Iridium Complex-Catalyzed [2+2+2] Cycloaddition of α,ω-Diynes with Monoynes and Monoenes

Kezuka, Satoko; Tanaka, Shigeru; Ohe, Toshihito; Nakaya, Yoshihiko; Takeuchi, Ryo

doi:10.1021/jo051874c

Cited by 112 publications

(35 citation statements)

References 81 publications

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“…and catalyst to provide the corresponding benzene derivative in good yield. [8] In our catalytic system, slow addition of 1a (3 h) to the reaction mixture with 2b (2 equivs.) in the absence of AgOTf led only to self-dimerization and -trimerization of 1a (entry 12) while, in striking contrast, under the same reaction conditions, addition of AgOTf enabled the production of 3ab in 82 % yield (entry 13).…”

Section: Resultsmentioning

confidence: 99%

Efficient Activation of 2‐Iminomethylpyridine/Cobalt‐Based Alkyne [2+2+2] Cycloaddition Catalyst by Addition of a Silver Salt

2007

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The addition of silver triflate (AgOTf) or silver hexafluoroantimonate (AgSbF 6 ) significantly increased the activity of the 2-(arylimino)methylpyridine/cobalt(II) chloride hexahydrate (CoCl 2 ·6 H 2 O)/zinc catalyst in alkyne cyclotrimerizations thereby accelerating the reaction and enabling the use of unactivated, simple internal alkynes as the monoyne substrate: The rate of reaction was found to be highly dependent on the nature of the counter anion (X À ) and the ligand (L) in the postulated cationic cobalt(I) complex [LCo(I)] + X À .

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Section: Resultsmentioning

confidence: 99%

Efficient Activation of 2‐Iminomethylpyridine/Cobalt‐Based Alkyne [2+2+2] Cycloaddition Catalyst by Addition of a Silver Salt

2007

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“…[20] Upon screening several Ir complexes and ligands, [IrClA C H T U N G T R E N N U N G (cod)] 2 and 1,2-bis(diphenylphosphino)ethane (DPPE) mixture was found to be optimal at room temperature. Benzene was the solvent of choice compared to EtOH, THF, dioxane, acetone, and 1,2-dichloroethane.…”

Section: Synthesis Of Substituted Benzene Derivativesmentioning

confidence: 99%

[2+2+2] Cycloaddition Reactions Catalyzed by Transition Metal Complexes

2006

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Recent progress in the synthesis of benzene and 1,3-cyclohexadiene derivatives, and heterocyclic compounds such as pyridines, pyridones, pyrans, pyrimidine diones, etc, has been reviewed. The general mechanistic aspects of the [2 + 2 + 2] cycloaddition reaction are discussed. The asymmetric variants of these reactions are also discussed along with the proposed models of asymmetric induction. Keywords: arenes; catalysis; cycloaddition; heterocycles; metallacycles; transition metals IntroductionThe significance and increasing popularity of [2 + 2 + 2] cycloaddition reactions is evident from the number of reviews that have recently appeared in the literature. [1][2][3] The [2 + 2 + 2] cycloaddition reaction is remarkable in terms of its ability to utilize various unsaturated substrates such as alkynes, diynes, alkenes, imines, isocyanates, isothiocyanates, and CO 2 in the synthesis of a broad variety of highly substituted cyclic molecules such as benzenes, pyridines, pyridones, 1,3-cyclohexadienes, pyrones, thiopyridones and cyclohexanes. Multisubstituted benzenes and pyridines have traditionally been synthesized by aromatic electrophilic substitution (AES) reactions and a variety of metal-mediated coupling reactions. Although, these reactions are extremely efficient, they generally involve multistep syntheses. The application of AES reactions in the synthesis of polysubstituted aromatic rings is limited by the effect of the substituent groups and, hence, it may be very difficult or even impossible to add various functionalities at a specific position on the aromatic ring. On the other hand, [2 + 2 + 2] cycloaddition reactions are extremely atom-efficient and involve the formation of several C À C bonds in a single step. Another important feature of the [2 + 2 + 2] cycloaddition reaction is tolerance of a myriad of functional groups such as alcohols, amines, alkenes, ethers, esters, halogens, and nitriles. Moreover, the availability of numerous catalytic systems that have Adv. Synth. Catal. 2006, 348, 2307 -2327 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 2307 REVIEWS been efficient in tedious syntheses highlights the applicability of the [2 + 2 + 2] cycloaddition reaction. These are important requirements for the [2 + 2 + 2] cycloaddition reaction to become a universal synthetic tool for the synthesis of benzene, pyridine, and other cyclic derivatives. An important problem with the [2 + 2 + 2] cycloaddition reaction is the lack of chemoand regioselectivity observed in earlier reported reactions. However, significant effort has been focused on attaining a high degree of chemo-, regio-and even enantioselectivity with considerable success as evident from recent reports. Excellent reviews on [2 + 2 + 2] cycloaddition reactions are available. Kotha and co-workers have reviewed the synthesis of benzene derivatives by the cyclotrimerization of three alkyne functionalities utilizing transition metal systems as catalysts.[1] Their review is divided into: (a) intermolecular reactionsin which the three pi (alkyn...

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“…In an attempt to minimise the formation of dimer 11 , diyne 6a was added dropwise over 3 h to a stirring solution of monoyne 9a and catalyst 3 ,19 and this proved to be highly effective (entry 10). When using the 3-hour dropwise addition it was possible to reduce the number of equivalents of 1-hexyne 9a from four to two with no increase in homo-coupling (entry 11).…”

Section: Resultsmentioning

confidence: 99%

Highly Regioselective Synthesis of Substituted Isoindolinones via Ruthenium‐Catalyzed Alkyne Cyclotrimerizations

et al. 2013

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(Cyclooctadiene)(pentamethylcyclopentadiene)ruthenium chloride [Cp*RuCl(cod)] has been used to catalyze the regioselective cyclization of amide-tethered diynes with monosubstituted alkynes to give polysubstituted isoindolinones. Notably, the presence of a trimethylsilyl group on the diyne generally led to complete control over the regioselectivity of the alkyne cyclotrimerization. The cyclization reaction worked well in a sustainable non-chlorinated solvent and was tolerant of moisture. The optimized conditions were effective with a diverse range of alkynes and diynes. The 7-silylisoindolinone products could be halogenated, protodesilylated or ring opened to access a range of usefully functionalized products.

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Iridium Complex-Catalyzed [2+2+2] Cycloaddition of α,ω-Diynes with Monoynes and Monoenes

Cited by 112 publications

References 81 publications

Efficient Activation of 2‐Iminomethylpyridine/Cobalt‐Based Alkyne [2+2+2] Cycloaddition Catalyst by Addition of a Silver Salt

Efficient Activation of 2‐Iminomethylpyridine/Cobalt‐Based Alkyne [2+2+2] Cycloaddition Catalyst by Addition of a Silver Salt

[2+2+2] Cycloaddition Reactions Catalyzed by Transition Metal Complexes

Highly Regioselective Synthesis of Substituted Isoindolinones via Ruthenium‐Catalyzed Alkyne Cyclotrimerizations

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