Novel tetrahydroisoquinoline based organocatalysts for asymmetric Diels–Alder reactions: insight into the catalytic mode using ROESY NMR and DFT studies

Naicker, Tricia; Petzold, Katja; Singh, Thishana; Arvidsson, Per I.; Kruger, Hendrik G.; Maguire, Glenn E. M.; Govender, Thavendran

doi:10.1016/j.tetasy.2010.11.010

Cited by 29 publications

(24 citation statements)

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“…We decided to investigate the potential of TIQ derivatives as organocatalysts. Compound (I) has recently been synthesized and evaluated as a novel iminium-activated organocatalyst in an asymmetric Diels-Alder reaction (Naicker, Petzold et al, 2010). Compound (II) is novel and is the precursor to the same class of organocatalysts based on a (1R,3S)-6,7-dimethoxy-1-phenyl-1,2,3,4-tetrahydroisoquinoline backbone.…”

Section: Commentmentioning

confidence: 99%

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Optically active diaryl tetrahydroisoquinoline derivatives

et al. 2011

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In (1R,3S)-6,7-dimethoxy-3-(methoxydiphenylmethyl)-1-phenyl-1,2,3,4-tetrahydroisoquinoline, C 31 H 31 NO 3 , (I), and (1R,3S)-2-benzyl-3-[diphenyl(trimethylsiloxy)methyl]-6,7-dimethoxy-1-phenyl-1,2,3,4-tetrahydroisoquinoline, C 40 H 43 NO 3 Si, (II), the absolute configurations have been confirmed to be R and S at the isoquinoline 1-and 3-positions, respectively, by NMR spectroscopy experiments. Both structures have monoclinic (P2 1) symmetry and the N-containing six-membered ring assumes a half-chair conformation. The asymmetric unit of (I) contains one molecule, while (II) has two molecules within the asymmetric unit. These structures are of interest with respect to the conformation around the exocyclic CC bond: (I) displays an ap (antiperiplanar) conformation, while (II) displays an sc-exo (synclinal) conformation around this bond. These conformations are significant for stereocontrol when these compounds are used as catalysts. Various C-HÁ Á Á and C-HÁ Á ÁO bonds link the molecules together in the crystal structure of (I). In the crystal structure of (II), three intermolecular C-HÁ Á Á hydrogen bonds help to establish the packing.

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Section: Commentmentioning

confidence: 99%

“…The structural data demonstrated how we could improve the catalytic reactivity by reducing the steric bulk of the ligand. A successful catalyst was obtained by removing the phenyl moieties from (I) (Naicker, Petzold et al, 2010).…”

Section: Commentmentioning

confidence: 99%

Optically active diaryl tetrahydroisoquinoline derivatives

et al. 2011

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“…The applications of these TIQ catalysts include asymmetric transfer hydrogenation [1], high-pressure hydrogenation of unsymmetrical olefins [2], Henry type C-C bond formations [3] and as an organocatalyst in Diels-Alder reaction [4]. The title compound has been used as a precursor in the synthesis of several chiral ligands containing the TIQ framework.…”

Section: Discussionmentioning

confidence: 99%

Crystal structure of (S)-N-benzyl-1,2,3,4-tetrahydroisoquinoline-3-carboxamide, C17H20N2O2

