Synthesis of New Phosphahelicene Scaffolds and Development of Gold(I)‐Catalyzed Enantioselective Allenene Cyclizations

Aillard, Paul; Retailleau, Pascal; Voituriez, Arnaud; Marinetti, Angéla

doi:10.1002/chem.201501697

Cited by 51 publications

(33 citation statements)

References 54 publications

(33 reference statements)

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“…The phosphahelicene oxides 2 have been prepared as described previously, by Ni(cod) 2 /PPh 3 promoted cyclotrimerization of triyne ( R P )‐ 1 (Scheme ) . After chromatographic separation of the isomeric oxides ( R P ,P )‐ 2a and ( R P ,M )‐ 2b (silica gel, petroleum ether/EtOAc gradient from 15% to 40%), needle‐like crystals of ( R P ,P )‐ 2a suitable for X‐ray diffraction studies were grown from a CHCl 3 solution.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and X‐ray diffraction study of a chiral bis‐phosphahelicene palladium (II) complex

et al. 2019

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As a complement to our previous studies on the development of a class of chiral phosphahelicenes, this article discloses the synthesis, spectroscopic, and structural characterizations of a new phosphahelicene transition metal complex. It demonstrates the ability of these hindered chiral ligands to coordinate Pd (II) in trans‐complexes Cl2Pd(L*)2. In the solid state, the complex adopts a C2‐symmetric arrangement with two ligands facing each other on the same face of the coordination plane. X‐Ray data highlight bending of the Pd (II) unit from the expected planar coordination geometry that might be due to a significant π‐π stacking effect between the central rings of two helical units.

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Section: Methodsmentioning

confidence: 99%

Synthesis and X‐ray diffraction study of a chiral bis‐phosphahelicene palladium (II) complex

et al. 2019

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“…In 2015, Marinetti, Voituriez and co‐workers reported a series of phosphahelicene auric ligands . The enantiopure phospha[6]helicene‐derived gold complex [HelPhos‐ P ‐AuCl] ( Au4 , Scheme ), which was readily accessed through a [2+2+2] intramolecular alkyne cyclotrimerization reaction, proved highly effective in intramolecular [2+2] cycloadditions of 1,6‐allene‐enes.…”

Section: Cycloaddition Reactionsmentioning

confidence: 99%

“…The acyclic TADDOL‐based phosphoramidite–gold complex [{( S , S , S ,S)‐ L5 }AuCl] developed by Fürstner and co‐workers was very effective in the [4+2] cycloadditions of both N ‐tosyl‐tethered and malonate‐tethered allene‐dienes (Scheme , conditions A ) . Complementarily, the chiral gold catalyst [HelPhos‐ P ‐AuCl] ( Au4 ) developed by Voituriez, Marinetti, and co‐workers was especially effective for the intramolecular [4+2] cyclization of gem ‐disulfone‐functionalized allene‐dienes to afford trans ‐hexahydroindene 122 k in 83 % yield and 84 % ee (Scheme , conditions B ) . This kind of bicyclic compound 122 k had heretofore never been obtained through gold‐catalyzed enantioselective transformations.…”

Section: Cycloaddition Reactionsmentioning

confidence: 99%

“…The gold(I)‐catalyzed annulation of allene‐enes in the presence of nucleophiles provided trans ‐3,4‐disubstituted pyrrolidines or cyclopentane derivatives in sharp contrast with the cis ‐fused bicyclic products obtained in the [2+2]cycloadditions. The groups of Toste and Marinetti accomplished the enantioselective nucleophilic addition/cyclization reaction of allene‐enes in 2011 and 2015, respectively (Scheme ).…”

Section: Cyclization Of C−c Multiple Bonds With Tethered Nucleophilesmentioning

confidence: 99%

“…The chiral gold catalyst endo ‐(P)‐ Au4 (see above), newly developed by Marinetti, Voituriez, and co‐workers, was also applied in the tandem cyclization/addition of gem ‐sulfone‐functionalized allene‐enes 201 a – c in the presence of external nucleophiles . These reactions afforded the desired cyclopentane derivatives 202 with three contiguous stereogenic centers with totally anti diastereoselectivity and high enantioselectivity (82–90 % ee ) irrespective of what kind of alcohol was used (EtOH, branched secondary alcohols, or allylic alcohol).…”

