The More Gold—The More Enantioselective: Cyclohydroaminations of γ‐Allenyl Sulfonamides with Mono‐, Bis‐, and Trisphospholane Gold(I) Catalysts

Rodríguez, L.; Roth, Torsten; Lloret‐Fillol, Julio; Wadepohl, Hubert; Gade, Lutz H.

doi:10.1002/chem.201103140

Cited by 62 publications

(49 citation statements)

References 93 publications

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“…A mechanistic study of this system suggested that the catalyst contained an aurophilic Au-Au interaction, in addition to a strong interaction between the sulfonamide and gold, crucial for enantioselectivity [59]. To corroborate these observations, Gade et al showed that in an alternative catalyst system capable of incorporating up to three gold atoms, higher selectivities were exclusively observed as the number of gold centers increased to three, suggesting aurophilic interactions are at play [60]. Gade also utilized enantiopure ditopic cyclophosphazane ligands to accomplish this transformation with good to modest ees [61].…”

Section: Intramolecular Cyclizationsmentioning

confidence: 83%

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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Section: Intramolecular Cyclizationsmentioning

confidence: 83%

Enantioselective Gold-Catalyzed Synthesis of Heterocyclic Compounds

Miles

Toste

2015

Topics in Heterocyclic Chemistry

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“…The pendant arm of 129 was coordinated to various gold salts, accessing hetero bimetallic systems similar to those previously reported [49]. Moreover, two trimetallic gold complexes of ligands 126 and 127 were synthesized, where each phosphine was coordinated to a separate AuCl unit (Scheme 21) [51]. Both inter-and intra-molecular aurophilic interactions were found for [Au 3 Cl 3 (μ 3 -κ 1 ,κ 1 ,κ 1 -NP 3 The steric bulk of ligands 118, 119 and 127 appeared to prohibit tridentate coordination, which is useful for enhancing overall stability and potentially retarding decomposition during catalytic applications.…”

Section: Nitrogen (N(ch 2 Pr 2 ) 3 )mentioning

confidence: 97%

“…For eachallenyl sulfonamide substrate studied, moving from mono-to bi-to tri-dentate phospholane ligands (with one, two and three coordinated AuCl units, respectively) gave greater catalytic activity and enantioselectivity. Aurophilic interactions may be responsible for this behavior (Section 2.4) [51]. As Ru-C bonds in cyclometalated complexes are easily cleaved, the biscyclometalated ruthenium complex [Ru(κ 3 P,κ 2 C-NP 3 DPP )] (135) was investigated for reactivity with both H 2 and Ph 2 SiH 2 [52].…”

Section: Nitrogenmentioning

confidence: 99%

“…Two such ligands were reported with either 2,5-dimethyl (NP 3 DMP , 126) or 2,5-diphenyl (NP 3 DPP , 127) substituents on the phospholane ring (Figure 2) [50][51][52]. Complexation of these ligands to the rhodium(I) precursor [Rh(cod) 2 ]BF 4 showed different coordination modes, with the less bulky 126 coordinating through all three phosphine groups to afford [Rh(cod)(κ 3 -NP 3 DMP )] (128), while the sterically cumbersome 127 only through two: [Rh(cod)(κ 2 -NP 3 DPP )] (129, Scheme 21).…”

Section: Nitrogen (N(ch 2 Pr 2 ) 3 )mentioning

confidence: 99%

“…M a n u s c r i p t The activation of allene groups towards nucleophilic attack is becoming a powerful organic transformation in natural-product synthesis and pharmaceutrical chemistry [73]. The use of the trinuclear C 3 -symmetric gold(I) complex [Au 3 Cl 3 (μ 3 -κ 1 ,κ 1 ,κ 1 -NP 3 DPP )] (131) was reported for the asymmetric intramolecular cyclohydroamination of N-protected -allenyl sulfonamides, in conjunction with silver(I) salts as hydride abstraction agents (Scheme 33) [51]. When silver salts with rigorously noncoordinating anions were studied for this reaction, racemic mixtures were obtained, but moving to the slightly more coordinating benzoate anion (OBz), resulted in high conversions with high enantioselectivities (up to 95% ee).…”

Section: Nitrogenmentioning

confidence: 99%

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Beyond Triphos – New hinges for a classical chelating ligand

