Ethynylzinc chloride

The application of the ketone synthesis has continued. Phenylethynyl and vinylethynyl ketones have been synthesized by the reaction of appropriate acid halides with phenylethynylzinc chloride 521, 522) and vinyl-ethynylzinc chloride 552), respectively. 

Ethynylzinc chloride was prepared as described above. To this were added sequentially at 0 °C 4.68 g (20 mmol) of p-iodoanisole (2) dissolved in THF (20 mL) and 1.15 g (1.0 mmol) of Pd(PPh3)4 in THF (20 mL). The reaction mixture was stirred for 1 h at 25 °C. GLC examination of an aliquot of the reaction mixture after quenching indicated the formation of the title compound, essentially as the only volatile product. The remainder of the reaction mixture was... 

Mg acetylides are easily prepared and used for coupling. A good preparative method of 1-alkynes is the coupling of commercially available ethynylmagnesium chloride (122) or ethynylzinc chloride (123) as acetylene surrogates with aryl or alkenyl halides. Their couplings with halides directly afford the 1-alkynes 124. No deprotection is necessary [60]. 

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