Propyne 1-phenyl

On the other hand, its cycloadditions with 1,2-disubstituted alkenes under similar conditions produce stereospecifically a mixture of regioisomeric products [35] (equation 34) In contrast, its reaction with theunsymmetrical alkyne 1 -phenyl-propyne leads to a single product [35] (equation 35)... 

The regiochemistry of Al-H addition to unsymmetrically substituted alkynes can be significantly altered by the presence of a catalyst. This was first shown by Eisch and Foxton in the nickel-catalyzed hydroalumination of several disubstituted acetylenes [26, 32]. For example, the product of the uncatalyzed reaction of 1-phenyl-propyne (75) with BujAlH was exclusively ds-[3-methylstyrene (76). Quenching the intermediate organoaluminum compounds with DjO revealed a regioselectivity of 82 18. In the nickel-catalyzed reaction, cis-P-methylstyrene was also the major product (66%), but it was accompanied by 22% of n-propylbenzene (78) and 6% of (E,E)-2,3-dimethyl-l,4-diphenyl-l,3-butadiene (77). The selectivity of Al-H addition was again studied by deuterolytic workup a ratio of 76a 76b = 56 44 was found in this case. Hydroalumination of other unsymmetrical alkynes also showed a decrease in the regioselectivity in the presence of a nickel catalyst (Scheme 2-22). 

Photolysis of acyldisilanes at A > 360 nm (103,104) was shown, based on trapping experiments, to yield both silenes 22 and the isomeric siloxy-carbenes 23, but with polysilylacylsilanes only silenes 24 are formed, as shown by trapping experiments and NMR spectroscopy (104,122-124) (see Scheme 4). These silenes react conventionally with alcohols, 2,3-dimethylbutadiene (with one or two giving some evidence of minor amounts of ene-like products), and in a [2 + 2] manner with phenyl-propyne. Ketones, however, do not react cleanly. Perhaps the most unusual behavior of this family of silenes is their exclusive head-to-head dimerization as described in Section V. More recently it has been found that these silenes undergo thermal [2 + 2] reactions with butadiene itself (with minor amounts of the [2 + 4] adduct) and with styrene and vinyl-naphthalene. Also, it has been found that a dimethylsilylene precursor will... 

The kinetics and stereochemistry of addition of HC1 to 1-phenyl-propyne and to 3-hexyne in acetic acid have been found to be different in the two cases (4 and 5 of Table 2) (Fahey and Lee, 1966,1967,1968). 

Another option for Sonogashira coupling as an initiator of sequential catalysis is the coupling isomerization reaction (CIR) of electron-deficient halide and 1-aryl propargyl alcohols giving rise to the formation of chalcones [115, 116]. Based upon the CIR of electron-deficient halides 163 and l-(p-bromo phenyl) propyn-l-ol (164) Muller and Braun [117] presented a consecutive... 

Under forcing conditions, 1-phenylpropyne can be much more highly lithiated. The greatest substitution was obtained by heating 1-phenylpropyne neat with a 50-fold excess of n-BuLi at 75° to 85° C for 48 hours. Quenching with D20 produced a mixture of deuterated 1- and 3-phenyl-propynes, which was studied by mass spectroscopy. The isomer distribution is shown in Table III. 

Acetoxy-2-phenyl propyne 3-Acetoxy-3-phenylbut-l -enoic acid-2 50 [429]... 

H-pyran synthesis from, 3, 759 Propyne, 3-(2-amino-1 -benzimidazolyl)-isomerization, 5, 450 Propynoic acid, phenyl-ethyl ester... 

The stereochemistry of the addition of phosphorus pentachloride to isolated acetylenes in non-polar solvents has been shown by n.m.r. to be CIS, as illustrated for the adduct (46) from propyne. This observation has been explained in terms of a four-centre process. Contrary to a previous report, the reaction of triphenylphosphine hydrobromide with phenyl-acetylene carboxylic acid (47) yields both the trans- and the known c/5-adducts. 

Figure 6-11. 1 -H-Benzotriazole, 2,5-bis(N-pyridyl)-1,3,4-oxadiazole, cyclohexylammonium benzoate, benzylsulfonylacetic acid, 2,4-diamino-6-mercapto pyrimidine, hydroxamic acid, 3-phenyl-2-propyn-1-ol, dicyclopentadiene dicarboxylic acid.

F. B. Growcock and V. R. Lopp. The inhibition of steel corrosion in hydrochloric acid with 3-phenyl-2-propyn-l-ol. Corrosion Sci, 28(4) 397-410,1988. 

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