Phanopoulos

Miller

Long

2015

Coordination Chemistry Reviews

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Branched triphosphine ligands have been less widely studied than mono-and bidentate analogues. The most studied ligand of this type is Triphos Ph (CH 3 C(CH 2 PPh 2 ) 3 ). Substitution of the apical C-CH 3 moiety with boron, silicon, tin, nitrogen or phosphorus fragments has generated a new family of ligands, in some cases displaying varying coordination chemistry and reactivity to the parent carbonbased system. This review includes the synthetic strategies implemented to afford these ligands, as well as derivatives by way of varying the phosphine substituents. Although not exhaustive, relevant types of reported complexes featuring these ligands are discussed, as well as their reactivity and catalytic applications. Through critical analysis, common themes and chemical trends across this family of apical heteroatomic, branched triphosphines can be identified, leading to improvements in current chemical applications, as well as new areas that remain underdeveloped.

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Hydroamination of Alkenes

Reznichenko

Hultzsch

2015

Organic Reactions

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The addition of an amine NH‐functionality to alkenes (including vinyl arenes, conjugated dienes, allenes or ring‐strained alkenes), the so‐called hydroamination, represents a simple and highly atom‐economical approach for the synthesis of nitrogen‐containing products. A large variety of catalyst systems are available, ranging from alkali, alkaline earth, rare earth, Group 4 and Group 5 metals, to late transition metal catalysts, and, less prominent, Brønsted and Lewis acid‐based catalyst systems. The mode of operation of these catalyst systems can vary significantly and the different reaction mechanisms and the scope and limitations are discussed. While intramolecular hydroamination reactions can be readily achieved with a large number of catalyst systems, significantly fewer examples for the more challenging intermolecular hydroamination are known, especially for unactivated alkenes. The stereoselective hydroamination has also received significant attention due to the importance of chiral nitrogen‐containing molecules in pharmaceutical industry. A variety of highly selective chiral catalyst systems have been developed for intramolecular hydroaminations, while examples of intermolecular asymmetric hydroaminations are scarce. Hydroamination in the context of this review article is defined as the addition of HNR 2 across a non‐activated, unsaturated carbon‐carbon multiple bond. This review focuses on the hydroamination reaction of simple, non‐activated alkenes. The addition of amines to slightly activated alkenes, such as vinyl arenes, 1,3‐dienes, strained alkenes (norbornene derivatives, methylenecyclopropenes) and allenes is closely related and is covered as well. However, hydroamination reactions of alkynes and Aza‐Michael reactions involving the addition of an N‐H fragment across the conjugated or otherwise activated double bond of a Michael acceptor are not covered. The scope of amine types includes ammonia, primary and secondary aliphatic and aromatic amines, azoles, and hydrazines. N ‐Protected amines, such as ureas, carboxamides, and sulfonamides are covered as well, as they are important substrates for metal‐free and late transition metal‐based catalysts. The literature through January 2011 will be covered with two selected references from 2012 (comprising Table 3D). A supplemental reference list is provided for reports appearing February 2011 through April 2015. The chapter is organized by the nature of the carbon unsaturation to which the amine is added. Ranging from less reactive substrates such as ethylene and unactivated alkenes, to slightly activated substrates, such as vinyl arenes, and more activated substrates, including conjugated dienes, allenes and strained alkenes. Enantioselective hydroamination reactions, an area that has seen significant progress over the past decade, are discussed next. Finally, tandem hydroamination/carbocyclization reactions of aminodialkenes provide rapid access to complex alkaloidal skeletons. The tables at the end of the chapter are separated into five main sections: achiral intermolecular hydroamination, achiral intramolecular hydroamination, enantioselective intermolecular hydroamination, enantioselective intramolecular hydroamination, and tandem hydroamination/carbocyclization. Within the first four sections the tables are further divided into subsections based on the participating alkene, i.e. alkenes, vinyl arenes, dienes, allenes, and strained alkenes.

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The More Gold—The More Enantioselective: Cyclohydroaminations of γ‐Allenyl Sulfonamides with Mono‐, Bis‐, and Trisphospholane Gold(I) Catalysts

Cited by 62 publications

References 93 publications

Enantioselective Gold-Catalyzed Synthesis of Heterocyclic Compounds

Enantioselective Gold-Catalyzed Synthesis of Heterocyclic Compounds

Beyond Triphos – New hinges for a classical chelating ligand

Hydroamination of Alkenes

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