Electrochemical oxidation of halomicin B to rifamycin S

Ganguly, Ashit K.; Kabasakalian, Peter; Kalliney, Sami; Sarre, Olga Z.; Szmulewicz, S.; Westcott, Anita

doi:10.1021/jo00869a040

Cited by 6 publications

(3 citation statements)

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“…Theoretical support to this mechanistic picture can be found in the results of a computational ab initio study we have recently reported, in which, among the three possible TOD diastereomers (Scheme ),6g cis -TOD-Oinside exhibits the highest proton affinity, way outside the range of O−C−O anomeric systems, which are known to be relatively weak bases,11a but similar to the stronger gauche O−C−C−O bases 11b. This is due, in large measure, to the strong intramolecular hydrogen bonds within the cavity of cis -TOD-Oinside (Scheme ).…”

Section: Resultsmentioning

confidence: 80%

On Five- vs Six-membered Diacetal Formation from Threitol and the Intermediacy of Unusually Stable Protonated Species¹

et al. 2000

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The long known, but hitherto poorly understood, thermodynamically controlled diacetalation of rac-threitol with alkylaldehydes provided bicyclic, cis-tetraoxadecalin (TOD) ("66") and bi(dioxolanyl) (BDO) ("55") products, shown to be formed in acid-concentration and temperature-dependent ratio. The configurational and conformational isomeric diacetals obtained in four such reactions of substituted aldehydes (RCHO, R = CH(3), CH(2)Cl, CH(2)Br, CO(2)CH(3)) with rac-threitol were isolated and characterized. A variable acid-concentration analysis of the equilibrium mixture of products in one such case (R = CH(2)Br) was performed and provided equilibrium constants and, hence, free-energy differences among these products and their relatively stable protonated intermediates. The latter were rationalized by the unusually high proton-affinity calculated for the cis-TOD ("66") form.

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Section: Resultsmentioning

confidence: 80%

On Five- vs Six-membered Diacetal Formation from Threitol and the Intermediacy of Unusually Stable Protonated Species¹

et al. 2000

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“…PhosphaneϪphosphonates are interesting potentially hemilabile ligands. Furthermore, using the TMSBr/H 2 O/ NaOH sequence of Roundhill et al, [19] phosphaneϪphosphonate 22, for instance, was converted into its disodium phosphonic salt 28 (Scheme 2). Scheme 2 In a CH 2 Cl 2 /water mixture (1:1, v/v), the salt 28 was recovered (more than 95% wt) in the water phase.…”

Section: Deprotection Of Borane Complexesmentioning

confidence: 99%

Phosphane and Bis(phosphane) Ligands from Phosphinic Acids

et al. 2000

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The Boyd−Regan methodology allowed for access to various cyclic or benzylic mono‐ and bis(phosphinic acids) 1−6. The reduction of monophosphinic acids to secondary phosphanes 7−9 was achieved with silanes. On the other hand, reduction of the bis(phosphinic acids) with LiAlH4 led to bis(phosphanes) 12−13. Various cyclic phosphanes and bis(phosphanes) were obtained by the alkylation of these secondary phosphanes (as their borane adducts). The Michael addition of the same borane adducts to vinylic phosphonates led to phosphane−phosphonates which could be hydrolysed to new hydrosoluble phosphanes.

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“…[1] In many cases, hyperconjugation influences conformational equilibria, [2][3][4][5] modifies reactivity, [6][7][8] determines the selectivity of reactions, [9] and is enhanced dramatically in excited, radical, and ionic species. [10] Lone pairs of electrons on oxygen, nitrogen, sulfur, and other heteroatoms are particularly well-suited for the role of donor in hyperconjugative interactions and stereoelectronic effects, and their participation is well-documented in the scientific literature. Arguably, among these interactions, the most intensively studied effect is the anomeric effect.…”

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confidence: 99%

Study of the Substituent‐Influenced Anomeric Effect in the Ring‐Chain Tautomerism of 1‐Alkyl‐3‐aryl‐naphth[1,2‐e][1,3]oxazines

et al. 2006

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The stabilities of the trans (B) and cis (C) tautomeric ring forms that are experimentally observed in the ring‐chain tautomeric interconversion of 1‐alkyl‐3‐aryl‐2,3‐dihydro‐1H‐naphth[1,2‐e][1,3]oxazines has been investigated. Stability differences are explained by the analysis of the natural bond orbital results for the lone pairs of electrons that are on the heteroatoms in the oxazine ring system and by regression analysis of the calculated 13C NMR chemical shift values. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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Electrochemical oxidation of halomicin B to rifamycin S

Cited by 6 publications

References 5 publications

On Five- vs Six-membered Diacetal Formation from Threitol and the Intermediacy of Unusually Stable Protonated Species¹

On Five- vs Six-membered Diacetal Formation from Threitol and the Intermediacy of Unusually Stable Protonated Species¹

Phosphane and Bis(phosphane) Ligands from Phosphinic Acids

Study of the Substituent‐Influenced Anomeric Effect in the Ring‐Chain Tautomerism of 1‐Alkyl‐3‐aryl‐naphth[1,2‐e][1,3]oxazines

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Electrochemical oxidation of halomicin B to rifamycin S

Cited by 6 publications

References 5 publications

On Five- vs Six-membered Diacetal Formation from Threitol and the Intermediacy of Unusually Stable Protonated Species1

On Five- vs Six-membered Diacetal Formation from Threitol and the Intermediacy of Unusually Stable Protonated Species1

Phosphane and Bis(phosphane) Ligands from Phosphinic Acids

Study of the Substituent‐Influenced Anomeric Effect in the Ring‐Chain Tautomerism of 1‐Alkyl‐3‐aryl‐naphth[1,2‐e][1,3]oxazines

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On Five- vs Six-membered Diacetal Formation from Threitol and the Intermediacy of Unusually Stable Protonated Species¹

On Five- vs Six-membered Diacetal Formation from Threitol and the Intermediacy of Unusually Stable Protonated Species¹