was redissolved. After cooling to below 50°C a mixture of 5 ml of 36% HCl and 200 ml of ice-water was added and the obtained solution was extracted with small portions of diethyl ether. The ethereal solutions were washed with water and subsequently dried over magnesium sulfate. The solvent was removed by evaporation in a water-pump vacuum... 

A mixture of 0.10 mol of the acetylenic alcohol, 0.12 mol of triethylamine and 200 ml of dichloromethane (note 1) was cooled to -50°C. Methanesulfinyl chloride (0.12 mol) (for its preparation from CH3SSCH3, (08300)30 and chlorine, see Ref. 73) was added in 10 min at -40 to -50°0. A white precipitate was formed immediately. After the addition the cooling bath was removed and the temperature was allowed to rise to -20°0, then the mixture was vigorously shaken or stirred with 100 ml of water. The lower layer was separated off and the aqueous layer was extracted twice with 10-ml portions of CH2CI2. The combined solutions were dried over magnesium sulfate and concentrated in a water-pump vacuum (note 2). The yields of the products, which are pure enough (usually 96%) for further conversions, are normally almost quantitative. 

Tlie addition reactions of allylic and acetylenic alcohols produce compounds resulting from rearrangements [16, 17] (equation 7). 

The Favorsky reaction should be considered a general method for producing pyrazolyl-Q -acetylenic alcohols because even the less reactive 4-ethynyl-l,3,5-trimethylpyrazole, additionally deactivated by three donor methyl groups, reacts with acetone (Scheme 61). 

The intramolecular addition of the O-H bond to alkynes catalyzed by palladium complexes has been developed by K. Utimoto et al. (Eq. 6.59) [104]. An alkynyl alcohol can be converted to a cyclic alkenyl ether in the presence of a catalytic amount of [PdCl2(PhCN)2 or [PdCl2(MeCN)2] in ether or THE at room temperature. When the reaction was carried out in MeCN-H20 under reflux in the presence of a catalytic amount of PdCl2, hydration of the acetylenic alcohol occurred and the ketoalcohol was obtained in good yield instead. 

Corrosion of steel during oil well acidizing or acid pickling treatments can be controlled effectively and economically with organic corrosion inhibitors. These additives interact with the steel surface to form an adherent barrier, the nature of which depends on the additives physicochemical properties. Work to date has established that acetylenic alcohols chemisorb and subsequently polymerize on steel surfaces (1-5"). a,/MJnsaturated aldehydes and a-alkenyl-phenones appear to behave in a similar manner (6j7"). The nature of Current address Amoco Production Company, Tulsa, OK... 

The aqueous Co(CN)52- solutions under H2 have been found to catalyze hydrogenolysis of C4-unsaturated alcohols to butenes but, more remarkably, with acetylenic alcohols besides hydrogenated products secondary nitriles are also formed by addition of HCN (stoichiometric with respect to cobalt) (195) ... 

Cutting and Parsons described the transformation of acetylenic alcohols 314 into allenyl phenyl thioethers 316 by a two-step procedure (Scheme 8.85) [174], Deprotonation of alkynes 314 with n-butyllithium is followed by addition of phenylsulfenyl chloride, forming sulfenyloxy intermediates which subsequently rearrange to allenic sulfoxides 315. Treatment of allenes 315 with methyllithium results in loss of the sulfoxide moiety to form allenyl sulfides 316 in reasonable yields. 

Reduction of a, -acetylenic ketones with chiral borane NB-Enanthrane prepared by addition of 9-borabicyclo[3.3.1]nonane to the benzyl ether of nopol yielded optically active acetylenic alcohols in 74-84% yields and 91-96% enantiomeric excess [770]. Another way to optically active acetylenic alcohols is reduction with a reagent prepared from lithium aluminum hydride and (2S, 3R)-( -I- )-4-dimethylamino-3-methy 1-1,2-dipheny 1-2-butanol. At —78° mainly R alcohols were obtained in 62-99% yield and 34-90% enantiomeric excesses [893]. 

A second approach (472) to 512 started with trans-2-buitnc epoxide (524) (Scheme 67). Opening of the epoxide ring of 524 with lithium acetylide gave an acetylenic alcohol, which was converted to the acetylenic acid (525) by carbox-ylation with gaseous carbon dioxide. Partial hydrogenation of 525 followed by lactonization afforded the a,3-unsaturated lactone (526) which was transformed to the nitrolactone (527) by a Michael addition reaction of nitromethane. The Nef reaction of 527 gave the tetrahydrofuranyl acetal (528) which was converted to... 

The bromination with alkali hypobromite in aqueous solution gives good results with (hetero)arylacetylenes, enynes (RCH=CHOCH) and diynes (RC=CC=CH) all acetylenes that are more acidic than those acetylenes in the aliphadc or cycloaliphatic series with an isolated triple bond. For the conjugated systems the hypobromite method is superior to the reaction of metallated acetylenes with bromine. Various acetylenic alcohols are also brominated smoothly, which can be explained in part by their better solubility in water. Since in the case of primary and secondary ethynyl alcohols, oxidation of the alcohol can occur, the use of an excess of hypobromite should be avoided. The best procedure is drop wise additon of a small shot measure of hypobromite ro a mixture of alcohol and water. If the bromoalkynes to be prepared are not too volatile, small amounts of THF or dioxane may be added to effect a better solubility of the alkyne in the aqueous phase. Addition of a co-solvent may also be desired when the starting compound is a solid (e.g. ethynylcyclohexanol). 

