Highly enantioselective construction of tertiary thioethers and alcohols via phosphine-catalyzed asymmetric γ-addition reactions of 5H-thiazol-4-ones and 5H-oxazol-4-ones: scope and mechanistic understandings

Wang, Tianli; Yu, Zhaoyuan; Hoon, Ding Long; Huang, Kuo‐Wei; Lan, Yu; Lü, Yixin

doi:10.1039/c5sc01614b

Cited by 118 publications

(47 citation statements)

References 139 publications

(32 reference statements)

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“…In contrast, Lan, Lu, and co-workers found an intermolecular hydrogen bond to be responsible for good levels of asymmetric induction in the g-addition of 5H-thiazol/oxazol-4-onest o allenoates (Scheme 2D). [11] Our computations show that the lowest-energy transition state features an intermolecular hydrogen bond (1.92 , (S)-TS;F igure 4, top) between the carbamate and the substrate and is thus similar to the models proposed by Jacobsen and Lu (Scheme 2). Further stabilization comes from hydrogen-bonding interactions between two of the acidic hydrogen substituents a and b to the phosphonium ion (2.20 and 2.34 , respectively).…”

supporting

confidence: 54%

Importance of Intermolecular Hydrogen Bonding for the Stereochemical Control of Allene–Enone (3+2) Annulations Catalyzed by a Bifunctional, Amino Acid Derived Phosphine Catalyst

2016

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The origin of stereoselectivity in the (3+ +2) annulation of allenes and enones catalyzedbyanamino acid derived phosphine catalyst has been investigated by the use of dispersion-corrected density functional theory.Anintermolecular hydrogen bond between the intermediate zwitterion and the enone was found to be the key interaction in the two enantiomeric transition states.A dditional stabilization is provided by intermolecular hydrogen-bonding interactions between acidic positions on the catalyst backbone and the substrate.Enantioselectivity occurs because the intermolecular hydrogen bond in the transition state leading to the minor enantiomer is only possible at the expense of reactant distortion.Phosphines are powerful nucleophilic organocatalysts that continue to find application in the rapid construction of densely functionalized cyclic and acyclic biologically important molecules.[1] Their significance is beautifully exemplified by (3+ +2) annulation reactions of allenes and activated olefins or imines under the catalysis of PR 3 derivatives.[2] Since the initial report of this transformation in 1995, [2a] asymmetric variants of this reaction have been developed relatively slowly despite their potential in natural product total synthesis.[3] The seminal example of an enantioselective (3+ +2) annulation with an amino acid derived phosphine catalyst was reported by Cowen and Miller in 2007 (Scheme 1, top). [4] This reaction unifies simple allenoate esters and enones under the catalysis of an amino acid derived b-aminophosphine with good to excellent selectivity.S ince then, several other organophosphine catalysts derived from amino acids have been reported for this and related reactions. [5,6] All these catalysts feature ah ydrogen-bonding group (amide or thiourea) vicinal to ad iphenylphosphine group.T od elineate the interactions responsible for enantioselectivity in this important class of transformations,w es tudied the initial reaction reported by Cowen and Miller. Therole of the functional groups and the origin of stereoselectivity in this transformation were established by computational investigation of the bond-forming steps of the reaction mechanism. Elucidation of the key stabilizing interactions in the enantiodetermining transition state will assist the development of novel organocatalysts for related transformations and assist the formulation of induction models.Them echanism (Scheme 1, bottom) and the origins of regioselectivity of the corresponding achiral reaction with PMe 3 have been studied previously. [7] These studies have demonstrated that the catalyst initially undergoes addition to the b-position of the allenoate to give az witterionic species. Theb ackbone geometry of this intermediate is rigidified by aclose contact between the negatively charged oxygen atom and the phosphonium ion. To ensure that the same interaction controls the geometry of the reactive intermediate when abulkier phosphine catalyst is used, we studied the zwitterion resulting from the addition of PPh 3 (Figu...