Cele

Bhatt

Govender

et al. 2013

Zeitschrift Für Kristallographie - New Crystal Structures

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Source of materialTo a solution of (S)-benzyl-3-(benzylcarbamoyl)-3,4-dihydroisoquinoline-2(1H)-carboxylate in 50/50 MeOH/THF was added 10% palladium on carbon (one half equivalent). This solution was stirred under a hydrogen atmosphere (1 atm) for 2 h at room temperature. The crude product was obtained by filtering the Pd/C through a plug of Celite, the filtrate was then evaporated to dryness under reduced pressure. Purification was acheived with silica gel column chromatography (DCM/MeOH/10% NH 3 OH) in CHCl 3 = 87:3:10, R f = 0.4. The benzyl amide tetrahydroisoquinoline was isolated as a white solid (85% yield). Melting point = 356-358 K. Recrystallization from ethanol at room temperature afforded colourless crystals suitable for X-ray analysis. Experimental detailsAll H attached to carbon atoms and the hydrogen atom at N2 were positioned geometrically and allowed to ride on their respective parent atoms. The hydrogen atoms at O1S and at N1 were refined freely with individual U iso values. The absorption correction was based on fitting a function to the empirical transmission surface as sampled by multiple equivalent measurements (Bruker, 2008). The so-called Flack parameter (-0.1(7)) was calculated by a holein-one method [10,11]. DiscussionThe use of tetrahydroisoquinoline (TIQ) backbone for the synthesis of chiral catalysts is an ongoing interest in our research group. The applications of these TIQ catalysts include asymmetric transfer hydrogenation [1], high-pressure hydrogenation of unsymmetrical olefins [2], Henry type C-C bond formations [3] and as an organocatalyst in Diels-Alder reaction [4]. The title compound has been used as a precursor in the synthesis of several chiral ligands containing the TIQ framework. It was derived from commercially available starting materials S-phenyl glycine and formaldehyde. The absolute stereochemistry was confirmed to be S at the C9 position from proton NMR spectroscopy [5]. The Ncontaining six membered ring assumes a half-chair conformation [Q = 0.4556(10) Å, q = 48.80(14)°and f = 328.22 (18)] as seen from the crystal structure in which the C1-N1-C9-C8 bond has a torsion angle of -45.3(11)°. We have already reported this observation in analogous structures [6][7][8]. The molecules are linked together via hydrogen bonding with a water molecule resulting in a one dimensional polymer. The title compound also displays two weak C-H···p interactions (C7-H7a···p and C8-H8a···p). There are no p···p interactions within the crystal.

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“…7 The complexes of copper(II) acetate with the oxazolines derived from (S)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid were also successfully used as highly enantioselective catalysts for the Henry reaction (up to 77% ee). 10 It is known, that in analogy to the molecule of (S)-proline, also the molecule (S)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid possesses a rigid structure, and incorporation of this α-amino acid into a peptide chain allows preparation of peptides with well-defined tertiary structures. 9 Furthermore, functionalized esters of this acid catalyze the asymmetric Diels-Alder reaction of cinnamic aldehyde with cyclopentadiene (43% ee for the exo-product, 50% ee for the endo-product, in the ratio of for the exo:endo-product).…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of N-Substituted (S)-1,2,3,4-Tetrahydroisoquinoline-3-carboxamides and Thioamides as Organocatalysts for Asymmetric Aldol Reaction

Drabina¹,

Androvič²,

Panov³

et al. 2014

HETEROCYCLES

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In this paper, the preparation and characterization of eight optically pure N-functionalized (S)-1,2,3,4-tetrahydroisoquinoline-3-carboxamides and thioamides is described. The prepared amides and thioamides were tested as organocatalysts of aldol reaction of 4-nitrobenzaldehyde and acetone. The highest ee of formation of 4-hydroxy-4-(4-nitrophenyl)butan-2-one was obtained with (S)-N-[(1R)-1-phenylethyl]-1,2,3,4-tetrahydroisoquinoline-3-thiocarboxamide (77% ee). The observed deceleration of the aldol reaction catalyzed in this way, as compared with that catalyzed with (S)-proline, was attributed to the formation of little reactive cyclic intermediate, which was isolated and characterized.

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Novel tetrahydroisoquinoline based organocatalysts for asymmetric Diels–Alder reactions: insight into the catalytic mode using ROESY NMR and DFT studies

Cited by 29 publications

References 44 publications

Optically active diaryl tetrahydroisoquinoline derivatives

Optically active diaryl tetrahydroisoquinoline derivatives

Crystal structure of (S)-N-benzyl-1,2,3,4-tetrahydroisoquinoline-3-carboxamide, C17H20N2O2

Synthesis and Characterization of N-Substituted (S)-1,2,3,4-Tetrahydroisoquinoline-3-carboxamides and Thioamides as Organocatalysts for Asymmetric Aldol Reaction

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