Observations on the DDQ Oxidation of 1-Acyldihydropyridines - A Synthetic Application

Wallace, Debra J.; Gibb, Andrew D.; Cottrell, Ian F.; Kennedy, Derek J.; Brands, Karel M. J.; Dolling, Ulf H.

doi:10.1055/s-2001-17509

Cited by 29 publications

(15 citation statements)

References 3 publications

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“…[55][56][57][58][59][60][61] Similar behaviour was observed for most of the carboxylic acid substituted dihydropyridines here. Aside from those bearing a quaternary carbon atom at C-4, dihydropyridines of the general structure 12 underwent fast degradation at room temperature, producing the substituted pyridines through decarboxylation/demethoxycarbonylation.…”

Section: Miscellaneous: Air and Lead Tetraacetate Oxidation Reactionssupporting

confidence: 81%

“…For the pentenoic acid derived ketene acetal 7n a 3:1 mixture of the C-2 and C-4 addition products 54n and 55n (95 % yield), each as two diastereoisomers, was isolated (Scheme 19). Scheme 18. Isoquinoline (56) in turn gave, as expected, only the C-1 addition products with 7a, 7b and 7d. At room temperature these exist either as two rotamers (in the case of 57a, R 1 = R 2 = H) or, for bulky substituents such as in 57b (R 1 = R 2 = Me), as single rotamers (Scheme 20).…”

Section: Reactions Of Bis(trimethylsilyl)ketene Acetals With Quinolinmentioning

confidence: 58%

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Bis(trimethylsilyl)ketene Acetals as C,O‐Dinucleophiles: One‐Pot Formation of Polycyclic γ‐ and δ‐Lactones from Pyridines and Pyrazines

Rudler

Denise

et al. 2005

Eur J Org Chem

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Bis(trimethylsilyl)ketene acetals react with pyridines, quinoline and isoquinoline in the presence of stoichiometric amounts of methyl chloroformate to give the corresponding dihydropyridine-, dihydroquinoline-and dihydroisoquinoline-substituted carboxylic acids in satisfactory yields. The regio-and diastereoselectivities of the addition reactions, together with the presence or absence of rotamers, have been established. The isolated acids react with peracids to give β-hydroxy-δ-lactones through an intramolecular reaction. Similar lactonizations could also be brought about directly from the azaaromatic compounds in one-pot reactions with silica

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Section: Miscellaneous: Air and Lead Tetraacetate Oxidation Reactionssupporting

confidence: 81%

Section: Reactions Of Bis(trimethylsilyl)ketene Acetals With Quinolinmentioning

confidence: 58%

Bis(trimethylsilyl)ketene Acetals as C,O‐Dinucleophiles: One‐Pot Formation of Polycyclic γ‐ and δ‐Lactones from Pyridines and Pyrazines

Rudler

Denise

et al. 2005

Eur J Org Chem

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“…72 Additional mechanistic role of pyridine may involve production of an intermediate charge-transfer complex between pyridine and DDQ. 73 Charge-transfer complexes have been documented with electron rich nitrogen heterocycles including pyrimidines and imidazoles. 74 …”

Section: Resultsmentioning

confidence: 99%

Synthesis of a 35-Member Stereoisomer Library of Bistramide A: Evaluation of Effects on actin State, Cell Cycle and Tumor Cell Growth

et al. 2009

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Synthesis and preliminary biological evaluation of a 35-member library of bistramide A stereoisomers are reported. All eight stereoisomers of the C1-C13 tetrahydropyran fragment of the molecule were prepared utilizing crotylsilane reagents 9 and 10 in our [4+2]-annulation methodology. In addition, the four isomers of the C14-C18 γ-amino acid unit were accessed via a Lewis acid mediated crotylation reaction using both enantiomers of organosilane 11. The spiroketal subunit of bistramide A was modified at the C39-alcohol to give another point of stereochemical diversification. The fragments were coupled using standard peptide coupling protocol to provide 35 stereoisomers of the natural product. These stereochemical analogs were screened for their effects on cellular actin and cytotoxicity against cancer cell lines (UO-31 renal and SF-295 CNS). The results of these assays identified one analog, 1.21, with enhanced potency relative to the natural product, bistramide A.

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“…Also, free energy (+23.7 kcal/mol) of the reaction above cited seems too large (too endothermic). In spite of various experimental reports of DDQ reactions, their mechanisms are still veiled. To solve these questions, FMO (frontier molecular orbital) analyses and DFT calculations were performed in this work.…”

Section: Introductionmentioning

confidence: 99%

A DFT study of hydride transfers to the carbonyl oxygen of DDQ

Yamabe

Yamazaki

Sakaki

2015

Int J of Quantum Chemistry

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Hydride‐transfer reactions between benzylic substrates and 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) were investigated by DFT (density functional theory) calculations. The lowest unoccupied molecular orbital of DDQ has the largest extension on two carbonyl oxygens, which comes from two‐step mixing of antisymmetric orbitals of fragment π MOs. Transition‐state (TS) geometries and activation energies of reactions of four benzylic substrates R2CH2‐para‐C6H4R1 (R1, R2 = H and/or OCH3) with DDQ were calculated. M06‐2X/6‐311(+*)G* was found to be a practical computational method, giving energies and geometries similar to those of M06‐2X/6‐311++G(3df,2pd) and wB97xD/6‐311++G(3df,2pd). For toluene (R1 = R2 = H), an initiation‐propagation model was suggested, and the calculated kinetic isotope effect k(H)/k(D) = 5.0 with the tunnel correction at the propagating step is in good agreement with the experimental value 5.2. A reaction of para‐MeOC6H4CH2(OMe) + DDQ + (H2O)14 → para‐MeOC6H4C(O)H + HOMe + DDQH2 + (H2O)13 was investigated by M06‐2X/6‐311(+*)G*. Four elementary processes were found and the hydride transfer (TS1) is the rate‐determining step. The hydride transfer was promoted by association with the water cluster. The size of the water cluster, (H2O)n, at TS1 was examined. Three models of n = 14, 20, and 26 were found to give similar activation energies. Metal‐free neutral hydride transfers from activated benzylic substrates to DDQ were proposed to be ready processes both kinetically and thermodynamically. © 2015 Wiley Periodicals, Inc.

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Observations on the DDQ Oxidation of 1-Acyldihydropyridines - A Synthetic Application

Cited by 29 publications

References 3 publications

Bis(trimethylsilyl)ketene Acetals as C,O‐Dinucleophiles: One‐Pot Formation of Polycyclic γ‐ and δ‐Lactones from Pyridines and Pyrazines

Bis(trimethylsilyl)ketene Acetals as C,O‐Dinucleophiles: One‐Pot Formation of Polycyclic γ‐ and δ‐Lactones from Pyridines and Pyrazines

Synthesis of a 35-Member Stereoisomer Library of Bistramide A: Evaluation of Effects on actin State, Cell Cycle and Tumor Cell Growth

A DFT study of hydride transfers to the carbonyl oxygen of DDQ

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