Aryl acetylides

Benzofurans have also been prepared by the coupling of o-halogeno-phenols with cuprous aryl acetylides and ensuing cyclization of intermediate diarylacetylides134-136 (Scheme 74). 

The same group has also investigated alkyl and silyl acetylides, as opposed to the aryl acetylides of most of the other studies. The a-donor strength of the... 

These conclusions have been reinforced by at least two recent, detailed theoretical studies using TD-DFT calculations [87,88], which reveal that the proportion of Pt(5d) metal character in the HOMO falls from around 25% for alkyl acetylides (R = n-propyl) to around 10% for phenylacetylide, the tt(C=C-R) character increasing correspondingly. For an aryl acetylide with... 

Fig. 1-26. Carbonylative aryl-acetylide coupling catalyzed by [Pd(dppl)].

The obtained aminosilane-substituted aryl acetylides were treated with HCI to convert the amino groups into reactive chloro functions (Eq. 4). Furthermore, the resulting chloro-frmctionalized products can be used for the next steps in order to build up porous solid structures. For this purpose some chloro positions can be protected by diethylamine again (Eq. 4). 

We have widened our scope in the current work to form a new series of platinum aryl-acetylide polymers and their dinuclear counterparts containing 0, S, SO, and SOj functional groups. These are remarkable model systems that can be used to evaluate how chalcogen-based conjugation-interrupters would limit the effective conjugation length of polymetallaynes. 

Oxidative coupling of acetylenic compounds proceeds more eflBciently in the solid state than in water. In this procedure, powedered cuprous aryl acetylide and CUCIJ.2H2O was kept for 3 hr to give the coupled product in 40-75% yield (Scheme 35), compared to 10-30% in water. 

Hurst SK, Ren T (2002) Synthesis, characterization and electrochemistry of diruthenium complexes linked by aryl acetylide bridges. J Oiganomet Chem 660 1-5... 

More recently, the same group found that alkynyl aluminum reagents undergo conjugate addition to cyclic enones in the presence of chiral Ni-bisphosphine complexes [55]. They found that the use of binol-based phosphine L9 provides high yields and enantioselectivities (up to 90% ee) for a broad range of cyclic enones. Interestingly the scope of the reaction is not limited to TMS-protected acetylides but it can be extended to aryl-acetylides (Scheme 10). 

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