Diarylalkynes

The Boger group synthesis commences with a Stille coupling of a stannyl acetylene with two equivalents of a highly oxygenated bromobenzene to yield a symmetrical diarylalkyne (82). The subsequent reaction of this alkyne (82) with 3,6-dicabomethoxytetrazine under Diels-Alder/retrograde Diels-Alder... 

Complex 2 is a potent cluster precursor. The isolobal relationship (194) between diarylalkynes and the alkylidynes CpW(CO)2(=CR) is now quite well known (195). Since 2 and 3 readily add alkynes, one might reason that alkylidynes CpW(CO)2(=CR) will also add across the M=M bonds of 2 or 3. In fact, this happens, and in quantitative yield for 2, when the product is 73. The yield of 74 in the tungsten reaction is less impressive, but it is obtained in higher yield in the reaction of Cp2W2(CO)4-(fi-rf-RCCR) with CpW(CO)2(=CR). The behavior of the chromium system is quite different, the product being the /x-alkyne species Cp2-W2(CO)4(jU-i72-RCCR). Remarkably, 1 is catalytic for this dimerization (196). 

Abstract When Cp2ZrCl2 was treated with 2 equivalents of Me2PhSiLi, a zirconium-silene complex was formed. In the presence of alkyne, diarylalkyne reacted with silene coordinated with zirconium to give silazirconacyclopentene, which was hydrolyzed to give vinylsilane. On the other hand, dialkylalkyne inserted into zirconium-silene complex to give silazirconacyclopentene, which was hydrolyzed to give allylsilane. Formation of the zirconium-silene complex was monitored by H NMR spectra. 

A Suzuki coupling of 2,6-dimethoxyiodobenzene with the dihydroaromatic boron compound 13 forms the basis of a synthesis of the dibenzo[6,t/]pyran ring system <03AG(E)2795> and naphtho[2,3-c]chromenes result from an intramolecular dehydro DA reaction on the diarylalkynes 14 <03SL1524>. 

The dinuclear hydridorhodium complex [ ( x-H)Rh P(0— Pr )3 2 2] is a catalyst for the stereoselective hydrogenation of dialkylalkynes and diarylalkynes to the corresponding rrans-alkenes. Although the hydrogenation rates are much lower than for terminal alkenes (approximately 1 turnover... 

Sodium hydride can be used as a dehydrohalogenadng agent in dipolar aprotic solvents, such as DMSO or HMPA. Halostilbenes have been converted to the corresponding diarylalkynes in this way. ... 

Organolithium compounds can also induce the rearrangement of 1,1-diaiyl vinyl dichlorides and dibromides (Fritsch-Buttenberg-Wiechell rearrangement) to diarylalkynes p,p -bridged cyclic diaiylal-kynes ° can be prepared via this route (Scheme 59). 

Addition of phthalimidesulfenyl chloride to both diarylalkynes and alkyl(aryl)al-kynes affords sulfenamldes as a mixture of the Markovnikov and anti-Markonikov... 

Mouries, V.. Waschbiisch, R., Carran, J., and Savignac, P, A facile and high yielding synthesis of symmetrical and unsymmetrical diarylalkynes using diethyl dichloromethylphosphonate as precursor. Synthesis. 271. 1998. 

Metathesis. Diarylalkynes are prep Mo(CO)fi and p-chlorophenol at 140 ynyl)pheny]siloxanes form cyclotrimers aw... 

Metathesis. Diarylalkynes are prepared from 1-arylpropynes on heating with Mo(CO)5 and p-chlorophenol at 140°. Under the same conditions, bis[4-(prop-l-ynyl)pheny]siloxanes form cyclotrimers and cyclotetramers.- ... 

Silyl ketones behave differently. While aliphatic silyl ketones are reduced to a-silyl alcohols, aromatic congeners give l,2-diarylalkynes. In the presence of MejSiCl, the purported oxaytterbiacyclopropane intermediate can be trapped. Yet another pathway appears when the reaction is conducted in the presence of another ketone. A tandem deoxygenation-acylation reaction occurs with the silyl ketones donating the acyl moieties. ... 

A study of the photochemical addition of diarylalkynes (279) to the quinone (280) has shown that the quinone methides (281) are formed. As is well known, the addition involves the formation of an oxetene (282) that ring opens. There is some degree of selectivity when non-symmetric alkynes are used as indicated by results shown beside the appropriate structures. The photochemical reaction can be brought about either by irradiation at wavelengths >410 nm or by irradiation into the charge transfer band at wavelengths > 530 nm. The outcome is the same... 

Diarylalkynes The anion (1) of this diazo compound, prepared with n-butyllithium (or potassium t-butoxide) in THF at low temperatures, converts diaryl ketones into diarylalkynes in high yield (equation I). Heteroaromatic ketones behave in the same way, but only very electrophilic aryl aldehydes... 

Dialkyl-l-tetralones, 240 Pic-Diamines, 206 Diarylalkynes, 188-189 Diaryl a-difcetones, 200 Diarylmethanes, 366,473... 

A series of benzil derivatives related to combretastatin A-4 have been synthesized by the oxidation of diarylalkynes promoted by Pdl2 in DMSO (Figure 8.5) [56]. Several benzils exhibited antiproliferative activity and inhibited cell growth of four... 

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