The reaction mechanism of the perezonepipitzol transformation

Joseph‐Nathan, Pedro; Mendoza, V.; García, E.

doi:10.1016/0040-4020(77)80163-4

Cited by 39 publications

(34 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[8,9] The later reaction path was confirmed when the reaction was carried out using 15-deuteroperezone to afford a-pipitzol (4) and b-pipitzol (5) labeled at only one methyl of the gem-dimethyl group of each compound. [3] Under the thermal reaction condition, no chiral induction by the sole stereogenic center of perezone (1) was evident. In turn, the structures of tricyclic natural occurring sesquiterpenes a-pipitzol (4) and b-pipitzol (5) followed after extensive chemical degradation reactions, [10] which allowed determining the structure [11] of perezone (1), whereas their absolute configuration was established by optical rotatory dispersion measurements.…”

Section: Introductionmentioning

confidence: 97%

“…Such structural diversity of perezone derivatives is closely related to both the chemical nature and the relative conformation of the side chain and the quinone ring. For instance, thermal transformation of perezone ( 1 ) affords a 1 : 1 mixture (Figure ) of α ‐pipitzol ( 4 ) and β ‐pipitzol ( 5 ), whereas in the presence of F 3 B/OEt 2 , it yields a 9 : 1 mixture in favor of the α ‐isomer. This stereoselectivity was inverted to a 1 : 3 mixture in favor of the β ‐isomer by treating methyl ether 2 with AlCl 3 /Et 2 S and further improved to a 1 : 8 ratio by treating 2 with F 3 B/OEt 2 .…”

Section: Introductionmentioning

confidence: 99%

“…From a mechanistic point of view, the thermal transformation of perezone ( 1 ) to α ‐pipitzol ( 4 ) and β ‐pipitzol ( 5 ) was either proposed as a two‐step Michael‐type intramolecular cycloaddition or rationalized by Woodward as a concerted cycloaddition involving a [1,9]‐sigmatropic change of order . The later reaction path was confirmed when the reaction was carried out using 15‐deuteroperezone to afford α ‐pipitzol ( 4 ) and β ‐pipitzol ( 5 ) labeled at only one methyl of the gem ‐dimethyl group of each compound . Under the thermal reaction condition, no chiral induction by the sole stereogenic center of perezone ( 1 ) was evident.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

NMR‐based conformational analysis of perezone and analogues

Zepeda

Burgueño‐Tapia

Pérez‐Hernández

et al. 2013

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

Complete assignment of the (1)H NMR chemical shift and coupling constant values of perezone (1), O-methylperezone (2) and 6-hydroxyperezone (3) was carried out by total-line-shape-fitting calculations using the PERCH iterative spectra analysis software (PERCH Solutions Ltd., Kuopio, Finland). The resulting simulated spectra for the three compounds showed strong similarity to their corresponding experimental spectra. Particularly, all vicinal, allylic and homoallylic coupling constant values for the side chain of the three compounds were very similar, thus revealing that the conformation of these three molecules in solution is indeed almost identical. This fact is in agreement with extended side chain conformations over folded chain conformations because 1, 2 and 3 undergo completely different intramolecular cycloaddition reactions. In addition, results of double pulsed field gradient spin echo NOESY 1D experiments performed on perezone (1) were unable to provide evidence for folded conformers.

show abstract

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

NMR‐based conformational analysis of perezone and analogues

Zepeda

Burgueño‐Tapia

Pérez‐Hernández

et al. 2013

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

show abstract

“…In addition, further asatonetype neolignans, heterotropanone-type compounds, and arylpropanoids were also synthesized under these conditions. 122 Based on a report by Joseph-Nathan, who first reported a [5+2]-cycloaddition 123 and later established a concerted mechanism, 124 olefin-functionalized phenols were also electrochemically cyclized in a related fashion by the Yamamura group to gain access to complex fused-ring natural products. 125,126 Anodic oxidation of phenol 53, which was prepared from 3,4-dimethoxyphenol (52), generated tricyclic intermediate 54 as a diastereomeric mixture in 80% yield.…”

Section: Short Review Synthesismentioning

confidence: 99%

Anodic Oxidation as an Enabling Tool for the Synthesis of Natural Products

Geske

Sato²,

Opatz³

2020

Synthesis

View full text Add to dashboard Cite

Electrochemistry provides a valuable toolbox for organic synthesis and offers an appealing, environmentally benign alternative to the use of stoichiometric quantities of chemical oxidants or reductants. Its potential to control current efficiency along with providing alternative reaction conditions in a classical sense makes electrochemistry a suitable method for large-scale industrial transformations as well as for laboratory applications in the synthesis of complex molecular architectures. Even though research in this field has intensified over the recent decades, many synthetic chemists still hesitate to add electroorganic reactions to their standard repertoire, and hence, the full potential of preparative organic electrochemistry has not yet been unleashed. This short review highlights the versatility of anodic transformations by summarizing their application in natural product synthesis.1 Introduction2 Shono-Type Oxidation3 C–N/N–N Bond Formation4 Aryl–Alkene/Aryl–Aryl Coupling5 Cycloadditions Triggered by Oxidation of Electron-Rich Arenes6 Spirocycles7 Miscellaneous Transformations8 Future Prospects

show abstract

“…of α and β pipitzols. 5 Since an unequivocal structural assignment of α-isopipitzol ( Fig. 1) has not been achieved, in this paper, we describe its structure confirmation based on a X-ray diffraction study.…”

mentioning

confidence: 96%