Totalsynthese von (±)‐Bonellin‐dimethylester

Montforts, Franz‐Peter; Schwartz, Ulrich

doi:10.1002/jlac.1991199101126

Cited by 31 publications

(14 citation statements)

References 66 publications

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“…[35,36] Bonellin-dimethylester has also been the subject of extensive nuclear magnetic resonance studies. [37] The NMR spectrum possesses fine structure at low temperature due to nonequivalent free-base hydrogens, while at room temperature only one free-base hydrogen NMR resonance is found.…”

Section: Introductionmentioning

confidence: 99%

An Ab Initio Study of Structure and Energetics of Free-Base Bonellin-Dimethylester Isomers and Transition States

Sundholm¹,

Konschin²,

Häser

1999

Chem. Eur. J.

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The molecular structures of bonellin-dimethylester isomers and transition states, for the hydrogen migration of the inner hydrogens, have been optimized at density functional level by the use of split-valence basis sets augmented with polarization functions. Accurate values for the relative energies of the six isomers and the eight transition states have been obtained by performing second-order Mùller ± Plesset calculations. The isomer energies obtained at density functional level are 2 ± 5 kcal mol À1 smaller than second-order Mùller ± Plesset values, while the isomer energies calculated at Hartree ± Fock level are typically 1 kcal mol À1 too small compared with second-order Mùl-ler ± Plesset values, except for one isomer whose Hartree ± Fock energy is 7 kcal mol À1 larger. Compared with the second-order Mùller ± Plesset values, the energy barriers for the transition between the isomers calculated at density functional level are 3 ± 7 kcal mol À1 too small, whereas those obtained at Hartree ± Fock level are 6 ± 8 kcal mol À1 too large. Nuclear magnetic shielding constants calculated at Hartree ± Fock level are also reported. The calculated nuclear magnetic shieldings are used for analyzing the aromaticity and the aromatic pathway of the porphyrin nucleus.

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Section: Introductionmentioning

confidence: 99%

An Ab Initio Study of Structure and Energetics of Free-Base Bonellin-Dimethylester Isomers and Transition States

Sundholm¹,

Konschin²,

Häser

1999

Chem. Eur. J.

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“…Occasionally the bases are suitable for E 2 -elimination reactions; 52−54 because of their low sensitivity to oxidation (particularly with t-Bu-P 1 ) they can be the exclusive reagents for nonreductive hydrogen halide eliminations in strongly electrophilic polyhalides (eq 8).Reactions with Carbonyl Electrophiles. The bases catalyze the reaction of dialkyl phosphites with aldehydes, 55 aldol condensations,56 and aldol additions of benzophenone imine glycine ester (eq 9). 30 Michael Additions Including Reactions with Heteronucleophiles.…”

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confidence: 99%

(tert-Butylimino)tris(pyrrolidino)phosphorane (BTPP)

Schwesinger¹

2007

Encyclopedia of Reagents for Organic Synthesis

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“…Thiolactam 10 was transformed by the sulfide contraction method 3,22,23 into the target compound 12. Thiolactam 10 reacted with bromo malonic diester 11 [24][25][26] in the presence of DBU to yield coupling product 13. Crude 13 was heated in triethyl phosphite for sulfur extrusion and contracted diester intermediate was allowed to react further without purification to give 12 with allyl ester cleavage and decarboxylation.…”

Section: Resultsmentioning

confidence: 99%

An enantiopure building block for naturally occurring hydroporphyrins and vitamin B12 from Hagemann´s ester

Tien¹,

Panek-Bryla²,

Gögüs³

et al. 2020

Arkivoc

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Enantiomerically pure ring building block for naturally occurring hydroporphyrins and possibly vitamin B12 was synthesized starting from methylated Hagemann´s ester. Originally, this ester was utilized to investigate preparation of ring building blocks for vitamin B12 in Eschenmoser´s and Woodward´s syntheses. Hagemann´s ester furnished methyl 4-acetoxy-2,3-dimethylcyclohex-2-en-1-carboxylate in racemic form. Kinetic enzymatic resolution of the cyclohexene acetate led to the enantiopure hydroporphyrin building block methyl {(1S,2S,5S,3Z)-3-(2-t-butoxy-2-oxoethylidene)-1. 5-dimethyl-7-oxo-4-aza-6-oxabicyclo[3.3.0]oct-2-yl}-2-propionate. O CO 2 CH 3 CO 2 CH 3 OH N H O CO 2 CH 3 O CO 2 tBu CO 2 CH 3 OAc

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Totalsynthese von (±)‐Bonellin‐dimethylester

Cited by 31 publications

References 66 publications

An Ab Initio Study of Structure and Energetics of Free-Base Bonellin-Dimethylester Isomers and Transition States

An Ab Initio Study of Structure and Energetics of Free-Base Bonellin-Dimethylester Isomers and Transition States

(tert-Butylimino)tris(pyrrolidino)phosphorane (BTPP)

An enantiopure building block for naturally occurring hydroporphyrins and vitamin B12 from Hagemann´s ester

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