Asymmetric Synthesis of Isoindoline and Isoquinoline Derivatives Using Nickel(0)-Catalyzed [2 + 2 + 2] Cocyclization

Synthesis of Biaryls via Palladium‐Catalyzed [2+2+2] Cocyclization of Arynes and Diynes: Application to the Synthesis of Arylnaphthalene Lignans

“…A C H T U N G T R E N N U N G (acac) 2 , PPh 3 , and DIBAL-H, [3] the desired product 1aa or 1ab was not produced, and a complex mixture containing some polymerization products was obtained (runs 1 and 2). Thus, the catalyst was changed from nickel(0) to palladium(0) [5][6][7] (runs [3][4][5][6][7][8][9].…”

“…Thus, the catalyst was changed from nickel(0) to palladium(0) [5][6][7] (runs [3][4][5][6][7][8][9]. The reaction of 3a and aryne precursor 2'a in the presence of CsF in CH 3 CN at room temperature was again investigated using Pd 2 dba 3 as a catalyst, and the desired product 1aa was obtained in 18 % yield (run 3).…”

“…It is known that an alkyne having an electron-withdrawing substituent is more reactive than that having no or an electron-donating substituent for Ni(0)-or Pd(0)-catalyzed [2 + 2 + 2] cocyclization, which is consistent with the results of runs 3 and 4. [3,10] Next, ligand effects in the reaction of 3b and 2'a under similar conditions were investigated (runs 5-7), and it was found that PA C H T U N G T R E N N U N G (o-tol) 3 is suitable for this reaction and that the yield of 1ab was greatly improved to 73 % (run 7). The reaction of 3c, having an aldehyde on the alkyne, with 2'a gave the desired product 1ac in only 2 % yield along with a complex mixture of polymerization products as a major product (run 8).…”

“…Following the similar procedure for 3a, the crude product, which was prepared from the carboxylic acid (410 mg, 1.6 mmol), the propargylic alcohol 18b [19] (236 mg, 2.1 mmol), DMAP (58.6 mg, 0.48 mmol), and DCC (528 mg, 2.6 mmol) in CH 2 Cl 2 (8.0 mL) at room temperature for 1.5 h, was purified by column chromatography on silica gel (hexane/AcOEt = 10/1) to give 3l as a yellowish oil; yield: 283 mg (50 %); IR (neat): n = 3 (40 mol % to substrate diyne), and CsF (dried under vacuum at 100 8C for 2 h just before its use, 6.0 equivs. to substrate diyne) in degassed CH 3 CN (0.04 M to Pd catalyst) was stirred at room temperature for 20 min.…”

“…[1] On the other hand, a transition metal-catalyzed [2 + 2 + 2] cocyclization of alkynes is a useful and highly atom-economic way for the construction of various aromatic rings, [2] and this advantage compared to the abovementioned usual aryl-aryl coupling methodology prompted us to utilize the [2 + 2 + 2] cocyclization for the synthesis of biaryl derivatives. In this context, we have recently established a conceptually new method- [3] We speculated that this methodology could be further expanded to the construction of various arylnaphthalene skeletons VII if the [2 + 2 + 2] cocyclization of diyne VI and an aryne, in which C À C bond formation occurs three times, would proceed (Scheme 2). [4][5][6][7] Thus, the [2 + 2 + 2] cocyclization between VI and an aryne is expected to provide us with novel methodology for the synthesis of various arylnaphthalenes 1 in short-step reactions, and these arylnaphthalene derivatives should be key intermediates for the syntheses of chinensin, justicidin B, diphyllin, and taiwanins C and E ( Figure 1).…”