L-chloro-2-phenylacetylene

A combination of Co-mediated amino-carbonylation and a Pauson-Khand reaction was described by Pericas and colleagues [286], with the formation of five new bonds in a single operation. Reaction of l-chloro-2-phenylacetylene 6/4-34 and dicobalt octacarbonyl gave the two cobalt complexes 6/4-36 and 6/4-37 via 6/4-35, which were treated with an amine 6/4-38. The final products of this domino process are azadi- and azatriquinanes 6/4-40 with 6/4-39 as an intermediate, which can also be isolated and separately transformed into 6/4-40 (Scheme 6/4.11). 

Preparation of l-Chloro-2-phenylacetylene from Lithium Phenylacetylide and Chlorine... 

To a solution of copper chloride (2.4 mg, 0.024 mmol) in DMF (1.5 ml) was added l-chloro-2-phenylacetylene (50 mg, 0.37 mmol) at r.t. To the mixture was added trimethyl(4-methoxyphenylethynyl)silane (50 mg, 0.25 mmol). The reaction mixture was stirred for 48 h at 80 °C, quenched with 3 M HCl, and extracted with diethyl ether (25 ml x 2). The combined ethereal layer was washed with aqueous NaHCOj solution, then with brine and dried over MgS04. Filtration and evaporation provided a brown oil. Purification by column chromatography (Si02, hexane dichloromethane = 10 1) gave l-(4-methoxyphenyl)-4-phenyl-1,3-butadiyne (36 mg, 65% yield) as a colorless solid. 

Substituted polyacetylenes usually show a softening point in the range of ca. 200 to 400 °C (Table 27). It should be noted that these softening points are higher than those of usual vinyl polymers. Poly(l-chloro-2-phenylacetylene) does not melt but only decomposes (dehydrochlorinate) at high temperature. It is known that polyacetylene isomerizes at 145 °C from cis to trans and undergoes an exothermic reaction at 325 °C, but does not melt below 400 °C during its differential thermal analysis 9S). 

The polymerization procedures are the same as those of l-chloro-2-phenylacetylene. 

Fig, 10.6 Composition curves for the copolymerizations of 1-chlorodec-l-yne (Mi) with (a) dec-2-yne and (b) l-chloro-2-phenylacetylene (M2), catalyzed by MoCl5/Bu4Sn (1/1) in toluene at 30°C (Masuda 1987b). 

Example 19 Polymerization of l-Chloro-2-phenylacetylene with a Mo(CO)6-Based Catalyst... 

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