Synthesis of substituted anthracenes, pentaphenes and trinaphthylenes via alkyne-cyclotrimerization reaction

Indium-Catalyzed Construction of Polycyclic Aromatic Hydrocarbon Skeletons via Dehydration

“…Treatment of 2-benzylbenzaldehyde ( 1a ) with a catalytic amount of indium salt In(OTf) 3 in toluene at 115 °C for 24 h resulted in cycloaromatization to produce anthracene ( 2a ) in 94% yield (eq ) . Scandium triflate, Sc(OTf) 3 , and a rhenium complex, [ReBr(CO) 3 (thf)] 2 , also showed high catalytic activity in toluene; however, a higher reaction temperature was necessary to complete the reaction (150 °C, 24 h: Sc(OTf) 3 , 93%; [ReBr(CO) 3 (thf)] 2 , 97%). − Several other Lewis acids also showed catalytic activity under varying conditions. Conditions A (toluene, 150 °C, 24 h): Sc(OTf) 3 , 93%; [ReBr(CO) 3 (thf)] 2 , 97%; ReBr(CO) 5 , 82%; Re 2 (CO) 10 , 0%; MnBr(CO) 5 , 0%; Mn 2 (CO) 10 , 0%; FeCl 3 , 8%; [IrCl(cod)] 2 , 2%; Cu(OTf) 2 , 74%; AgOTf, 63%; InCl 3 , 97%; In(OTf) 3 , 97%; Bi(OTf) 3 , 71%.…”

Recent advances in the syntheses of anthracene derivatives

“…The authors converted the resulting benzylic alcohols 29 to the corresponding aldehydes by treatment with PCC/Celite in dichloromethane (DCM). Finally, treatment with a catalytic amount of CF 3 SO 3 H provided the corresponding anthracenes 30a – c in good yields (57–75%) [ 40 ].…”

“…This methodology was notable for being an alternative method to synthesize 2,3,6,7-halogenated anthracene derivatives, which are difficult to obtain. In 2010, Okamoto et al published a three-step procedure to synthesize substituted anthracenes, pentaphenes, and trinaphthylenes via a [2 + 2 + 2] alkyne-cyclotrimerization reaction catalyzed by a cobalt/zinc reagent [40]. With regard to substituted anthracenes, this method consisted of a [2 + 2 + 2] cycloaddition reaction of 1,6-diynes 27 with 4-aryl-2-butyn-1-ols 28 (Scheme 6).…”

Cobalt-Catalysed Bond Formation Reactions; Part 2

“…Investigations were directed towards the synthesis of functionalised arenes, such as various halo-and bromofunctionalised arenes (136), 259 boron-functionalised arenes (137) 260 and other functional groups prone to polymerisation reactions. 261,262 Also, investigations for the synthesis of extended polycyclic materials, 263 such as 138, star-like polyarenes, 264 or chiral helicenes, 265,266 were reported. Intermolecular cyclotrimerisations of terminal alkynes to trisubstituted arenes (139) [267][268][269] as well as cyclotrimerisations of internal alkynes 270 were investigated to control the regiochemistry of the products, such as 140, formed.…”