Decarboxylation studies on 3,5-dihydroxyhomophthalic acid derivatives

Hurd, Richard N.; Shah, D. H.

doi:10.1021/jo00943a043

Cited by 8 publications

(4 citation statements)

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“…The configuration of 25 is defined by the presence of the lactone bridge. Diester 25 was converted by Dieckmann condensation [25] to a mixture of isomeric p-ketoesters, which furnished after hydrolysis and decarboxylation the keto-lactone 26 in 67% yield.…”

Section: ' )mentioning

confidence: 99%

Planarization of Tetracoordinate Carbon Atom. Synthesis of 13‐oxa‐14‐oxo‐pentacyclo [5.5.2.1.0^4,150^10,15]pentadecane, a bridged ‘tetraquinacane’ preliminary communication

Keese

Pfenninger

Roesle

1979

Helvetica Chimica Acta

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SummaryStructural aspects of planoid deformation of tetracoordinate carbon atom, particularly those in annulenes with central carbon atom are discussed. [ 12lAnnulene 11 with central carbon atom is proposed as compound with strong planoid deformation around the internal carbon centre. The synthesis of a saturated precursor 15 is described.The theory of Van't Hoffand Le Be1 requires 4 equal ligands of a tetracoordinate carbon atom to be arranged as a tetrahedron [ l ] [2]. Although the tenet is basic to organic chemistry, no test has been made of how far planoid deformation without bond breaking is possible. Experimental evidence has shown that racemization of chiral carbon compounds does not occur without breaking a bond 131.The bonding and energetic situation of tetracoordinate tetrahedral as well as of planar carbon atom has been discussed extensively [4] [5]. In tetrahedrally coordinated carbon compounds the bonds can be described as being formed from one 2s and three 2 p orbitals and an appropriate linear combination of ligand orbitals, giving rise to 4 bonding molecular orbitals, each occupied by 2 electrons, and 4 antibonding ones. For planar coordination the central carbon atom can only use one 2s and two 2 p atomic orbitals for a-bonding to the 4 ligands giving rise to 3 orbitals. occupied by 6 electrons. The orthogonal nonbonding 2p orbital is occupied by the remaining 2 electrons (Fig. I ) .According to this bonding model, the difference in stability between the tetrahedral and the planar configuration is mainly due to the increasing energy of one of the 3 degenerate (T,) MO's, which is correlated with the 2p-A0 of A,,-symmetry in the square planar form. This suggests in terms of average C-H bond energies that the planar arrangement should be roughly 80-100 kcal/mol less stable than tetrahedrally coordinated carbon atom. It is thus not too surprising that autoracemization without bond breaking has not been observed. I)

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Section: ' )mentioning

confidence: 99%

Planarization of Tetracoordinate Carbon Atom. Synthesis of 13‐oxa‐14‐oxo‐pentacyclo [5.5.2.1.0^4,150^10,15]pentadecane, a bridged ‘tetraquinacane’ preliminary communication

Keese

Pfenninger

Roesle

1979

Helvetica Chimica Acta

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“…Ascending tic was conducted on silica gel supported on 20 cm long plastic sheets (type 6061 with fluorescent indicator from Eastman). Solvent systems for tic: (1) 1-butanolpyridine-0.1 TV acetic acid, 5:3:11 (upper phase); (2) ethyl acetatepyridine-acetic acid-water, 5:5:1:3; (3) isoamyl alcohol-pyridinewater, 7:7:6; (4) 2-propanol-l TV ammonia, 2:1; (5) 2-propanol-l TV acetic acid, 2:1; (6) 1-butanol-acetic acid-water, 4:1:5 (upper phase). Uv, I2 (always positive), ninhydrin spray (always negative), and Pauly reagent30 were successively used in all cases.…”

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confidence: 99%

“…After it was eluted from CMC by the usual procedure, the product (75 mg) was applied on a partition chromatography column (system 6) and was obtained in between 3.1 and 3.8 w: yield 15%, amino acid analysis, Glu 0.95, His 0.93, Trp 0.72, Ser 0.86, Tyr 0.96, Gly 0.95, Leu 1.00, NH31.03; [a]32D -23.5°(c 1). <Glu-His-Trp-Ser-Tyr-Gly-NH2 (5) des-(Leu7-Gly10)-LRF.…”

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confidence: 99%

Synthetic luteinizing hormone releasing factor analogs. Series of short-chain amide LRF homologs converging to the amino terminus

Rivier¹,

Vale²,

Burgus³

et al. 1973

J. Med. Chem.

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“…A ninhydrin test12 after each coupling was seldom found to be positive; when it was positive, a second coupling with the same BOC amino acid was performed; alternatively, acylation with acetic anhydride in CH2C12 was employed to Table I. Synthetic LRF and LRF Analogs < Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2-(LRF) (1) <Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pto-NHj-des-Gly l0-LRF (2) <Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-NH3-des-(Pro9-Gly10)-LRF (3) <Glu-His-Trp-Ser-Tyr-Gly-Leu-NH2-des-(Arg8-Gly10)-LRF (4) <Glu-His-Trp-Ser-Tyr-Gly-NH3-des-(Leu7-Gly10)-LRF (5) <Glu-His-Trp-Ser-Tyr-NH3-des-(Gly6-Gly 10)-LRF (6) < Glu-His-Trp-Ser-NH3-des-(Tyr S-Gly10 )-LRF ( 7…”

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confidence: 99%

Total synthesis of the macrolide, (R,S)-zearalanone

Hurd¹,

Shah²

1973

J. Med. Chem.

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Decarboxylation studies on 3,5-dihydroxyhomophthalic acid derivatives

Cited by 8 publications

References 1 publication

Planarization of Tetracoordinate Carbon Atom. Synthesis of 13‐oxa‐14‐oxo‐pentacyclo [5.5.2.1.0^4,150^10,15]pentadecane, a bridged ‘tetraquinacane’ preliminary communication

Planarization of Tetracoordinate Carbon Atom. Synthesis of 13‐oxa‐14‐oxo‐pentacyclo [5.5.2.1.0^4,150^10,15]pentadecane, a bridged ‘tetraquinacane’ preliminary communication

Synthetic luteinizing hormone releasing factor analogs. Series of short-chain amide LRF homologs converging to the amino terminus

Total synthesis of the macrolide, (R,S)-zearalanone

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Decarboxylation studies on 3,5-dihydroxyhomophthalic acid derivatives

Cited by 8 publications

References 1 publication

Planarization of Tetracoordinate Carbon Atom. Synthesis of 13‐oxa‐14‐oxo‐pentacyclo [5.5.2.1.04,15010,15]pentadecane, a bridged ‘tetraquinacane’ preliminary communication

Planarization of Tetracoordinate Carbon Atom. Synthesis of 13‐oxa‐14‐oxo‐pentacyclo [5.5.2.1.04,15010,15]pentadecane, a bridged ‘tetraquinacane’ preliminary communication

Synthetic luteinizing hormone releasing factor analogs. Series of short-chain amide LRF homologs converging to the amino terminus

Total synthesis of the macrolide, (R,S)-zearalanone

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Planarization of Tetracoordinate Carbon Atom. Synthesis of 13‐oxa‐14‐oxo‐pentacyclo [5.5.2.1.0^4,150^10,15]pentadecane, a bridged ‘tetraquinacane’ preliminary communication

Planarization of Tetracoordinate Carbon Atom. Synthesis of 13‐oxa‐14‐oxo‐pentacyclo [5.5.2.1.0^4,150^10,15]pentadecane, a bridged ‘tetraquinacane’ preliminary communication