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supporting

confidence: 54%

Importance of Intermolecular Hydrogen Bonding for the Stereochemical Control of Allene–Enone (3+2) Annulations Catalyzed by a Bifunctional, Amino Acid Derived Phosphine Catalyst

2016

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“…s, 2 H), 1.20 (br. 13 C NMR (100.6 MHz, CDCl 3 ): δ 199. 13 C NMR (100.6 MHz,CDCl 3 ): δ 198.6,181.4,163.3,155.1,153.4,135.7,135.5,135.4,135.0,134.7,134.4,131.5,129.0,128.9,128.3,128.0,127.9,77.2,69.3,67.9,64.0,13.5.…”

Section: Methodsmentioning

confidence: 99%

“…19-1.50 (m, 21 H). 13 C NMR (100.6 MHz, CDCl 3 ): δ 197. 2, 182.0, 163.2, 154.5, 153.9, 135.6, 135.3, 131.6, 128.8, 83.7, 82.1, 77.2, 63.7, 27.7, 13.7 198.6, 181.3, 164.0, 155.3, 153.6, 135.7, 131.6, 129.0, 128.9, 77.2, 64.0, 62.5, 54.4, 14.1, 14.0.…”

Section: Methodsmentioning

confidence: 99%

“…As a nitrogen-sulfur-containing heterocycle, thiazol-4-one has played an important role as a widely exploited pharmacophore in medicinal chemistry having varied biological activity, such as anticancer, [4] antifungal, [5] antimicrobial, [6] anti-inflammatory, [7] antimelanogenic [8] as well as antioxidant activity. These including Brønsted base catalyzed asymmetric Michael addition of thiazol-4-ones to different Michael acceptors, such as α'silyloxy enones, [10] nitroolefins, [11] and maleimides or 1,4-naphthoquinones, [12] phosphine-catalyzed enantioselective γ-additions of thiazol-4-ones to allenoates, [13] as well as Ir-catalyzed asymmetric allylation of substituted thiazol-4-ones. However, only a few examples have been documented for catalytic asymmetric transformations that yield chiral thiazol-4-ones at C-5.…”

Section: Introductionmentioning

confidence: 99%

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Organocatalytic Enantioselective α‐Amination of Thiazol‐4‐one‐5‐carboxylates with Azodicarboxylates

Wang

Fan

2018

Asian J Org Chem

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An effective method for the asymmetric synthesis of 5-hydrazinothiazol-4-one-5-carboxylates was developed. The tetrasubstituted chiral carbon center was generated by asymmetric amination of thiazol-4-one-5-carboxylate with azodicarboxylate catalyzed by a bifunctional squaramidebased (1R,2R)-cyclohexane-1,2-diamine backbone in good to excellent yields (40-96%) with high levels of enantioselectiv-ity (92-98% ee). A representative transformation of the amination product to a biologically important 1,3,4-oxadiazol-2(3H)-one is achieved without any appreciable loss in enantioselectivity. Additionally, upon treatment with NaBH 3 CN, the amination product could also be converted into a biologically important thiazolidin-4-one derivative in good yield without any loss of stereochemical integrity.

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“…For example in 2013, Palomo and co-workers introduced 5 H -thiazol-4-ones as a new class of sulfur-containing pro-nucleophiles in a highly enantio- and diastereoselective conjugate addition to nitroalkenes, providing α,α-disubstituted α-mercapto carboxylic acids [5]. Since then, several asymmetric variants using 5 H -thiazol-4-ones as nucleophiles have been disclosed; such as amination [6], allylation [7], conjugate addition to enones [8], and γ-addition with allenoates [9]. All these examples focused on nucleophilic addition reactions of the C5 atom of 5 H -thiazol-4-ones.…”

Section: Introductionmentioning

confidence: 99%

Highly chemo-, enantio-, and diastereoselective [4 + 2] cycloaddition of 5H-thiazol-4-ones with N-itaconimides

Qiu¹,

Tan²

2016

Beilstein J. Org. Chem.

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Highly enantioselective construction of tertiary thioethers and alcohols via phosphine-catalyzed asymmetric γ-addition reactions of 5H-thiazol-4-ones and 5H-oxazol-4-ones: scope and mechanistic understandings

Abstract: A new method for facile access to enantioenriched tertiary thioethers/alcohols.

Cited by 118 publications

References 139 publications

Importance of Intermolecular Hydrogen Bonding for the Stereochemical Control of Allene–Enone (3+2) Annulations Catalyzed by a Bifunctional, Amino Acid Derived Phosphine Catalyst

Importance of Intermolecular Hydrogen Bonding for the Stereochemical Control of Allene–Enone (3+2) Annulations Catalyzed by a Bifunctional, Amino Acid Derived Phosphine Catalyst

Organocatalytic Enantioselective α‐Amination of Thiazol‐4‐one‐5‐carboxylates with Azodicarboxylates

Highly chemo-, enantio-, and diastereoselective [4 + 2] cycloaddition of 5H-thiazol-4-ones with N-itaconimides

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