Ethynyl groups compounds

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. ... 

Replacement of the para-substituted phenyl unit of alternating phosphine-ary-lene polymers by an ethynyl group, gives rise to a new family of 71-conjugated materials. Indeed, compounds (77) and (78) were prepared in 53% and 3% iso-... 

Fig. 3. Known and hitherto elusive perethynylated building blocks for two- and three-dimensional acetylenic scaffolding. The only compounds shown are those with either free or silyl-protected ethynyl groups...

While the topic of purely organic carbon-rich compounds has attracted quite a number of different groups, the organometallic arm of the enterprise has, with some exceptions [11b, d], been much less developed until recently. This is due to the anticipated synthetic difficulties and supposed lack of stability in synthesis and manipulation of ethynylated organometallic compounds. Both of these concerns can be obviated, if the target molecules, such as 2 and 3, are chosen carefully. 

Analogous reactions were postulated to occur for 17a-ethynylestradiol and, on the basis of experiments with model compounds, oxidation of the ethynyl group to -COCHO (Huber et al. 2004). 

Elaboration of a commercially viable route for total synthesis of 19-nor steroids led to the introduction of the totally synthetic product norgestrel (71) as the progestational component of an oral contraceptive. As was observed in the "natural" 19-nor-compounds, reduction of the 17-ethynyl group to 17-ethyl affords compounds with androgenic/anabolic... 

Compounds presented in Scheme 9 have provided evidence for the influence of the otherwise rarely investigated />-anilino-ethynyl group and a variety of auxiliary ligands on the luminescence, NLO, and mesogenic properties of this type of complexes.98... 

Altoff, W., Fild, M., Rieck, H.-R, and Schmutzler, R., Synthesis and NMR spectroscopic studies of phosphorus compounds with vinyl and ethynyl groups, Chem. Ber., Ill, 1845, 1978. 

Attempts to elucidate the polymerization or copolymerization kinetics of ethynyl and maleimide-functionalized monomers have been undertaken via vibrational spectroscopy (137). The thermal polymerization of A-(3-ethynyl-phenyl) maleimide (the structure is given in Fig. 48) was studied via IR and Raman spectroscopy. This model compound is interesting because it carries maleimide and ethynyl groups attached to the same aromatic ring. Kinetic studies indicate that both the acetylene and maleimide group react at the same rate, which strongly suggests the formation of a copolymer rather than a mixture of homopolymers. 

The thin control of the energetic characteristics and the electronic transition nature may be carried out by chemical structure alteration. For example the appearance of CH2 group between phenyl ring and triple bond (compounds 3 and 5 in Table 4) interrupts the interaction between it-ekctrons of the both elements. This leads to the short wavelength shift in the absorption and photoconductivity spectra. The insertion of the ethynyl group instead of a CH2 group restores the conjugation. The increase in the numbers and sizes of the... 

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. 

The reaction of alkyl phenylethynyl telluriums with alkyl lithium compounds or alkyl magnesium bromides in diethyl ether at 20° leads to the replacement of the ethynyl groups by alkyl groups2. The yields in these reactions range from 68 to 95%. 

Vinyl and ethynyl groups attached to an imidazole ring can be catalytically reduced to the saturated (or less unsaturated) species and cleaved by oxidation. The corresponding 4-carbaldehyde is formed in 71% yield when l-methyl-2,5-diphenyl-4-styrylimidazole is oxidized with osmium tetroxide. However, they may not react like aliphatic alkenes and alkynes not all addition reactions occur normally, Michael additions are known, and the compounds can act as dienophiles in DielsAlder reactions (e.g., Scheme 132). 

Ethynylcopper compounds are known to be polymeric. X-ray diffraction analysis indicated that they are composed of infinite zigzag chains of copper atoms, each bound to three ethynyl group by a- and 7r-bonds... 

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