W.A -Diethylaniline (0.70 mol) and redistilled acetyl chloride (0.37 mol) arc placed in the flask. The acetylenic alcohol (0.30 mol) is added over a few min while heating the mixture at ca. 40"C. An exothermic reaction starts and the temperature rises to 120 C in a few min. Occasional cooling is necessary to keep the temperature at that level. After the exothermic reaction has subsided, the mixture is heated for an additional 15 min at 130"C (immersion of the flask in the heating bath is necessary to prevent solidification of the reaction mixture on the glass wall). After cooling to 50 C (stirring has been stopped), a mixture of 300 ml of ice... 

By the extension of the above-mentioned stereoselective asymmetric addition of alkylithiums to other organolithium reagents such as lithium salts of methyl phenyl sulfide, 2-methylthiazoline, trialkylsilylacetylene, N-nitroso-dimethylamine, and acetonitrile, chiral oxiranes (95) U1), thiiranes (96) nl), acetylenic alcohols (98) 112), and amino alcohols (97) U1) were readily obtained. 

Some of the chiral acetylenic alcohols (98) were successfully converted to y-ethyl-y-butyrolactones, insect pheromones of Trogoderma. In addition, they are important intermediates for the synthesis of products with antibacterial activity113>. 

Several acetylenic epoxides have been observed to condense with methanol and other alcohols. Addition of methanol to 1,2-epoxy-S-pontyne in the presence of boron trifluoride (Eq, 567), for example, gives... 

The propargylic alcohol group may be exploited as an allylic alcohol precursor (Eq. 6A.2) and may be generated by nucleophilic addition to an electrophile [25] or by addition of a formaldehyde equivalent to a preexisting terminal acetylene group [26], Once in place, reduction of the propargylic alcohol with lithium aluminum hydride or, preferably, with sodium bis(2-methoxyethoxy)aluminum hydride (Red-Al) [27] will produce the trans allylic alcohol. Alternately, catalytic reduction over Lindlar catalyst can be used to obtain the cis allylic alcohol [28]. The addition of other lithium acetylides to ketones produces chiral secondary alcohols, which also can be reduced by the preceding methods to the cis or trans allylic alcohols. Additional synthetic approaches to allylic alcohols may be found in the various references cited in this chapter. 

Unsaturated ethers. The efficient insertion of carboalkoxycarbenes into the O—H bond of alcohols catalyzed by Rh(II) acetate (5, 571-572) extends to reactions with unsaturated alcohols. For this reaction copper(II) triflate is usually comparable to rhodium(II) alkanoates. Insertion predominates over cyclopropanation in the case of ethylenic alcohols. In reactions with acetylenic alcohols, cyclopropenation can predominate over insertion because of steric effects, as in reactions of HC=CC(CH3)2OH where the insertion/addition ratio is 36 56. 

Resolution of tert-acetylenic alcohols. Brucine forms stable 1 1 molecular complexes with only one enantiomer of several terr-acetylenic alcohols. In some liivorublc eases, complete resolution can be achieved by only one complexation in oilier eases, repetition of complexation is necessary for complete resolution. The complexes are decomposed by dilute HC1. Complexation involves a hydrogen bond between the OH group and the N atom of brucine in addition, the linearity of the acetylene group may be involved.1... 

Although, at that time, the term supramolecular chemistry had not yet been coined, the practical potential for inclusion complexation for acetylene alcohol guests 1 and 2 was recognized back in 1968 [12], Spectroscopic studies showed that 1 and 2 formed molecular complexes with numerous hydrogen-bond donors and acceptors, i.e. ketones, aldehydes, esters, ethers, amides, amines nitriles, sulfoxides and sulfides. Additionally, 1 formed 1 1 complexes with several n-donors, such as derivatives of cyclohexene, phenylacetylene, benzene, toluene, etc. The complexation process investigated by IR spectrometry revealed the presence of OH absorption bands at lower frequencies than those for uncomplexed 1 and 2 [12], These data, followed by X-ray studies, confirmed that the formation of intermolecular hydrogen bonds is the driving force for the creation of complexes [13],... 

Vinyl halides are so inert that none has been converted to a fluoride by halogen exchange. Vinyl fluorides have been synthesized from saturated polyhalides by dehalogenation with zinc and by dehydrohalo- genation with alcoholic alkali, and from acetylene by addition of one molecule of hydrogen fluoride.12 18... 

Addition of the acetylenic alcohols HC=C(CH2) OH (x = 3,4) to 1 affords a one-pot synthesis of the cyclic carbene complexes (88). The reaction proceeds via initial formation of the vinylidene complexes, followed by an intramolecular attack of the terminal alcohol function on the a carbon [Eq. (84)] (85). Combining the nucleophilicity at the /3 carbon of... 

The red R group may seem to get in the way of the reaction but, of course, the dienophile is not approaching in the plane of the diene but from underneath. Itis difficult to find a convincing example of this stereochemistry as there are so few known, partly because of the difficulty of making E,2-dienes. One good approach uses two reactions you met in Chapter 31 for the control of double bond geometry. The cis double bond is put in first by the addition of methanol to butadiyne and the trans double bond then comes from LIAIH4 reduction of the intermediate acetylenic alcohol. 

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