Acetylenic compounds, triphenyl

SCHEME 47.35. owil-Diaddition of triphenyl phosphite to acetylenic compound. 

Stable derivatives of diallgrl 2-(dialko3g hosphoryl)succinates (250) and (252) have been prepared in water, in good yields using multicomponent reactions involving activated acetylenic compounds (249), trimethyl phosphite or triphenyl phosphate, l-(6-hydro3y-2-isopropenyl-l-benzo-furan-yl)-l-ethanone (248) or 4-hydro3Q coumarin (251) (Scheme 89). °... 

Catalytic forms of copper, mercury and silver acetylides, supported on alumina, carbon or silica and used for polymerisation of alkanes, are relatively stable [3], In contact with acetylene, silver and mercury salts will also give explosive acetylides, the mercury derivatives being complex [4], Many of the metal acetylides react violently with oxidants. Impact sensitivities of the dry copper derivatives of acetylene, buten-3-yne and l,3-hexadien-5-yne were determined as 2.4, 2.4 and 4.0 kg m, respectively. The copper derivative of a polyacetylene mixture generated by low-temperature polymerisation of acetylene detonated under 1.2 kg m impact. Sensitivities were much lower for the moist compounds [5], Explosive copper and silver derivatives give non-explosive complexes with trimethyl-, tributyl- or triphenyl-phosphine [6], Formation of silver acetylide on silver-containing solders needs higher acetylene and ammonia concentrations than for formation of copper acetylide. Acetylides are always formed on brass and copper or on silver-containing solders in an atmosphere of acetylene derived from calcium carbide (and which contains traces of phosphine). Silver acetylide is a more efficient explosion initiator than copper acetylide [7],... 

Alkali metal alkyls, particularly n-butyl lithium, are the most frequently used reagents to form metallated intermediates.246 247 In certain cases (di- and triphenyl-methane, acetylene and 1-alkynes, cyclopentadiene) alkali metals can be directly applied. Grignard reagents are used to form magnesium acetylides and cyclopenta-dienyl complexes.248 Organolithium compounds with a bulky alkoxide, most notably M-BuLi-ferf-BuOK in THF/hexane mixture, known as the Lochmann-Schlosser reagent or LICKOR superbase, are more active and versatile reagents.249-252... 

Trismbslitmted okfias. The reagent adds stereospedfically to dimethyl acetylene-dicarboxylate (DADC) to give the ri.r-vinylrhodium(l) compound (2). This reacts with neat methyl iodide at 25 (30 min.) to give dimethyfiodocarbonylbi (triphenyl-... 

The first step in the preparation of a cyclopropenium salt is usually the addition of a carbene to an acetylene to provide a cyclopropane derivative. The carbene may come from decomposition of a diazo-compound, as in the example given at the beginning of this chapter [1], or alternatively by treatment with base of a suitable chioro-compound. Thus an alternative preparation of a triphenyl-cyclopropenium salt proceeded as follows [15] ... 

Acetylenes may frequently be trimerized by treatment with triphenyl- or trialkyl-chromium compounds to give substituted benzenes and bis-w-arene chromium complexes. The course of the reaction depends on the stoicheiometry of the reaction mixture. Figure 50 illustrates the possible mode of formation of the benzene derivatives. The complex Me2Co(PPh3)7r-CjH5 can catalyze the trimerization of acetylene itself to give benzene. 

---