Ethynyl carbinols

Ethynyl carbinols rearrange to conjugated unsaturated aldehydes. Copper or silver salts cataly2e isomeri2ation of the acetate to an aHenic acetate, which can be hydroly2ed to an unsaturated aldehyde (204). 

Isomertaation of ethynyl carbinols to unsaturated catt>ony( coinpounds. 

The partial hydrogenation of a 17-ethynyl group over deactivated palladium occurs more readily than the saturation of any other functional group. This is also true of 17-ethynyl carbinols and 17-acetylenic ethers (52). ... 

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... 

Therapeutic Function Sedative, hypnotic Chemical Name 1-chloro-3-ethyl-1-penten-4-yl-3-ol Common Name Ethyl (3-chlorovinyl ethynyl carbinol Structural Formula C H... 

The prevalence of 17-ethynyl carbinols among the orally active 19-nor progestins can lead to the impression that this is a necessary group for activity. The good potency shown by a compound that possesses the 17-hydroxy 17-acetyl moiety more characteristic of the 19-methyl progestins indicates that the structure-activity relationship is not quite that narrow. One... 

Prior to our original report7 on this method, acceptable and general preparative routes to a-iodocycloalkenones had not been described. Treatment of a p-substituted cycloalkenone with trimethylsilyl azide and a mixture of iodine and pyridine sequentially in dichloromethane has now been reported as a method for the preparation of p-substituted-a-iodocycloalkenones.8 The combination of iodine and pyridinium dichromate has also been reported to provide a-iodoenones from enones as well as from ethynyl carbinols.9 10 Some successes have also been achieved with enones and iodine azide (IN3)11 and iodine/ceric ammonium nitrate.12-14 The submitters first variant5 of the present procedure used carbon tetrachloride as a solvent. In this procedure this solvent has been replaced with the more benign diethyl ether. 

Ethynylarion of cyclohexanone and cycloheptanone with lithium acetylide afforded yields between 50 and 60%. Appreciable amounts of the ketones were recovered indicating an appreciable degree of enolate formation. Under similar conditions the more easily enolizable cyclopentanone gave the ethynyl carbinol in a poor (-20%) yield [2],... 

The formation of potassium acetylide is presumably an equilibrium yet it appears to be possible to convert the ketones completely into the ethynyl carbinols in greater than 90% yield, using a 1 1 molar ratio of r-BuOK and ketone. In the case of cyclohexanone even a 1 2 molar ratio gave > 85% yield of ethynylcyclohexanol, suggesting that a catalytic amount of starting base may suffice. However, the formation of acetylene diols appears to become increasingly important as the ratio r-BuOK/ketone is diminished. 

Ethynyl Ketones by Oxidation of the Corresponding Ethynyl Carbinols with Chromic Add... 

Richey [8], and then Pittman and Olah [9], observed the NMR spectra of acidic solutions of tertiary ethynyl carbinols, and their data support the idea that allenyl carbonium ions contribute significantly to the following ion structure ... 

Dimethyldiphenyl, 596, 616 Dimethyl ethyl carbinol, 260 Dimethyl ethynyl carbinol, 467, 468 P P - Dimethylglutaric acid, 876 Dimethylglyoxime, 952... 

Establishing a criterion for the purity of the product is of particular importance because of the known tendency of ethynyl-carbinols to undergo rearrangement.6 6 The authors have reported that consecutive small fractions of the distillate possess a constant boiling point and refractive index. Further, representative fractions, treated with periodic acid and subsequently with 2,4-dinitrophenylhydrazine, give cyclohexanone 2,4-dinitro-phenylhydrazone in 83% over-all yield in a high state of purity. 

Oxidation of ethynylcarbinols dihydroxyacetonyl compounds.1 This hyperva-lent iodine reagent oxidizes ethynyl carbinols to dihydroxy acetones. 

The terminal alkyne (or a propargylic alcohol, i.e. ethynyl carbinol)(l mmol) was added dropwise to a solution of BTI (516 mg, 1.2 mmol) in chloroform, or a mixture... 

The work of Nazarov on vinyl ethynyl carbinols involves condensation of vinylacetylene with ketones in the presence of caustic potash and also their conversions, many of which are catalytic in nature. A review of his work involving polymerization, isomerization, hydrogenation, and other conversions was published by him (252). Hydration of divinylacetylenes in methanol solution in the presence of mercuric sulfate and sulfuric acid gave vinyl alkyl ketones. These can be reacted with hydrogen sulfide, amines, etc., to yield heterocyclic compounds. Substituted vinyl alkyl ketones underwent spontaneous cyclization to cyclopentenones. Nazarov summarized a decade of this research in this field in 1951 (253). His general review of organic syntheses based on acetylene is also of interest in this connection (254). 

Synonym. j5-Chlorovinyl Ethyl Ethynyl Carbinol Proprietary Name. Placidyl 1 -Chloro-3-ethylpent-1 -en-4-yn-3-ol C7H9C10= 144.6 CAS 113-18-8... 

Chlorotrismethoxyphenylethylene, 45 5 Chlorotritylimidazole, 487 Chlorovinyl ethyl ethynyl carbinol, 594 Chloroxine, 650 Chloroxuron, 82 Chloroxylenol, 455 Chlorphenamine, 456 Chlorphenesin, 455 Chlorphenesin carbamate, 456 Chlorpheniramine, 456 Chlorpheniramine maleate, 457 Chlorphenothanum, 534 Chlorphenoxamine, 458... 

Ethynyl carbinols (propargylic alcohols) such as 134 (Scheme 2.58) represent another important group of oxidation level 3 compounds. Their preparation involves nucleophilic addition of acetylides to the carbonyl group, a reaction that is nearly universal in its scope. Elimination of water from 134 followed by hydration of the triple bond is used as a convenient protocol for the preparation of various conjugated enones 135. Easily prepared O-acylated derivatives are extremely useful electrophiles in reactions with organocuprates, which proceed with propargyl-allenyl rearrangements to furnish allene derivatives 136. 

The reagent adds to mos-t carbonyl compounds to form the corresponding ethynyl-carbinols in good yield. An example is the reaction with cinnamcddehyde. ... 

Ethynyl carbinols Ion-exchange resins. Phosphorus pentoxide. 

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