Pyridyl and Furyl Epoxides of More Than 99% Enantiomeric Purities: The Use of a Phosphazene Base

Solladié‐Cavallo, Arlette; Roje, Marin; Isarno, Thomas; Šunjić, Vitomir; Vinković, Vladimir

doi:10.1002/(sici)1099-0690(200003)2000:6<1077::aid-ejoc1077>3.0.co;2-4

Cited by 68 publications

(43 citation statements)

References 23 publications

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“…6g,43 1 H NMR data (See Supporting Information) are in agreement with those previously reported. 43 HPLC (OD-H, 10% i- PrOH/hexane): 9.0 min (R), 15.4 min (S) .…”

Section: Experimental Partsupporting

confidence: 90%

“…6g,43 1 H NMR data (See Supporting Information) are in agreement with those previously reported. 43 HPLC (OD-H, 10% i- PrOH/hexane): 9.0 min (R), 15.4 min (S) . Propionate ester: 1 H NMR (300 MHz, CDCl 3 ): δ 8.54 (m, 1H), 7.56 (td, J 1 = 7.8 Hz, J 2 = 1.8 Hz, 1H), 7.38-7.26 (m, 5H), 7.14-7.09 (m, 2H), 6.20 (dd, J 1 = 9.0 Hz, J 2 = 5.4 Hz, 1H), 3.41-3.20 (m, 2H), 2.25 (q, J = 7.8 Hz, 2H), 1.02 (t, J = 7.2 Hz, 3H); 13 C NMR (75 MHz, CDCl 3 ): δ 173.5, 157.7, 149.6, 140.6, 136.4, 128.7, 128.2, 126.7, 124.1, 121.9, 75.5, 45.6, 27.9, 9.2; IR (KBr, cm −1 ) 3033, 2980, 2941, 1737, 1182, 763, 700; MS : HR-ESI calculated for C 16 H 17 NNaO 2 + (M+Na + ): 278.1151; found: 278.1152.…”

Section: Experimental Partsupporting

confidence: 90%

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Kinetic Resolution of Secondary Alcohols Using Amidine-Based Catalysts

et al. 2012

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Kinetic resolution of racemic alcohols has been traditionally achieved via enzymatic enantioselective esterification and ester hydrolysis. However, there has long been considerable interest in devising nonenzymatic alternative methods for this transformation. Amidine-Based Catalysts (ABCs), a new class of enantioselective acyl transfer catalysts developed in our group, have demonstrated, inter alia, high efficacy in the kinetic resolution of benzylic, allylic and propargylic secondary alcohols and 2-substituted cycloalkanols, and thus provide a viable alternative to enzymes.

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“…6g,43 1 H NMR data (See Supporting Information) are in agreement with those previously reported. 43 HPLC (OD-H, 10% i- PrOH/hexane): 9.0 min (R), 15.4 min (S) .…”

Section: Experimental Partsupporting

confidence: 90%

Section: Experimental Partsupporting

confidence: 90%

Kinetic Resolution of Secondary Alcohols Using Amidine-Based Catalysts

et al. 2012

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“…Of the resulting ylide conformations, 25a will be strongly preferred and will react on the more open Re face, since the Si face is blocked by the gem-dimethyl group (Scheme 1.9) [3,15].…”

Section: Discussion Of Factors Affecting Diastereo-and Enantioselectimentioning

confidence: 99%

Asymmetric Synthesis of Epoxides and Aziridines from Aldehydes and Imines

Aggarwal¹,

Badine²,

Moorthie³

2006

Aziridines and Epoxides in Organic Synthesis

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Epoxides and aziridines are strained three-membered heterocycles. Their synthetic utility lies in the fact that they can be ring-opened with a broad range of nucleophiles with high or often complete stereoselectivity and regioselectivity and that 1,2-difunctional ring-opened products represent common motifs in many organic molecules of interest. As a result of their importance in synthesis, the preparation of epoxides and aziridines has been of considerable interest and many methods have been developed to date. Most use alkenes as precursors, these subsequently being oxidized. An alternative and complementary approach utilizes aldehydes and imines. Advantages with this approach are: i) that potentially hazardous oxidizing agents are not required, and ii) that both C-X and C-C bonds are formed, rather than just C-X bonds (Scheme 1.1).This review summarizes the best asymmetric methods for preparing epoxides and aziridines from aldehydes (or ketones) and imines. Asymmetric Epoxidation of Carbonyl CompoundsThere have been two general approaches to the direct asymmetric epoxidation of carbonyl-containing compounds (Scheme 1.2): ylide-mediated epoxidation for the construction of aryl and vinyl epoxides, and a-halo enolate epoxidation (Darzens reaction) for the construction of epoxy esters, acids, amides, and sulfones.

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“…The corresponding ylide was formed by the aid of sodium hydride and the epoxidation was carried out at low temperature to afford trans-diaryl epoxides 27 with good stereoselctivity and high enantioselectivity with recovery of the chiral sulfide 25. The use of a phosphazene base (EtP 2 ) resulted in rapid ylide formation and allowed the preparation of aryl-vinyl epoxides 30 and heteroaromatic aryl-epoxides 31 in good chemical yield and high stereo-and enantioselectivity.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and elaboration of trans 2,3-diaryloxiranes

Bonini¹,

Lupattelli²

2008

Arkivoc

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2,3-Diaryloxiranes represent challenging intermediates for both their preparation and synthetic elaboration. Provided their synthesis in enantiopure form, they can be considered as suitable starting material for the synthesis of functionalized 1,2-diarylethanols, which are easily found in chiral auxiliaries, ligands and organocatalysts. The most efficient asymmetric methods for their preparation and synthetic elaboration are herein described. Regio-and stereoselective ring opening reactions, as reduction, nucleophilic opening with halides and oxygen nucleophiles have allowed straightforward access to versatile chiral intermediates such as aniline alcohols, halohydrins and 1,3-dioxolanes, their transformation affords chiral bases and bi-or tridentate ligands to use in asymmetric synthesis.

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Pyridyl and Furyl Epoxides of More Than 99% Enantiomeric Purities: The Use of a Phosphazene Base

Cited by 68 publications

References 23 publications

Kinetic Resolution of Secondary Alcohols Using Amidine-Based Catalysts

Kinetic Resolution of Secondary Alcohols Using Amidine-Based Catalysts

Asymmetric Synthesis of Epoxides and Aziridines from Aldehydes and Imines

Synthesis and elaboration of trans 2,3-diaryloxiranes

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