Stereocontrolled construction of rigid tricyclic bis(Î±-amino acid) derivatives by Ru(Ii)-catalyzed cascade and Dielsâ€“Alder reactions

Efskind, Jon; Rømming, Christian; Undheim, Kjell

doi:10.1039/b103254m

Cited by 22 publications

(12 citation statements)

References 40 publications

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“…The spectroscopic data agree with previously published results. [2] n-Butyllithium (2.5 M in hexane, 21.6 mL, 54.1 mmol, 1.0 equiv.) was added dropwise to a solution of the silyl ether S-2 (9.97 g, 54.1 mmol, 1.0 equiv.)…”

Section: Further Control Reactionsmentioning

confidence: 99%

“…The spectroscopic data agree with previously published results. [2] Ni(OAc)24H2O (1.13 g, 4.54 mmol, 10 mol%) was dissolved in EtOH (95%, 67 mL). H2 was passed through the reaction mixture for 10 min before a solution of NaBH4 (1 M in abs.…”

Section: Further Control Reactionsmentioning

confidence: 99%

“…Several transformations like the -, -, and functionalization of carbonyl compounds are carried out under enamine-, iminium-and dienamine activation. In addition, a growing number of cycloadditions, [2] including Diels-Alder reactions, [3] have been catalyzed by small organic molecules.…”

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confidence: 99%

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Dienamine-Induced Divinylcyclopropane-Cycloheptadiene Rearrangements

Apel¹,

Hartmann²,

Lentz³

et al. 2018

Preprint

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Sigmatropic rearrangements constitute an important group of pericyclic reactions. In contrast to cycloaddition reactions, examples of catalytic variants of electrocyclic reactions and sigmatropic rearrangements are still scarce in the chemical literature. Herein, we report the first organocatalytic Cope rearrangement of in situgenerated divinylcyclopropanes. The reactive motif is generated by condensation of 4-(2-vinylcyclopropyl)but-2-enal derivatives and a secondary amine catalyst to form a transient dienamine. The cycloheptadiene products can be obtained in high yield and excellent diastereoselectivity. Importantly, the reaction was demonstrated to be stereospecific, proceeds under mild conditions, and shows broad functional group tolerance.Scheme 1: Organocatalytic Claisen rearrangement by activation with urea derivatives (top). First organocatalytic Cope rearrangement by iminium activation (center). Planned transformation of vinyl-substituted cyclopropane but-2-enals to cycloheptadienals (bottom). , RSC Adv. 2012, 2, 5941-5943. Scheme 2. Conversion of an enantiopure 4-(2-vinylcyclopropyl)but-2-enal. Scheme 3. Conversion of ester 5p to lactone 7.Abstract: Pericyclic reactions represent an effective transformation in organic synthesis to generate complexity. However, this reaction class is seldomly presented in the context of organocatalysis. Herein, we present the first organocatalytic Cope rearrangement of in situ-generated divinylcyclopropanes. The reactive functionality is built up by condensation of 4-(2-vinylcyclopropyl)but-2-enal and secondary amine catalysts. The resulting cycloheptadienes were obtained in high yield and excellent diastereoselectivity while the reaction is stereospecific, proceeds under mild conditions, and shows broad functional group tolerance. Experimental Procedures General Working MethodsThe analytical data was obtained with the help of the following equipment. 1 H and 13 C NMR spectra were acquired on a JEOL ECX 400 (400 MHz), JEOL ECP 500 (500 MHz), Bruker Avance 500 (500 MHz), Varian Inova 600 (600 MHz) and a Bruker Avance 700 (700 MHz) in CDCl3 as solvent. The chemical shifts were reported relative to CDCl3 (δ = 1 H: 7.26 ppm, 13 C: 77.16 ppm). The multiplicities of the signals are described using the following abbreviations: s = singlet, d = doublet, t = triplet, q = quartet, p = quintuplet, br = broad. The spectra were evaluated with the software MestReNova 10.0.2. High resolution mass spectra were obtained on an ESI-FTICR-MS: Ionspec QFT-7 (Agilent/Varian), or a HR-EI-MS: Autospec Premier (Waters). Low resolution mass spectra (GC-MS) were recorded on a GC system Agilent Technologies 7890-A series/Mass selective detector, Agilent Technologies 5975 C (Säule: HP-5MS (J&W Scientific, Agilent); 30 m, 0.250 mm i.D., Film 0.25 μm).Enantiomeric ratios were determined by chiral HPLC (Agilent Series 1200 with DAD) or by GC (Agilent 7890B) on a chiral column. The specific conditions are given in each case. IR spectra were measured on a JASCO FT/IR-4100 spectrometer. Characteristic abs...

