Acetylenic alcohols synthesis

H. Laas, A. Nissen, and A. Niirrenbach, A simple synthesis of 3 i7-indoles starting from acetylenic alcohols, Synthesis, 1981, 958-959. 

Pale, P. and Chnche, J. 2000. Silver-catalyzed cyclization of acetylenic alcohols Synthesis of functionalized 2-methylene-oxolanes. Eur. J. Org. Chem. 2000 1019-1025. 

A small amount of acetylene is used in condensations with carbonyl compounds other than formaldehyde. The principal uses for the resulting acetylenic alcohols are as intermediates in the synthesis of vitamins (qv). 

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). 

Fig. 5. Synthesis ofisophytol (14) pseudoionone [141-10-6] (20), hexahydropseudoionone [1604-34-8] (21), C -acetylenic alcohol [1604-35-9] (22), C g-aUenic ketone [16647-10-2] (23), C g-diene ketone [1604-32-6] (24), C g-saturated ketone [16825-16-4] (25), and C2Q-acetylenic alcohol [29171-23-1] (26).

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... 

The acetylenic alcohol A, which was used as a key intermediate in the synthesis of ( )-7-bisabolene, served as the starting point of this synthesis. 

Synthesis of acetylenic alcohols (Section 14.8) Sodium acetylide and acetylenic Grignard reagents react with aldehydes and ketones to give alcohols of the type... 

C ( propyl) N phenylmtrone to N phenylmaleimide, 46, 96 semicarbazide hydrochloride to ami noacetone hydiochlonde, 46,1 tetraphenylcyclopentadienone to diphenyl acetylene, 46, 44 Alcohols, synthesis of equatorial, 47, 19 Aldehydes, aromatic, synthesis of, 47, 1 /3-chloro a,0 unsaturated, from ke tones and dimethylformamide-phosphorus oxy chloride, 46, 20 from alky 1 halides, 47, 97 from oxidation of alcohols with dimethyl sulfoxide, dicyclohexyl carbodumide, and pyndimum tnfluoroacetate, 47, 27 Alkylation, of 2 carbomethoxycyclo pentanone with benzyl chloride 45,7... 

The a-acetylenic alcohols were used in a synthesis of optically active 4-alkyl- y-lactones (80) (90), as shown in Scheme 11. Lactones with optical purity >... 

Acetylenic alcohols, usually of propargylic type, are frequently intermediates in the synthesis, and selective reduction of the triple bond to a double bond is desirable. This can be accomplished by carefully controlled catalytic hydrogenation over deactivated palladium [56, 364, 365, 366, 368, 370], by reduction with lithium aluminum hydride [555, 384], zinc [384] and chromous sulfate [795], Such partial reductions were carried out frequently in alcohols in which the triple bonds were conjugated with one or more double bonds [56, 368, 384] and even aromatic rings [795]. 

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>. 

Chiral allenes. A key step in a recent synthesis of the optically active pheromone of the male boll weevil (3) used the orthocstcr Claisen rearrangement for transfer of the chirality of the acetylenic alcohol 1 to the allene 2. The final product (3) shows a higher optical rotation than the naturally occurring material, which may... 

Under optimal or close to optimal conditions for the synthesis of pyrroles from ketoximes and acetylene in the KOH/DMSO system, almost none of the acetylenic alcohols are formed. 

A modified procedure illustrated by the synthesis of a diynediol (Expt 5.27) from the acetylenic alcohol, 2-methylbut-3-yn-2-ol, uses methanol and pyridine as the solvent, the latter acting also as a complexing agent for the copper(i) ions. An alternative effective coupling system involves the use of copper(n) acetate in pyridine which does not require the use of air or oxygen. 

On the other hand, acetylenic alcohols can be electrochemically converted to the corresponding acetylene carboxylic acids in acidic electrolytes using Pb02 anodes. Processes for the synthesis of propynoic acid and acetylene dicarboxylic acid have been developed at BASF 303 - 30. ... 

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... 

Using this hydrogenation as the final step simplifies the problem to a synthesis of this acetylenic alcohol. We know how to form carbon-carbon bonds next to triple bonds, and we have seen the formation of acetylenic alcohols (Section 9-7B). 

This procedure required but one resolution of the acetylenic alcohol 40 which then served to resolve the remaining chiral portion of the molecule. The resolution of octyn-3-ol 40 therefore was the start of the synthesis of the optically active 7-oxaprostanoids. Reaction of the racemic octyn-3-ol 40 with phthalic anhydride gave the phthalyl acid 41 which formed the crystalline salt 42 by reaction with ( )-o -phenethylamine with the absolute configuration shown. 

P-Acetylenic alcohols (11, 378). The propargyltitanium reagent derived from 1-trimethylsilyl-3-(tetrahydropyranyloxy)propyne (1) reacts with crotonaldehydes to afford the P-acetylenic alcohol 2 with high stereoselectivity. This alcohol was used in a stcr-eocontrolled synthesis of the natural antibiotic ( )-asperlin (6). 

Kruglikova, R. I., Sotnichenko, T. V., Shin-gareeva, A. G., and Unkovskii, B. V., Synthesis of a-acetylenic alcohol N-phenyl-carbamatcs and their intramolecular cycliza-tion into 4-alkylidcne-2oxazolidinoncs, Zh. Org. Khim.. 17,649, 1981 Chem. Abxtr.. 95, 61710, 1981. 

Metal- and alloy-containing membranes are currently applied mainly in ultrapure hydrogen production. Pilot plants with palladium alloy tubular membrane catalyst were used in Moscow for hydrogenation of acetylenic alcohols into ethylenic ones. In the Topchiev Institute of Petrochemical Synthesis, a laboratory-scale reactor of the same type was tested... 

---