Ethynyl compounds

The orally active progestational agent 17a-ethynyltestosterone (56) was subsequently obtained by Oppenauer Oxidation. Similarly ethynyla-tion of 3-ethoxyandrosta-3,5-dien-17-one followed by acid hydrolysis afforded the 17a-ethynyl compound (56). ... 

The 17a-ethynyl compound (59) has been prepared in 88% yield from estr-4-ene-3,17-dione (58) and acetylene, at 2-3 atm pressure in tetrahydro-furan in the presence of potassium t-butoxide. Presumably the A-ring enone system is protected as the enolate anion during the course of the reaction. 

Ethynylation of 3j -hydroxy-16a-methyl-5a-androstan-17-one in a mixture of diethylene glycol dimethyl ether and diethylene glycol monoethyl ether in the presence of potassium hydroxide produces two isomeric 17-ethynyl derivatives. This result is not unexpected since molecular models suggest that the steric influence of the 13/ -methyl group is nearly offset by the 16a-methyl group. The presence of a 16a-acetoxy group in the estrone series also leads to the formation of epimeric 17-ethynyl compounds (61) and (62) on reaction with acetylenedimagnesium bromide. 

The 13-ethyl-17-ketones, i.e., (63), have been found to be considerably less reactive than their 13-methyl counterparts towards acetylenic nucleophiles. The difference is attributed to the additional steric hindrance provided by the ethyl group. An attempt to introduce an ethynyl group into mc- 2>-isopropyl-3-methoxygona-l,3,5(10)-trien-17-one was unsuccessful even in ethylenediamine at 50°. However ethynylation of rac-13-isopropyl-3-methoxygona-1,3,5(10),8(14)-tetraen-17-one proceeded smoothly at room temperature to afford the 17a-ethynyl compound in 60% yield. ... 

Oppenauer oxidation of the enol ether (34) affords the corresponding 17 ketone (37) (the enol ether is stable to the basic oxidation conditions). This ketone affords the corresponding 17a-ethynyl compound on reaction with metal acetylides. Hydrolysis of the enol ether under mild conditions leads directly... 

Decarboxylations of organotin and -lead propiolates do not yield the expected ethynyl compounds, R3MC=CH, but the dimetallated acetylenes R3MC=CMR3 (M = Sn or Pb, R = Ph) are obtained (53,54). The disproportionation reaction [Eq. (39)] is thought to follow decarboxylation [Eq. (38)]. Independently synthesized ethynyltriphenyltin has been observed to undergo disproportionation [Eq. (39), R = Ph, M = Sn] at room temperature (55). 

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... 

Oppenauer oxidation of the enol ether (34) affords the corresponding 17 ketone (37) (the enol ether is stable to the basic oxidation conditions). This ketone affords the corresponding 17a-ethynyl compound on reaction with metal acetylides. Hydrolysis of the enol ether under mild conditions leads directly to ethynodrel (39), an orally active progestin. This is the progestational component of the first oral contraceptive to be offered for sale. Treatment of the ethynyl enol ether with strong acid leads to yet another oral progestin employed as a contraceptive, norethindrone (40). ° In practice these and all other so-called combination contraceptives are mixtures of 1-2% mestranol... 

Conversion of Ethynyl Compounds into Solutions or Suspensions of the Alkali Acefyiides in Liquid Ammonia... 

In the case of the platinum ethynyl compound om.l, for which = 360 nm, a broad 2PA band was observed around 630 nm, with 3max 3.0xl0 GM [162,163]. In dendritic-type compounds containing multiple metal centers but still with phenylene ethynylene ligands, larger 2 PA cross sections were reported. For example, om.3 displays 3max 3.5 x 10 GM for the peak at 740 nm, but no 2PA activity was detected into the lowest one-... 

The observed product distributions reflect the influence of both factors. In the parent compound 102 and in the silyl substituted 104, the initially formed open-chain silylenes 103 and 146 are relatively sensitive and the migration tendency of the group R is quite large, and therefore the silacyclopropenylidenes 104 and 145 are found. In contrast, the methyl and the ethynyl compound 138 and 150 are stable enough to pass the pyrolysis tube and both can be matrix-isolated upon pyrolysis of the appropriate precursors 137 and 149. Due to the small migration tendencies of the methyl and the ethynyl group, the rearrangement product 135 is not found at all and 151 is detected only in relatively minor amounts. 

Since there is almost no side-reaction in the polycondensation between metal halides and a, polymers with a degree of polymerization which is nearly equal to that predicted theoretically and base on the monomer ratio, e.g. (31)/(32) in Eq. 11, are obtained. For example, the polycondensation of the system composed of the monomers (PBu3)2 PtCl2 and... 

Reaction of a protected acetylene, e.g. 2-methylbut-3-yn-2-ol, with 2,3-dichloroquinoxaline has been found to give mono- or disubstituted products according to the equivalents used treatment of the products with dry sodium hydroxide in toluene gives the corresponding ethynyl compounds. ... 

Formation of diphenyldiacetylene by the oxidation of the copper(i) salt of phenylacetylene was observed by Glaser over a century ago . The modern refinement of the reaction involves shaking an ethynyl compound with an aqueous... 

It is sometimes necessary to protect active sites of acetylenic compounds to achieve the desired reactions. Acetylenic compounds that have an active hydrogen tend to react with heavy-metal salts to form explosive metal acetylides. However, when treated with potassium mercuric tetraiodide or mercuric acetate in organic amines, monosubstituted terminal ethynyl compounds give stable crystalline mercuric salts. These mercuric salts can be purified by recrystallization in organic solvents and used for identification. They can be further converted to lithium acetylides, which are useful tools for chemical synthesis [Eq. (62) 156]. 

Alkylmercuric halides react analogously with ethynylmagnesium bromide, yielding alkyl(ethynyl) compounds of the type RHgC=CH.171... 

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). 

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