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Section: Further Control Reactionsmentioning

confidence: 99%

Section: Further Control Reactionsmentioning

confidence: 99%

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Dienamine-Induced Divinylcyclopropane-Cycloheptadiene Rearrangements

Apel¹,

Hartmann²,

Lentz³

et al. 2018

Preprint

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“…Our synthetic approach to the larger diyne nitriles 1l-n, potential precursors of scaffold G, is depicted in Scheme 5. Alcohol 24 19 and TsNHBoc were reacted under standard Mitsunobu conditions to give 25, from which the tosyl group was subsequently removed and replaced by a propargyl moiety. The tetrahydropyranyl residue was displaced under acidic conditions, and the resulting alcohol was submitted to a second Mitsunobu reaction with aminonitriles bearing SO 2 -2-pyridyl (29) 20 or nosyl (30) 21 protecting group at the nitrogen atom, yielding diyne nitriles 1l and 1m, respectively.…”

Section: Figurementioning

confidence: 99%

Synthesis of Orthogonally Protected Angular Nitrogen Polyheterocycles via CpCo-Catalyzed Pyridine Formation

Miclo¹,

Garcia²,

Evanno³

et al. 2010

Synlett

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Unprecedented nitrogen polyheterocycles have been prepared by means of intramolecular Co-catalyzed [2+2+2] cycloaddition of two alkynes to one nitrile. They exhibit two nitrogencontaining rings fused in an angular fashion to one pyridine unit. Several relative positions of the nitrogen atoms have been studied, giving rise to eight different new scaffolds. In order to allow selective functionalization of the two amino groups, orthogonal protecting groups (PG 1 and PG 2 ) were introduced prior to cyclization. Eleven combinations of seven different protecting groups (Bn, COCF 3 , Cbz, Boc, Ts, SO 2 -2-py, Ns) were tested, most of them being perfectly tolerated under the cyclization conditions.

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“…In this report we describe methodology aimed at the construction of as -indacene-bridged bis(α-amino acid) derivatives by a Ru(II)-effected cascade reaction with an appropriate triyne as substrate. In a recent report we have described the preparation of tricyclic-bridged bis(α-amino acid) derivatives from ynedienes by a Diels−Alder reaction of the conjugated diene cascade products …”

Section: Introductionmentioning

confidence: 99%

Ru(II)-Catalyzed Cascade Reactions in Stereocontrolled Construction of Rigid as-Indacene-Bridged Bis(α-amino acid) Derivatives

et al. 2002

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The key construction in the preparation of as-indacene-bridged bis(alpha-amino acid) derivatives was effected by a Ru(II)-catalyzed RCM cascade reaction of appropriately substituted triynes. The latter were available after stepwise and stereocontrolled alkynylations of (2R)-2,5-dihydro-2-isopropyl-3,6-dimethoxypyrazine as chiral auxiliary. The regio- and stereochemical transformations have been verified by a single-crystal X-ray analysis.

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Stereocontrolled construction of rigid tricyclic bis(Î±-amino acid) derivatives by Ru(Ii)-catalyzed cascade and Dielsâ€“Alder reactions

Cited by 22 publications

References 40 publications

Dienamine-Induced Divinylcyclopropane-Cycloheptadiene Rearrangements

Dienamine-Induced Divinylcyclopropane-Cycloheptadiene Rearrangements

Synthesis of Orthogonally Protected Angular Nitrogen Polyheterocycles via CpCo-Catalyzed Pyridine Formation

Ru(II)-Catalyzed Cascade Reactions in Stereocontrolled Construction of Rigid as-Indacene-Bridged Bis(α-amino acid) Derivatives

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