Oxidative Rearrangement of Tertiary Allylic Alcohols Employing Oxoammonium Salts

Shibuya, Masabumi; Tomizawa, Masaki; Iwabuchi, Yoshiharu

doi:10.1021/jo800634r

Cited by 114 publications

(90 citation statements)

References 48 publications

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“…[85] Reactions occur via the adduct D, which is obtained by reaction of the tertiary alcohol with salt 10. Heterolysis of the C À O bond will lead to ion pair E, which then collapses to F. Intermediate F can eventually fragment to product 21 and the protonated hydroxylamine 11.…”

Section: Oxidation Of Alcoholsmentioning

confidence: 99%

Nitroxides: Applications in Synthesis and in Polymer Chemistry

2011

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This Review describes the application of nitroxides to synthesis and polymer chemistry. The synthesis and physical properties of nitroxides are discussed first. The largest section focuses on their application as stoichiometric and catalytic oxidants in organic synthesis. The oxidation of alcohols and carbanions, as well as oxidative C-C bond-forming reactions are presented along with other typical oxidative transformations. A section is also dedicated to the extensive use of nitroxides as trapping reagents for C-centered radicals in radical chemistry. Alkoxyamines derived from nitroxides are shown to be highly useful precursors of C-centered radicals in synthesis and also in polymer chemistry. The last section discusses the basics of nitroxide-mediated radical polymerization (NMP) and also highlights new developments in the synthesis of complex polymer architectures.

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Section: Oxidation Of Alcoholsmentioning

confidence: 99%

Nitroxides: Applications in Synthesis and in Polymer Chemistry

2011

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“…7 Unfortunately, all attempts to oxidatively rearrange allylic alcohol 3.12 to enone 3.13 were unsuccessful. The use of various Cr (VI) 8 reagents, hypervalent iodine reagents, 9 or Noxoammonium salts 10 was ineffective, and largely resulted in the recovery of starting material or decomposition. Attempts to isomerize the allylic alcohol without oxidation were also unsuccessful.…”

Section: And Ester Formationmentioning

confidence: 99%

“…In turn, 1.7 serves as the progenitor to many different alkaloid frameworks including the strychnos, mavacurine, and akuammiline varieties. 10 For example, the strychnos alkaloid preakuammicine (1.8) would arise from a cyclization between C2 and C16, whereas the mavacurine alkaloid pleiocarpamine (1.9) stems from a cyclization between N1 and C16. The akuammiline framework, on the other hand, derives from an intramolecular oxidative coupling between C7…”

Section: Introductionmentioning

confidence: 99%

“…The use of an alkene as an aldehyde mask presented a viable workaround, and led to the design of substrate 2.9. 10 After the Fischer indolization of 2.9 to furnish 2.11, the alkene would be oxidatively cleaved at a late stage to access the correct C5 aldehyde oxidation state found in the natural product. 8,11 Finally, the viability of the Fischer indolization reaction was a notable !…”

Section: Introductionmentioning

confidence: 99%

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Total Synthesis of (±)-Picrinine

2014

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Throughout history, organisms have ensured their survival by producing a wide variety of small molecule natural products. These entities commonly serve roles in cell function and signaling, and have also provided a defense system to combat infectious parasites. In the realm of synthetic chemistry, natural products serve as an architectural inspiration for the development of novel chemical transformations and molecular cascade processes. Ultimately, the synthesis of natural products that have biological importance holds promise toward the understanding of a plethora of biochemical pathways and the treatment of disease.iii This dissertation describes synthetic efforts toward the alkaloid picrinine. This molecule is a member of the akuammiline alkaloid class, and it bears a complex molecular scaffold unaddressed by synthetic chemistry. Central to the synthetic approach is the use of the Fischer indolization reaction as a platform for rapidly building molecular complexity and constructing the salient furanoindoline core of picrinine. The earlier part of this dissertation describes a firstgeneration approach to the synthesis of picrinine, while the ensuing chapter concerns a secondgeneration route, which resulted in its total synthesis. This dissertation's final section concerns the development of a unified and enantioselective approach to the akuammiline alkaloid family, in addition to a formal enantioselective synthesis of both aspidophylline A and picrinine. In summary, the synthetic endeavors described emphasize the importance natural products hold for the development of novel synthetic strategies and transformations.iv The dissertation of Joel Michael Smith is approved.

