Enantioselective Construction of Quaternary Carbon Centers by Catalytic [2 + 2 + 2] Cycloaddition of 1,6-Enynes and Alkynes

Shibata, Takanori; Arai, Yoshikazu; Tahara, Yu Ki

doi:10.1021/ol051876j

Cited by 75 publications

(24 citation statements)

References 21 publications

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“…Enynes 5 [71], 2a [72], 2b – e [46], 1a [73], 1b [74], 1c , d [75], 1e [73], and 6 [64] were prepared according to published procedures. 1 H, 13 C NMR and mass spectrometry data for compounds 3a , b [23], 3c , d [75], 3e [76] and 4a – e [46] were described elsewhere.…”

Section: Methodsmentioning

confidence: 99%

Asymmetric Au-catalyzed cycloisomerization of 1,6-enynes: An entry to bicyclo[4.1.0]heptene

Pradal¹,

Chao²,

Toullec³

et al. 2011

Beilstein J. Org. Chem.

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SummaryA comprehensive study on the asymmetric gold-catalyzed cycloisomerization reaction of heteroatom tethered 1,6-enynes is described. The cycloisomerization reactions were conducted in the presence of the chiral cationic Au(I) catalyst consisting of (R)-4-MeO-3,5-(t-Bu)2-MeOBIPHEP-(AuCl)2 complex and silver salts (AgOTf or AgNTf2) in toluene under mild conditions to afford functionalized bicyclo[4.1.0]heptene derivatives. The reaction conditions were found to be highly substrate-dependent, the best results being obtained in the case of oxygen-tethered enynes. The formation of bicyclic derivatives, including cyclopropyl pentasubstituted ones, was reported in moderate to good yields and in enantiomeric excesses up to 99%.

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Section: Methodsmentioning

confidence: 99%

Asymmetric Au-catalyzed cycloisomerization of 1,6-enynes: An entry to bicyclo[4.1.0]heptene

Pradal¹,

Chao²,

Toullec³

et al. 2011

Beilstein J. Org. Chem.

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“…[35] Recently, Shibata and coworkers have reported the use of chiral rhodium catalysts in the enantioselective [2 + 2 + 2] cycloaddition reaction of 1,6-enynes and alkynes to afford substituted bicyclic 1,3-cyclohexadienes containing quaternary carbon stereocenters. [36] Terminal and internal alkynes could be utilized in this reaction. The use of symmetrical monoynes resulted in higher ees compared to unsymmetrical monoynes (Scheme 21).…”

Section: Synthesis Of Substituted 13-cyclohexadiene 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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“…(244)) [1307]. Enantioselective rhodium-catalyzed [2 + 2 + 2]cycloaddition of 1,6-enynes with alkynes was described [1308]. (244) Nickel catalyzed an asymmetric cycloaddition of nitrones with activated cyclopropanes (Eq.…”

Section: Cycloadditionsmentioning

confidence: 99%

Transition metals in organic synthesis: Highlights for the year 2005

Söderberg

2008

Coordination Chemistry Reviews

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Enantioselective Construction of Quaternary Carbon Centers by Catalytic [2 + 2 + 2] Cycloaddition of 1,6-Enynes and Alkynes

Cited by 75 publications

References 21 publications

Asymmetric Au-catalyzed cycloisomerization of 1,6-enynes: An entry to bicyclo[4.1.0]heptene

Asymmetric Au-catalyzed cycloisomerization of 1,6-enynes: An entry to bicyclo[4.1.0]heptene

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

Transition metals in organic synthesis: Highlights for the year 2005

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