Dirhodium(II) Tetra(<i>N</i>-(dodecylbenzenesulfonyl)prolinate) Catalyzed Enantioselective Cyclopropenation of Alkynes

Davies, Huw M. L.; Lee, Gene H.

doi:10.1021/ol049928c

Cited by 117 publications

(55 citation statements)

References 29 publications

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“…[7][8][9] Although high levels of enantioselectivity (up to 99 % ee) in cyclopropenations of terminal alkynes with aryldiazoacetates [7a] or arylvinyldiazoacetates [7b] under catalysis by [Rh 2 (S-dosp) 4 ] (4) have been reported by Davies and co-workers, the goal for the reaction with a-alkyl-a-diazoesters remains elusive because of the propensity to form a,b-unsaturated esters through a 1,2-hydride shift.…”

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confidence: 99%

Highly Enantioselective Cyclopropenation Reaction of 1‐Alkynes with α‐Alkyl‐α‐Diazoesters Catalyzed by Dirhodium(II) Carboxylates

Goto¹,

et al. 2011

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As a result of enormous ring strain, cyclopropene compounds display a range of diverse reactivities in both noncatalytic and transition-metal-catalyzed transformations, thus presenting unique opportunities for organic synthesis. [1,2] To further enhance the synthetic potential of cyclopropenes, the development of expeditious methods for the synthesis of enantioenriched cyclopropenes is highly desirable.[3] In this context, a cyclopropenation reaction of alkynes with diazo compounds that is catalyzed by chiral dirhodium(II) complexes represents one of the most powerful means for the construction of this class of optically active building blocks. Doyle, Müller, and co-workers were the first to demonstrate asymmetric induction (up to ! 98 % ee) in cyclopropenation reactions of terminal alkynes including propargyl alcohol or propargylamine derivatives with diazoacetates using [Rh 2 (5S-mepy) 4 ] (2 a; Scheme 1) as a chiral catalyst.[4] Doyle et al. also reported an enantioselective intramolecular cyclopropenation of diazoacetates, in which [Rh 2 (4S-ibaz) 4 ] (2 b) provided macrocyclic cyclopropenes in up to ! 99 % ee.[5] Corey and coworkers demonstrated that a new mixed carboxylate/carboxamidate catalyst [Rh 2 (OAc)(dpti) 3 ] (3) is highly exceptional for cyclopropenation of a broad range of terminal alkynes with ethyl diazoacetate.[6] The extension of this methodology to include a-substituted a-diazoacetates is particularly attractive because it has the capability to form cyclopropenes with a quaternary stereogenic carbon center. [7][8][9] Although high levels of enantioselectivity (up to 99 % ee) in cyclopropenations of terminal alkynes with aryldiazoacetates [7a] or arylvinyldiazoacetates [7b] under catalysis by [Rh 2 (S-dosp) 4 ] (4) have been reported by Davies and co-workers, the goal for the reaction with a-alkyl-a-diazoesters remains elusive because of the propensity to form a,b-unsaturated esters through a 1,2-hydride shift.[10] Panne and Fox recently disclosed that dirhodium(II) tetrapivalate exhibits high selectivity for cyclopropenation over alkene formation in the reaction of terminal alkynes with a-alkyl-a-diazoesters. [11,12] However, to the best of our knowledge, an enantioselective version of this reaction has not been reported.Our research group has previously demonstrated the first examples of highly enantio-, diastereo-, and chemoselective intramolecular C À H insertion reactions of a-alkyl-a-diazoesters by using dirhodium(II) tetrakis[N-phthaloyl-(S)-tertleucinate] ([Rh 2 (S-pttl) 4 ], 1 a) in which high levels of asymmetric induction (up to 95 % ee) were achieved. [13][14][15] Herein, we report that [Rh 2 (S-tbpttl) 4 ] (1 f), a new dirhodium(II) carboxylate complex that incorporates N-tetrabromophthaloyl-(S)-tert-leucinate as chiral bridging ligands, catalyzes the cyclopropenation reaction of terminal alkynes with 2,4-dimethyl-3-pentyl a-alkyl-a-diazoacetates to give 1,2-disubstituted 2-cyclopropenecarboxylates in good to high yields and with up to 99 % ee. Scheme 1. Chiral dirhodium(II) com...