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“…[20][21][22][23][24][25][26] They exhibit extremely high activities toward a wide range of alcohols, including structurally hindered secondary alcohols that TEMPO fails to efficiently oxidize. 20,21) A structure-activity comparison indicated that the steric congestion near the active center exerts a critical impact on catalytic efficiency.…”

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confidence: 99%

9-Azanoradamantane N-Oxyl (Nor-AZADO): A Highly Active Organocatalyst for Alcohol Oxidation

et al. 2011

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A highly active organocatalyst for alcohol oxidation has been developed. 9-Azanoradamantane N-oxyl (Nor-AZADO 4), constituting an unhindered, stable nitroxyl radical, exhibits superior catalytic activity to 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and AZADOs in the oxidation of alcohols to their corresponding carbonyl compounds.Key words organocatalyst; nitroxyl radical; alcohol oxidation; aerobic oxidation; 2-azaadamantane N-oxyl AZADO The oxidation of alcohols to their corresponding carbonyl compounds is one of the most fundamental transformations in both laboratory synthesis and industrial manufacturing, and numerous methods of such oxidation have been developed.1,2) In recent years, a stable class of nitroxyl radicals, as exemplified by TEMPO [2,2,6,6-tetramethyl piperidinyl 1-oxyl (1); Fig. 1], has been extensively used as a catalyst for the oxidation of alcohols in a wide range of chemistry. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] In particular, TEMPO-catalyzed alcohol oxidation has high priority in the pharmaceutical industry as an efficient, mild, and environmentally acceptable method. However, TEMPO is often inefficient in the oxidation of structurally hindered alcohols, posing a problem in the oxidation of secondary alcohols.We have recently reported that a less-hindered class of nitroxyl radicals, namely, 2-azaadamantane N-oxyls [AZADOs; AZADO (2a) and 1-Me-AZADO (2b)] and 9-azabicyclo[3.3.1]nonane N-oxyl [ABNO (3)], exhibit significantly enhanced reactivity compared with TEMPO.20-26) They exhibit extremely high activities toward a wide range of alcohols, including structurally hindered secondary alcohols that TEMPO fails to efficiently oxidize. 20,21) A structure-activity comparison indicated that the steric congestion near the active center exerts a critical impact on catalytic efficiency. 20) In our continuous interest in nitroxyl-radical-based oxidation, we envisaged that the catalytic activity of nitroxyl radicals can further be enhanced by reducing the steric factors around their active center. We herein report the advanced catalytic activity of 9-azanoradamantane N-oxyl [Nor-AZADO (4); Fig. 1]. This new catalyst exhibits superior catalytic efficiency to AZADO, 1-Me-AZADO and ABNO as well as to TEMPO.Nor-AZADO (4) was firstly synthesized in 1978 by Dupeyre and Rassat and reported to be a stable class of nitroxyl radicals.27) To the best of our knowledge, however, no study of Nor-AZADO has been reported since then. We were particularly interested in determining whether Nor-AZADO, which is a constraint variant of AZADO, produces the oxoammonium ions, which are useful for alcohol oxidation.Nor-AZADO was prepared in five steps from acetonedicarboxylic acid (5), glutaraldehyde, and benzylamine, by a previous method (Chart 1) with slight modification.

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Oxidative Rearrangement of Tertiary Allylic Alcohols Employing Oxoammonium Salts

Cited by 114 publications

References 48 publications

Nitroxides: Applications in Synthesis and in Polymer Chemistry

Nitroxides: Applications in Synthesis and in Polymer Chemistry

Total Synthesis of (±)-Picrinine

9-Azanoradamantane N-Oxyl (Nor-AZADO): A Highly Active Organocatalyst for Alcohol Oxidation

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