Studies in perezone derivatives

Walls, F.; Padilla, Juan; Joseph‐Nathan, Pedro; Giral, Francisco; Escobar, Maya; Romo, J.

doi:10.1016/s0040-4020(01)82159-1

Cited by 47 publications

(24 citation statements)

References 11 publications

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“…A plausible route for the transformation of 18 into 21 would imply initial hydrolysis of the angelate ester at C-7 to leave a secondary hydroxy group that is at the beta position of the C-9 carbonyl group and therefore easily dehydrates to form the Δ 7 olefin of 22 . A second hydrolysis, now of the angelate at C-8, led to a Δ 7 -en-8-ol-9-one functional group distribution that tautomerizes to the Δ 9 -en-9-ol-8-one, thereby evidencing that the enolized form of the 8,9-α-diketone is more stable when the carbonyl group at C-9 is enolized, in agreement with a degradation product of α-pipitzol …”

Section: Resultsmentioning

confidence: 74%

“…A second hydrolysis, now of the angelate at C-8, led to a Δ 7 -en-8-ol-9-one functional group distribution that tautomerizes to the Δ 9 -en-9-ol-8-one, thereby evidencing that the enolized form of the 8,9-α-diketone is more stable when the carbonyl group at C-9 is enolized, in agreement with a degradation product of α-pipitzol. 19 Mechanistic Proposals. The reaction mechanisms for the formation of 8, 11, 14, 16, 18, and 22 (Schemes 1−3) were outlined according to the extensive knowledge of the transformation of terpenoids, which include site-specific deuterium labeling 20−29 to reinforce the existence of 1,2-and 1,3-hydride shifts.…”

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confidence: 99%

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Novel Sesquiterpene Skeletons by Multiple Wagner–Meerwein Rearrangements of a Longipinane-1,9-diol Derivative

et al. 2019

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The tricyclic sesquiterpene (1R,3R,4S,5S,7S,8S,9S,10R,11R)-7,8-diangeloyloxylongipinan-1,9-diol, or rasteviol (7), underwent multiple Wagner–Meerwein molecular rearrangements and several hydride shifts when treated with Et2O–BF3 to generate the six new compounds (1R,3R,4S,5R,7S,8S,9S,10R,11S)-7,8-diangeloyloxy-1,9-epoxyjiquilpane (8), (1R,3R,4S,5R,7R,8S,9S,11S)-8-angeloyloxy-1,7-epoxyzamor-10(14)-ene (11), (2S,3R,4R,5R,6R,7R,8S,9S,10S)-7,8-diangeloyloxy-6,9-epoxyjanitziane (14), (4R,5R,7S,8S,9S,10S,11S)-7,8-diangeloyloxy-9-hydroxyjiquilp-3(15)-ene (16), (2S,3S,5R,7S,8R,10S,11R)-7,8-diangeloyloxyiratzian-9-one (18), and (2S,3S,5R,10S,11R)-8-angeloyloxyiratzi-7-en-9-one (22), of which 8, 11, 14, and 18 possess new hydrocarbon skeletons. Their structures were determined by 1D and 2D NMR in combination with single-crystal X-ray diffraction analyses of derivatives 10, 15, 20, and 21, which allowed confirmation of their absolute configurations by means of the Flack and Hooft parameters. In addition, some reaction mechanism information was gained from deuterium labeling experiments.

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Section: Resultsmentioning

confidence: 74%

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confidence: 99%

Novel Sesquiterpene Skeletons by Multiple Wagner–Meerwein Rearrangements of a Longipinane-1,9-diol Derivative

et al. 2019

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“…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 α ‐pipitzol ( 4 ) and β ‐pipitzol ( 5 ) followed after extensive chemical degradation reactions, which allowed determining the structure of perezone ( 1 ), whereas their absolute configuration was established by optical rotatory dispersion measurements . In addition, a single crystal X‐ray diffraction study independently confirmed the structure of α ‐pipitzol ( 4 ) and related molecules .…”

Section: Introductionmentioning

confidence: 93%

NMR‐based conformational analysis of perezone and analogues

Zepeda

Burgueño‐Tapia

Pérez‐Hernández

et al. 2013

Magnetic Reson in Chemistry

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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.

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“…In the course of synthetic studies directed towards a-pipitzol (Walls, Padilla, Joseph-Nathan, Giral, Escobar & Romo, 1966) we obtained an intermediate (III) whose structure required elucidation. * Contribution No.…”

Section: (2) 1528 (2)olmentioning

confidence: 99%