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confidence: 99%

Highly Enantioselective Cyclopropenation Reaction of 1‐Alkynes with α‐Alkyl‐α‐Diazoesters Catalyzed by Dirhodium(II) Carboxylates

Goto¹,

et al. 2011

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“…While complexes with α,α,α,α-and α,α,α,β-conformations, which have non-equivalent catalyst faces, are likely to induce low or no enantioinduction as their more accessible and kinetically active face is achiral. This previous proposal from Davies et al originates from their discovery of Rh2(S-DOSP)4 catalyst (Scheme 2) [36], which offered extraordinary enantioselectivity in a wide range of chemical transformations (up to 99% ee) [7,13,36,40,42,44,47,48,[55][56][57][58][59][60][61][62][63][64][65][66][67][68]. This exceptional enantioselectivity of Rh2(S-DOSP)4 was proposed to originate from a favored α,β,α,β-arrangement of ligands adapted during catalysis.…”

Section: Ligand Blocking Groups Arrangementsmentioning

confidence: 99%

On the Structure of Chiral Dirhodium(II) Carboxylate Catalysts: Stereoselectivity Relevance and Insights

Adly

2017

Catalysts

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Abstract:Modern experiments have offered alternative interpretations on the symmetry of chiral dirhodium(II) carboxylate complexes and its relationship to their level of enantioselectivity. So, this contribution is to provide an insight on how the knowledge around the structure of these catalysts has evolved with a particular emphasis on the impact of this knowledge on enantioselectivity prediction and catalyst design.

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“…When the reaction was carried out at 40 °C, the desired product 3a could be obtained in 66% yield (entry 8). After screening BF 3 ·Et 2 O, it was found that acetone, CH 3 CN, DMF, and iodine did not give superior results in terms of either reactivity or stereoselectivity (entries [9][10][11][12].…”

Section: Paper Syn Openmentioning

confidence: 99%

“…8 Corey and co-workers also reported a significantly improved enantioselective cyclopropenation of ethyl diazoacetate with 1-alkynes using a new rhodium complex, Rh 2 (OAc)(DPTI) 3 , as a catalyst. 9 Although high levels of enantioselectivity (up to 99% ee) in cyclopropenations of terminal alkynes with aryldiazoacetates under catalysis by [Rh 2 (S-dosp) 4 ] have been reported by Davies and coworkers, 10 stereoselective syntheses of the corresponding cyclopropenylphosphonates using such a strategy remain scarce. 11 α-Diazophosphonates are phosphorus analogues of α-diazoacetates, and therefore could undergo a range of chemical transformations and the synthesis of varieties of functionalized phosphorous compounds.…”

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Diastereoselective [Cu(MeCN)4BF4/BF3·Et2O]-Catalyzed Cyclopropenation of Alkynes: Asymmetric Synthesis of β-Amino-α-cyclopropenyl Phosphonates

Ge¹,

Liu²,

Cheng³

et al. 2017

SynOpen

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The diastereospecific formation of β-amino-α-cyclopropenyl phosphonates has been achieved in moderate yields from the cyclopropenation of 1-alkynes with dialkyl α-diazophosphonates. The reaction was performed by using a combined catalyst consisting of Cu(MeCN)4BF4 and BF3·Et2O as additive in dichloromethane at 40 °C. A possible mechanism for the reaction has been proposed to explain the origin of the activation and the asymmetric induction. This method provides a versatile approach to β-amino-α-cyclopropenylphosphonates containing a quaternary stereogenic center with good efficiency and diastereoselectivity.

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Dirhodium(II) Tetra(N-(dodecylbenzenesulfonyl)prolinate) Catalyzed Enantioselective Cyclopropenation of Alkynes

Abstract: Dirhodium tetrakis((S)-N-(dodecylbenzenesulfonyl)prolinate) (Rh(2)(S-DOSP)(4)) is an effective chiral catalyst for the enantioselective cyclopropenation of alkynes by methyl aryldiazoacetates. [reaction: see text]

Cited by 117 publications

References 29 publications

Highly Enantioselective Cyclopropenation Reaction of 1‐Alkynes with α‐Alkyl‐α‐Diazoesters Catalyzed by Dirhodium(II) Carboxylates

Highly Enantioselective Cyclopropenation Reaction of 1‐Alkynes with α‐Alkyl‐α‐Diazoesters Catalyzed by Dirhodium(II) Carboxylates

On the Structure of Chiral Dirhodium(II) Carboxylate Catalysts: Stereoselectivity Relevance and Insights

Diastereoselective [Cu(MeCN)4BF4/BF3·Et2O]-Catalyzed Cyclopropenation of Alkynes: Asymmetric Synthesis of β-Amino-α-cyclopropenyl Phosphonates

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