Section: Cyclization Of C−c Multiple Bonds With Tethered Nucleophilesmentioning

confidence: 99%

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Gold‐Catalyzed Enantioselective Annulations

Zhang

2016

Chemistry A European J

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Non-oxidative,regioselective,and convergent access to densely functionalized oxazoles is realized in af unctional-group tolerant manner using alkynyl thioethers.S ulfur-terminated alkynes provideaccess to reactivity previously requiring strong donor-substituted alkynes such as ynamides.Sulfur does not act in an analogous donor fashion in this gold-catalyzed reaction, thus leading to complementary regioselective outcomes and addressing the limitations of using ynamides. Compared to other heteroatom-substituted alkynes,alkynyl thioethers are remarkably little explored in intermolecular late-transition-metal catalysis,d espite being readily accessed and robust. [1, 2] Ynamides,i nc ontrast, are privileged sub-strates:i np-acid catalysis their donor nature aids metal-alkyne coordination and affords highly polarized electro-philes,t hus providing the high chemo-and regioselectivity required for the discovery of efficient intermolecular reactions (Scheme 1a). [3,4] As the resulting inclusion of ad onor-nitrogen atom limits the utility of the products,r etaining the reactivity profile of these transformations whilst accessing more flexible and readily elaborated substitution patterns would be desirable.T he value of sulfur-substituted compounds [5] coupled with progress in C À Ca nd C-heteroatom bond formation from CÀSbonds, [6] renders alkynyl thioethers appealing alternatives to ynamides.I ndeed the ketenethio-nium pathway (Scheme 1a)f rom alkynyl thioethers has recently been invoked in proton-catalyzed reactions with nitriles [2g,h] and gold-catalyzed reactions with sulfides. [2i] Ynamides enabled the discovery of formal [3+ +2] dipolar cycloadditions with nucleophilic nitrenoids, [7] thus allowing intermolecular access to a-imino gold carbene-type reactivity for heterocycle synthesis (Scheme 1b). [8, 9] Such reactions, which do not depend on ynamides,a re scarce. [8b,h] As trong donor alkyne substituent proved critical in the formation of oxazoles using N-acyl pyridinium N-aminides,aselectron-rich alkynes such as anisole derivatives did not react (Scheme 1b, inset). [8a,b] Oxazoles are valuable synthetic intermediates [10,11] and structural components in bioactive natural products, [12] agrochemicals, [13] ligands, [14] and functional materials. [15] Despite recent advances,asingle modular and convergent route to trisubstituted oxazoles,which provides the structural and functional-group diversity needed across the 2-, 4-, and 5-positions,r emains unrealized. [16] Following our interest in the use of gold catalysis with sulfides [17] we report here on the reactivity of alkynyl thioethers with nucleophilic nitrenoids to prepare oxazoles. Importantly,t he regioselectivity is not consistent with ac on-trolling ketenethionium species.T he sulfur group plays an alternative role in enabling reactivity,t hus proving complementary to donor-enabled approaches. Ther eaction of the alkynyl thioether 1a and aminide 2a (Table 1) showed that conversion into the oxazole 3 was possible at 125 8 8Ci n1 ,2-dichlorobenzene (1,2-DCB;s ...

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Addition Reactions: Cycloaddition

Dennis¹

2019

Organic Reaction Mechanisms Series

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Synthesis of New Phosphahelicene Scaffolds and Development of Gold(I)‐Catalyzed Enantioselective Allenene Cyclizations

Cited by 51 publications

References 54 publications

Synthesis and X‐ray diffraction study of a chiral bis‐phosphahelicene palladium (II) complex

Synthesis and X‐ray diffraction study of a chiral bis‐phosphahelicene palladium (II) complex

Gold‐Catalyzed Enantioselective Annulations

Addition Reactions: Cycloaddition

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