Acetylene, alcohol from

Favorskii-Babayan synthesis. Synthesis of acetylenic alcohols from ketones and terminal acetylenes in the presence of anhydrous alkali. 

Methyllithium 3-Acetylene alcohols from oxido compds. 

Gung, B.W., Dickson, H.D., Seggerson, S., and Bluhm, K. (2002) A short synthesis of an acetylenic alcohol from the sponge Crihrochalina vasculum. Synth. Commun., 32, 2733—2740. 

Prior to the development of methods for caiTving out the direct reaction of fomialdehyde vdth acetydene or monosubstituted acetylenes (page 237), the only satisfactory procedime for preparing acetylenic alcohols from formaldehyde involved the intennediate preparation of organometallic compounds. Substituted pi Opargyl alcohols are obtained in yields of 70 per cent or better by reaction of monosubstituted acetylenic Grignard compounds with gaseous formaldehyde ... 

This is an example of an acetylenic alcohol. It is prepared from acetone by the following series of reactions ... 

A mixture of 0.30 mol of the acetylenic tosylate (prepared according to the general method described in VlII-3, Exp. 3 from the corresponding acetylenic alcohol, which was prepared from HC=CHgBr and CgHi3CH=0 in THF, as described in Ref. l)and 100 ml of dry acetone was added to a solution of 0.40 mol of anhydrous... 

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. 

The isophytol side chain can be synthesized from pseudoionone (Fig. 5) using chemistry similar to that used in the vitamin A synthesis (9). Hydrogenation of pseudoionone (20) yields hexahydropseudoionone (21) which can be reacted with a metal acetyUde to give the acetylenic alcohol (22). Rearrangement of the adduct of (22) with isopropenyknethyl ether yields, initially, the aHenic ketone (23) which is further transformed to the C g-ketone (24). After reduction of (24), the saturated ketone (25) is treated with a second mole of metal acetyUde. The acetylenic alcohol (26) formed is then partially hydrogenated to give isophytol (14). 

Other synthetic methods have been investigated but have not become commercial. These include, for example, the hydration of ethylene in the presence of dilute acids (weak sulfuric acid process) the conversion of acetylene to acetaldehyde, followed by hydrogenation of the aldehyde to ethyl alcohol and the Fischer-Tropsch hydrocarbon synthesis. Synthetic fuels research has resulted in a whole new look at processes to make lower molecular weight alcohols from synthesis gas. 

Unsymmetrical trans vinyl halides have been prepared from acetylenic alcohols by Corey and co-workers (as illustrated in the accompanying formulation) in connection with their synthesis of farnesol and Gecropia juvenile hormone. Several syntheses of vinyl halides (with... 

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

Acetylenic alcohols can be obtained using another technique from bromacety-lene with subsequent action of butyllithium and carbonyl compound (Scheme 63). 

Chiral lactones were also obtained by cyclocarbonylation of chiral acetylenic alcohols with Pd and thiourea (H2NCSNH2) (Scheme 32). No loss in chirality was observed, but large amounts of Pd and thiourea were used (10 mol %) since the catalyst deactivates by forming metal particles. The catalytic precursor (Pdl2 > PdCl2) and the ratio of thiourea to Pd were very important, thiourea being necessary for this reaction. The active species was supposed to be [Pd(thiourea)3l]I, which forms in situ from [Pd(thiourea)4]l2 and [Pd(thiourea)2]l2. It had to be a partially dissociated species since [Pd(thiourea)4](Bp4)2 was inactive [121]. 

Workers studying the eyelisation of acetylenic alcohols decided to make (30), Disconnection of the acetylene leaves a-hydroxy ketone (31), Since this ketone is blocked on one side by the aromatic ring it is reasonable to make (31) from (33) via bromoketone (32). Ana lysis... 

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]. 

The CCH of nitroacetylenic acetal 17 gave the corresponding amine 18 in a low yield (23%) (Scheme 6). The reduction stopped at the hydroxylamine which underwent decomposition to acetylenic alcohol 19 (11%) and an ene-yne acetal which was further reduced to diene acetal 20 (67%). The ECH in neutral medium (acetate buffer in CH3OH-H2O 93 7 v/v) has been reported to give 72% of acelylenic amine 18 (3, 10). The products resulting from the decomposition of the intermediate acetylenic hydroxylamine were not identified (3, 10). 

Highly enantioenriched 4-alken-l-yn-3-ol moieties present in many bioactive acetylenic metabolites from sponges have been efficiently obtained by reduction of the parent 1-trimethylsilyI-4-alken-l-yn-3-one 18 with Alpine-borane or with BH3-SMe2 in the presence of chiral oxazaborolidines, followed by desilylation of the resulting alcohol. This strategy has been applied to the first stereoselective synthesis of petrofuran 19 <99SL429>. 

The procedure described below is quite general and uses finely, freshly machine--powdered KOH, which is added to a solution of the primary or secondary (acetylenic) alcohol and a 10-15% molar excess of tosyl chloride in Et20, kept around 0 C The excess of tosyl chloride is destroyed during the reaction of the excess of KOH. Side- and subsequent reactions ("saponification of the ester by KOH and 1,2-elimination of p-toluenesulfonic acid from thtfester) can be suppressed by keeping the temperature of the reaction mixture below 5 C. This procedure can be carried out within 2 h and generally gives excellent (often almost quantitative) yields of the tosylates. Purification of acetylenic tosylates by distillation, which is risky because of the limited thermal stability of the esters, is not necessary because the... 

Rearrangements arc common in reactions of sulfur tetrafluoride with acetylenic and allylic alcohols. Highly acidic acetylenic alcohols derived from hexafluoroacetone and other haloacetones react readily at ambient temperature to give fluorinated allenes 10 as the sole... 

A shift from allenes to acetylenic products formed from acetylenic alcohols in which trifluoro-methyl groups are replaced by difluoromethyl groups can be explained in terms of lowering the positive character of the terminal acetylenic carbon atom, thus retarding the nucleophilic attack of fluorine at this position.56... 

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