Asymmetric Synthesis of Nonracemic Primary Amines via Spiroborate-Catalyzed Reduction of Pure (E)- and (Z)-O-Benzyloximes: Applications toward the Synthesis of Calcimimetic Agents

Ou, Wenhua; Espinosa, Sandraliz; Meléndez, Héctor J.; Farré, Silvia M.; Alvarez, Jaime L.; Torres, Valerie; Martínez, Ileanne; Santiago, Kiara M.; Ortiz-Marciales, Margarita

doi:10.1021/jo400371x

Cited by 16 publications

(15 citation statements)

References 109 publications

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“…[ α ] D 25 = –22.1 ( c = 1, methanol). The spectroscopic data and the optical rotation are in agreement with those in the literature . GC method [(injector: 200 °C; flow rate: 2 mL min –1 ; temperature: program 100 °C (hold 2 min), 130 °C at a rate of 1 °C min –1 (hold 5 min); 170 °C at a rate of 2 °C min –1 (hold 5 min)]: t R = 58.219 min.…”

Section: Methodssupporting

confidence: 86%

Stereoselective Metal‐Free Reduction of Chiral Imines in Batch and Flow Mode: A Convenient Strategy for the Synthesis of Chiral Active Pharmaceutical Ingredients

et al. 2016

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The convenient, metal‐free reduction of imines that contain an inexpensive and removable chiral auxiliary allowed for the synthesis of the immediate precursors of chiral active pharmaceutical ingredients (APIs). This protocol was carried out under batch and flow conditions to give the correspoding products in high yields with almost complete stereocontrol. In the presence of trichlorosilane, an inexpensive and nontoxic reducing agent, and an achiral Lewis base such as N,N‐dimethylformamide, the formal syntheses of Rivastgmine, calcimimetic NPS R‐568, and a Rho kinases inhibitor were successfully accomplished. For the first time, both the diastereoselective imine reduction and the auxiliary removal were efficiently performed in a micro‐ or mesoreactor under continuous‐flow conditions, which paved the way towards the development of a practical process for the syntheses of industrially relevant, biologically active, enantiopure N‐alkylamines.

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Section: Methodssupporting

confidence: 86%

Stereoselective Metal‐Free Reduction of Chiral Imines in Batch and Flow Mode: A Convenient Strategy for the Synthesis of Chiral Active Pharmaceutical Ingredients

et al. 2016

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“…17 Spiroaminoborate ester 1a , derived from diphenyl prolinol and ethylene glycol, has been demonstrated to be a highly stable and a convenient catalyst for the borane reduction of a variety of aryl, heteroaryl, α-alkoxy and aliphatic ketones providing the desired chiral secondary alcohols with a CBS oxazaborolidine-like enantioselectivity. 18 As illustrated in Scheme 2, we recently reported a useful protocol for the borane-mediated reduction of 2-haloketones 2 catalyzed by the spiroaminoborate 1a to obtain enantiopure aryl and aliphatic ( S )-halohydrines 3 , which upon subsequent cyclization with NaOH, gave the corresponding chiral oxiranes 4 .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of enantiopure 1,2-azido and 1,2-amino alcohols via regio- and stereoselective ring-opening of enantiopure epoxides by sodium azide in hot water

Wang

Huang

Jesús

et al. 2016

Tetrahedron: Asymmetry

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A practical and convenient method for the efficient and regio- and stereoselective ring-opening of enantiopure monosubstituted epoxides by sodium azide under hydrolytic conditions is reported. The ring–opening of enantiopure styryl and pyridyl (S)-epoxides by N3− in hot water takes place preferentially at the internal position with complete inversion of configuration to produce (R)-2-azido ethanols with up to 99% enantio- and regioselectivity, while the (S)-adamantyl oxirane provides mainly the (S)-1-adamantyl-2-azido ethanol in excellent yield. In general, 1,2-amino ethanols were obtained in high yield and excellent enantiopurity by the reduction of the chiral 1,2-azido ethanols with PPh3 in water/THF, and then converted into the Boc or acetamide derivatives.

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“…Starting materials of oximes were prepared according to previously reported methods. 15 General Procedure for Thiazole Products 3. Oxime 1 (0.5 mmol), anhydride 2 (1.5 mmol), CuI (10 mol%), KSCN (1.0 mmol), in toluene (3 mL) were added to a 25 mL Schlenk tube with magnetic stirrer bar.…”

mentioning

confidence: 99%

Access to Thiazole via Copper-Catalyzed [3+1+1]-Type Condensation Reaction under Redox-Neutral Conditions

et al. 2016

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A new strategy for thiazoles via copper-catalyzed [3+1+1]-type condensation reaction from oximes, anhydrides and potassiumthiocyanate (KSCN) is developed herein. The transformation has good functional group tolerance and various thiazoles were formed smoothly in good to excellent yields under mild reaction conditions. This process involves copper-catalyzed N-O/C-S bond cleavages, activation of vinyl sp C-H bond, and C-S/C-N bond formations which are under redox-neutral conditions as well as operational simplicity.

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Asymmetric Synthesis of Nonracemic Primary Amines via Spiroborate-Catalyzed Reduction of Pure (E)- and (Z)-O-Benzyloximes: Applications toward the Synthesis of Calcimimetic Agents

Cited by 16 publications

References 109 publications

Stereoselective Metal‐Free Reduction of Chiral Imines in Batch and Flow Mode: A Convenient Strategy for the Synthesis of Chiral Active Pharmaceutical Ingredients

Stereoselective Metal‐Free Reduction of Chiral Imines in Batch and Flow Mode: A Convenient Strategy for the Synthesis of Chiral Active Pharmaceutical Ingredients

Synthesis of enantiopure 1,2-azido and 1,2-amino alcohols via regio- and stereoselective ring-opening of enantiopure epoxides by sodium azide in hot water

Access to Thiazole via Copper-Catalyzed [3+1+1]-Type Condensation Reaction under Redox-Neutral Conditions

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