Acetylene derivatives ethynyl

Ethynylation. Base-catalyzed addition of acetylene to carbonyl compounds to form -yn-ols and -yn-glycols (see Acetylene-DERIVED chemicals) is a general and versatile reaction for the production of many commercially useful products. Finely divided KOH can be used in organic solvents or Hquid ammonia. The latter system is widely used for the production of pharmaceuticals and perfumes. The primary commercial appHcation of ethynylation is in the production of 2-butyne-l,4-diol from acetylene and formaldehyde using supported copper acetyHde as catalyst in an aqueous Hquid-fiHed system. 

Stabilized lithium acetyhde is not pyrophoric or shock-sensitive as are the transition-metal acetyhdes. Among its uses are ethynylation of halogenated hydrocarbons to give long-chain acetylenes (132) and ethynylation of ketosteroids and other ketones in the pharmaceutical field to yield the respective ethynyl alcohols (133) (see Acetylene-derived chemicals). 

Diol Components. Ethylene glycol (ethane 1,2-diol) is made from ethylene by direct air oxidation to ethylene oxide and ring opening with water to give 1,2-diol (40) (see Glycols). Butane-1,4-diol is stiU made by the Reppe process acetylene reacts with formaldehyde in the presence of catalyst to give 2-butyne-l,4-diol which is hydrogenated to butanediol (see Acetylene-DERIVED chemicals). The ethynylation step depends on a special cuprous... 

Ethynyl compounds react with sugar lactones to give acetylenic lactols (16,63). Reaction of 2,3-O-isopropylidene-D-ribonolactone (16a) with lithium acetylenic derivatives gave l-(2-substituted ethynyl)-2,3-0-isopropyli-dene-D-ribofuranoses. Similarly, treatment of 2,3 5,6-di-O-isopropylidene-L-gulono-1,4-lactone (9b) with various lithium acetylenic reagents gave... 

Owing to their stability and low nucleophilicity, metal acetylides are less reactive toward Cjq than other lithium organyls or Grignard reagents [11]. Though the reaction is slower and higher reaction temperatures are necessary, various acetylene derivatives of Cjq could be obtained. The first acetylene Cjq hybrids were (trimethyl-silyl)ethynyl- and phenylethynyl-dihydro[60]fullerene, synthesized simultaneously... 

Ethynylation. Condensation of acetylene with a reagent such as aldehyde to yield an acetylenic derivative. The best example is the union of formaldehyde and acetylene to produce butyne-diol, H0-CH2.C C.CH2.0H Ref CondChemDict (1961), 478-R 8th edit (1971), 375-R... 

The acetylene function exerts an electron-attracting effect. This effect can be reinforced by substitution of the acetylenic hydrogen. Ethynyl compounds are essentially found among the light sedative-hypnotic drugs (CNS-depressing effect of the unsaturated derivatives) and in steroid series, where their fixing in position 17a provides orally active steroids (Fig. 19.29). 

Guest removal and exchange were investigated for benzene-1,3,5,-TEB-silvertriflate [TEB=tm(4-ethynyl-benzonitrile)] [8] (Fig. 3c). The nitrile functionality of the trigonal phenyl-acetylene-derived ligand coordinates to silver cations forming a (3,3)-connected 3D network. A honeycomb-like structure with a channel... 

A mixture of 2-iodopyridine, phenylacetylene, activated Cu-powder, and anhydrous K2CO3 in dimethylformamide stirred 5 hrs. at 140 under Ng -(phenyl-ethynyl)pyridine. Y 88%. F. e., also with protection of alcohol groups as a-ethoxyethyl ethers (cf. Synth. Meth. 20, 22), s. M. S. Shvartsberg et al., Izvest. 1970, 1144 Eng. Transl. 1079 pyrazole derivs. s. Izvest. 1971, 1764 C. A. 75, 151724 in pyridine, prepn. of ethynylbenzenes s. ibid. 1971, 1306 C. A. 75, 88219 aliphatic acetylene derivs. with /i-butyllithium in the presence of hexamethyl-phosphoramide s. M. Schwarz and R. M. Waters, Synthesis 1972, 567. 

The interaction of (10) with vinylmagnesiiim chloride yields, after hydrolysis of the ketal group, 46% of the 3a-vinyl-l7-ketone (11b) and 7% of the 3j5-vinyl-17-ketone (12b). Ethynylation of (10) with potassium acetylide in dimethylformamide or with acetylene and potassium t-amyloxide in t-amyl alcohol-ether gives only the 3a-ethynyl derivative (11c) in 63% and 74% yields, respectively. ... 

Stavely prepared the 17a-ethynyl derivative (55) in 80% yield by reacting acetylene and (54) in the presence of potassium / -amyloxide in ether at room temperature. Sondheimer subsequently showed that a by-product obtained in 3 % yield is di-(3) ,17) -dihydroxyandrost-5-en-17a-yl)-acetylene (57). 

Terminal acetylenes can be obtained from the corresponding propylcarboxylic acids by thermal decomposition. Thus, l-methyl-3-ethynyl- and 2-methyl-3-ethynylindazole were obtained by thermolysis of indazolylpropiolic acids at 150-160°C. Yields of ethynyl derivatives were 65 and 60%, respectively (75KGS1678) (Scheme 100 Table XXIII). 

Alkylallenes are obtained by the reaction of 1-ethynylcycloalkanol acetates with organocopper reagents, lithium dimethyl- and dibutylcuprates643 (see Section B.l). Even in the case of the presence of a substituent at the acetylenic terminus, SN2 displacement takes place, giving tetra-substituted allenes. Reaction of the steroidal 17-acetoxy-17-ethynyl derivative la shows that the... 

Ethyl vinyl ether, 1 254, 258 derivation from ethanol, 10 557 physical properties of, l 255t Ethynylation, acetylene, 1 181, 231-249 Etretinate, 25 790 Etridiazole, 23 629... 

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