Phenylethynylmagnesium bromide

Coupling of terminal acetylenes (2,91, ref. 17a). The cuprous chloride-catalyzed coupling of phenylethynylmagnesium bromide with propargyl bromide to form I -phenyl-1,4-pentadiyne has now been published.12... 

This means that a Grignard reagent prepared, say, from p-bromophenylacetylene (1) and magnesium will rearrange spontaneously to phenylethynylmagnesium bromide the aryl functional position is thus destroyed and the reaction site is transferred to the terminal ethynyl position. 

Reaction of (380) with phenylethynylmagnesium bromide gives two products which were shown to be (381) and (382) spectroscopically. The assignment of configuration to (381) and (382) was based upon the quantitative thermolysis of one of the two, (382), to (383). Upon thermolysis of (381), an intermediate was obtained which was very susceptible to oxidation. In the presence of oxygen, (385) and (386) were isolated, but the details of their formation have... 

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