Asymmetric Au(i)-catalyzed synthesis of bicyclo[4.1.0]heptene derivatives via a cycloisomerization process of 1,6-enynes

Chao, Chung-Meng; Beltrami, Denis; Toullec, Patrick Y.; Michelet, Véronique

doi:10.1039/b913554e

Cited by 128 publications

(48 citation statements)

References 61 publications

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“…Based on our ongoing program on asymmetric gold catalysis [46,49–52], and on literature reports [53–55], we selected 4-MeO-3,5-( t -Bu) 2 -MeOBIPHEP-(AuCl) 2 complex [56–58] as the best candidate for such a transformation. Initial experiments were performed using N -tosyl allyl substrate 1a and oxygen-linked propargylic 1,6-enyne 2a as model substrates (Table 1).…”

Section: Resultsmentioning

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: Resultsmentioning

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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“…[3] This is the case also for the cycloisomerizations of 1,6-enynes into bicycloA C H T U N G T R E N N U N G [4.1.0]heptenes which are specifically targeted in this paper. Enantioselective variants make use of Ir/TolBinap, [5a] Au/MeO-BIPHEP [8] and Rh/chiral diene [9] complexes as the chiral catalysts. Enantioselective variants make use of Ir/TolBinap, [5a] Au/MeO-BIPHEP [8] and Rh/chiral diene [9] complexes as the chiral catalysts.…”

Section: Introductionmentioning

confidence: 99%

“…[5a] More recently, chiral gold-diphosphine [8] and rhodium-diene [9] complexes have been applied succesfully to these cycloisomerizations, on a rather restricted range of substrates (1 example, 98% ee and 7 examples, 68-95% ee, respectively). Moreover, only a very few examples have been reported so far of analogous cycloisomerizations of N-tethered enynes by using other transition metal catalyts.…”

Section: Introductionmentioning

confidence: 99%

Cyclometalated N‐Heterocyclic Carbene‐Platinum Catalysts for the Enantioselective Cycloisomerization of Nitrogen‐Tethered 1,6‐Enynes

et al. 2011

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Platinum(II) complexes which combine six-membered N-heterocyclic carbene-containing metallacyclic units and monodentate chiral phosphines have been prepared. The key step of their synthesis is the intramolecular oxidative addition of N-2-iodobenzylimidazolylidene-platinum (0) ]heptenes has been established by X-ray diffraction studies. The method has been extended then to the cycloisomerization of dienynes with enantiotopic vinyl groups. An (S)-phenyl-Binepine-platinum(II) complex allows total diastereoselectivity and high enantioselectivity levels to be attained in these reactions (ees up to 95%) which represent the first enantioselective desymetrizations achieved via enyne cycloisomerizations.

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“…The use of an electrophilic allene and chiral phosphoramidite catalyst afforded various pyrroloindoline derivatives (Scheme 22). In the field of enyne cyclization, Michelet and coworkers reported in 2009 the enantioselective synthesis of functionalized cyclopropanated dihydrofurans and tetrahydropyridines utilizing a chiral biaryl bisphosphine gold catalyst (Scheme 23) [97]. Although yields were generally modest, excellent enantioselectivities were obtained in all cases.…”

Section: Intramolecular Cyclizationsmentioning

confidence: 98%

Enantioselective Gold-Catalyzed Synthesis of Heterocyclic Compounds

Miles

Toste

2015

Topics in Heterocyclic Chemistry

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Asymmetric gold-catalyzed syntheses of a diverse range of heterocycles are described herein. This chapter outlines efforts toward the construction of these molecules via intermolecular, intramolecular, and tandem cyclization strategies. Additionally, asymmetric hydrogenation and epoxidation approaches are detailed. These methodologies generally utilize substrates containing soft, unsaturated carbon-carbon bonds, which can easily interact with the carbophilic gold atom(s). Mostly through the use of bis-or monophosphine ligands, modest to excellent yields and enantioselectivities are obtained for a variety of partially and fully saturated heterocycles. Although steric variation of the phosphine catalyst is the most commonly used strategy for enantioinduction, the use of chiral counteranions has proven useful for more challenging transformations. This chapter includes only examples of syntheses where a chiral gold catalyst is used in the direct formation of the heterocycle; examples of pendant functionalization of an existing heterocycle or chirality transfer from enantioenriched substrate to product are not included.

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Asymmetric Au(i)-catalyzed synthesis of bicyclo[4.1.0]heptene derivatives via a cycloisomerization process of 1,6-enynes

Cited by 128 publications

References 61 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

Cyclometalated N‐Heterocyclic Carbene‐Platinum Catalysts for the Enantioselective Cycloisomerization of Nitrogen‐Tethered 1,6‐Enynes

Enantioselective Gold-Catalyzed Synthesis of Heterocyclic Compounds

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