Platinum hydroarylation

PLATINUM CATALYZED HYDROSILYLATION AND PALLADIUM CATALYZED CROSS-COUPLING ONE-POT HYDROARYLATION OF 1-HEPTYNE TO (E)-l-(l-HEPTENYL)-4-... 

Fig. 2.18 PaUadium and platinum NHC complexes as catalysts in hydroarylations of alkynes...

Cyclization process of arene-yne substrates has been reported with platinum(rv) catalyst (PtCL ), resulting in C-H activation and functionalization.142 This hydroarylation gives 6-< r/o-products in high yields with good tolerance to different functional groups like amine, ester, and ether. This method provides a rapid access to interesting molecules such as coumarins, chromenes, or dihydroquinolines. 

The intramolecular hydroarylation of alkynes is a useful method for the synthesis of fused arenes. For example, biphenyl derivatives, bearing an alkyne unit at the ortho position, were converted into substituted phenanthrene derivatives in the presence of various jc-electrophihc transition metal catalysts such as platinum, palladium, gold, gaUium, indium, iron, and so on (Scheme 21.48) [54]. 

The sequential intramolecular hydroarylation of alkynes has been applied to the catalytic helicene synthesis. The platinum-catalyzed sequential intramolecular hydroarylation of diynes proceeded to give substituted [6]hehcenes (Scheme 21.50) [56]. 

Using the results of previous studies of palladium- and platinum-catalyzed hydroarylation of alkynes (Fig. 26A), Kitamura and coworkers extended this chemistry to functionahze PS and polystyrene-l)/ocfe-poly(ethylene-ra -butylene)-l>/ocfe-polystyrene (SEES) with acrylic acid moieties (Fig. 26B). Reactions of PS with propionic acid or methyl ester in the presence of K2PtCl4 and Ag(CF3S03) afforded maximums of 7% and 30% alkenylated styrene unit for PS and SEES, respectively. Although... 

Figure 26 (A) Palladium- or platinum-catalyzed hydroarylation of alkynes and (B) platinum-catalyzed alkenylation of PS and SEBS.

Hashimoto T, Iguchi N, Oyamada J, Kitamura T. Direct functionalization of polystyrenes by platinum(II)-catalyzed hydroarylation. A new methodology for utilization of... 

Indole derivatives tethered by alkenyl or allenyl groups undergo efficient intramolecular hydroarylation. Treatment of 2-(4-pentenyl)indoles with a catalytic platinum/chiral phosphine complex induced intramolecular hydroarylation to give tetrahydrocarbazole in 93% yield with 90% ee (Scheme 18.14) [13], The similar intramolecular asymmetric hydroarylation was applied to indoles having internal olefins by use of a highly strained planar chiral platinacycle (Scheme 18.15) [14],... 

A platinum-catalyzed intramolecular hydroarylation of ethyl 2-benzyl-2,3-alkadienoates afforded an efficient synthesis of 1,4-dihydronaphthalenes having various alkyl groups on the 4-positions and/or ethoxycarbonyl group on the 2-position, through 6-endo cyclization (Scheme 18.20) [19]. The same Pt-catalyzed hydroarylation of ethyl 2-phenethyl-2,3-butadienoate gave a seven-membered product in 64% yield. 

A total synthesis of 6-deoxyclitoriacetal, a cyctotoxic natural product, was achieved using platinum-catalyzed intramolecular hydroarylation of a propargyl aryl... 

The chromene synthesis via intramolecular hydroarylation was applied to a total synthesis of ( )-deguelin, which was shown to be an efficacious chemopreven-tive agent for both in vitro and in vivo models (Scheme 18.55) [45]. A key step involves platinum-catalyzed 6-endo hydroarylation of the alkynone derived from 3,4-dimethoxyphenol in three steps. The intramolecular hydroarylation of alkynone... 

Hashmi and coworkers found that intramolecular fi-alkenylated furan product, polyheterocycle 4,5,6,7-tetrahydrofuro[2,3-c]pyridine derivatives 127 rather than phenolic products [59], could be efficiently constructed via gold(I)-catalyzed aco-selective intramolecular hydroarylation of silylated y-alkynylfurans 126 (Scheme 12.55) [60]. Substrates bearing different silylated groups have a different reactivity. They also found that gold(I) catalyst efficiently serves as a hydroarylation catalyst for the silylated y-alkynylfurans, while the platinum(II)... 

In 2012, Van der Eycken and coworkers realized a regioselective synthesis of pyrrolopyridinones 137 and pyrroloazepinones 138 (Scheme 12.60) [64]. They employed an Ugi reaction, which is followed by a gold(I)- or platinum(ll)-catalyzed intramolecular hydroarylation. The method allows the selective formation of six- and seven-membered pyrrole-fused heterocycles from easily available starting materials under mild reaction conditions. 

Biffis A, Tubaro C, Buscemi G, Basato M. Highly efficient alkyne hydroarylation with chelating dicarbene paUadium(II) and platinum(II) complexes. Adv Synth Catal. 2008 350 189-196. 

Recently, Barluenga and Fananas reported tandem intramolecular hydroaUc-oxylation/hydroarylation and hydroaUcoxylation/Prins-Type annulation reactions. In the first communication, they described the cycloisomerization of 5-alkynols with several gold, platinum, and silver catalysts and the application to the synthesis of enantiopure benzo fused cyclic ethers from the chiral pool [150] (Scheme 87). 

Toullec PY, Chao C-M, Chen Q, Gladiali S, GenSt J-P, Michelet V (2008) Enantioselective platinum-catalyzed tandem hydroarylation-cycloisomerization of 1,6-enynes. Adv Synth Catal 350 2401-2408... 

---