Stereoselective synthesis of 4-substituted cis-3-(α-hydroxyethyl)-pyrrolidine-2-ones

Bartels, A.; Jones, Peter G.; Liebscher, Jürgen

doi:10.1016/s0957-4166(97)00113-4

Cited by 11 publications

(6 citation statements)

References 4 publications

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“…Chiral 5-alkenyl-1,3-dioxan-4-ones react with nitromethane at the exocyclic double bond in the presence of DBU with respectable diastereoselectivity. Attack of the nitronate anion occurs selectively at the re face, providing adduct 34 as the major stereoisomer (Scheme ) 12 …”

Section: Diastereoselective Conjugate Additionsmentioning

confidence: 99%

Conjugate Additions of Nitroalkanes to Electron-Poor Alkenes: Recent Results

et al. 2005

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Section: Diastereoselective Conjugate Additionsmentioning

confidence: 99%

Conjugate Additions of Nitroalkanes to Electron-Poor Alkenes: Recent Results

et al. 2005

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“…The product was purified by crystallization (t-BuOMe/hexane 1 : 1) to give 4.307 g (75%) of 17. (7), 104 (9). Crystals suitable for X-ray crystalstructure analysis were obtained from THF.…”

Section: Experimental Partmentioning

confidence: 99%

“…They prepared the alkylidene or arylidene dioxanones 12 by a formal aldol condensation of 13 with aldehydes (Scheme 4) [5]. In the next step, the Michael addition of MeNO 2 afforded the nitro lactones 14 with the selectivities shown in Scheme 4 [9]. Upon hydrogenation, the preferred products yielded the cis-configured g-lactams 15.…”

mentioning

confidence: 99%

Stereoselective Access to γ‐Nitro Carboxylates, Precursors for Highly Functionalized γ‐Lactams

Meisterhans

Linden

Hesse

2003

Helvetica Chimica Acta

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A straightforward synthesis of the enantiomerically pure nitro derivatives 31 and epi-32, which are particularly useful intermediates for the synthesis of highly functionalized g-lactams, is presented. ()-(R)-3-Hydroxy-3-phenylpropanoic acid (20) and its ethyl ester 25 were prepared from ()-l-mandelic acid (21). Condensation of 20 with pivalaldehyde furnished the novel enantiomerically pure 1,3-dioxan-4-one 17, the absolute configuration of which was established by X-ray crystal-structure analysis. Treating the lithium enolate of 17 with the nitro alkene 18 led, in a Michael-type addition, to a 1 : 1 mixture of two diastereoisomeric products. The stereocontrol of the addition was limited to the novel stereogenic center next to the lactone function. When the lithium enolate of 25 was treated with 18, the same selectivity was observed but with a lower chemical yield. Very facile separation of the isomers was achieved later in the synthetic sequence, when one isomer cyclized selectively to the nitro lactone 31, while the other one was isolated as hydroxy ester epi-32. The relative configuration of racemic epi-32 could be established by X-ray crystal-structure analysis.Introduction. ± In the course of our investigations on the total synthesis of caesalpinine A (1; Scheme 1) [1], a cyclic spermidine alkaloid [2], we were interested in finding an easy access to the lactam 2. The nitro ester 3 was assumed to be a useful precursor to 2, as it should undergo lactamization as soon as the NO 2 group is reduced. In 1979, Fra¬ter had found that b-hydroxybutyrate 4 can be alkylated with high diastereoselectivity, when its corresponding enolate is treated with alkyl bromides (Scheme 2) [3]. Seebach and co-workers applied this method for nitro alkenes 5 as alkylating agents [4]. Subsequent hydrogenation of the NO 2 groups afforded the corresponding g-lactams through spontaneous cyclization of the in situ formed amino esters. The configuration of the novel stereogenic center in the a-position to the ester was in agreement with the findings of Fra¬ter. The stereoselectivity can be explained by

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“…A single crystal of 4e with the dimensions 0.60 × 0.28 × 0.20 mm was measured on a STOE Ipds diffractometer using Mo-K α radiation (λ = 0.71073 Å). Crystal data: C 17 H 17 NO 2 S, M = 299.38, monoclinic space group P2 1 , a = 5.4491 (11), b = 8.7088 (15), c = 14.951 (3) Å, α = 90, β = 94.31 (3), γ = 90Њ, V = 707.5 (2) Å 3 , Z = 2, D c = 1.405 g cm Ϫ3 , F(000) = 316, µ(Mo-K α ) = 0.233 mm Ϫ1 . At 180 (2) K in the range of 2.71Њ < θ < 25.24Њ, 4743 reflections were measured, 2541 were unique (R (int) = 0.0382).…”

Section: Crystal Structure Determination Of Compound 4e 17mentioning

confidence: 99%

“…11-13 These ylidenedioxanones present a chiral Michael system which can undergo asymmetric 1,4-additions of cuprates, 13 silanes 14 and nitromethane. 15 These additions as well as the epoxidation of the double bond occurred from the Re-face. On the other hand, diazomethane approaches the C-C-double bond of 5-ylidene-dioxan-4-ones from the Si-face.…”

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confidence: 99%