Organophosphorus compounds, 155 - 1,2-additions of organomagnesium halidesto phosphaalkynes: Synthesis of 2-phospha-1-vinylmagnesium halides and a novel type of magnesium-phosphorus cage compound

Grignard reagents such as isopropyl- and tert-butylmagnesium halide (2a: X = Cl; 2b: X = Br) react with tert-butylphosphaacetylene (1) in a regio- and stereoselective 1,2-addition process at -78 degreesC to give the 2-phospha -1-vinylmagnesium halides 3a,b in high yields. At elevated temperatures, th e phosphavinylmagnesium chloride 3a reacts with two more equivalents of 1 t o afford the previously unknown magnesium-phosphorus cage compound 4, the s tructure of which has been confirmed by X-ray-analysis.