- Stepwise preparation of all- cis 1,3,4-trifluoro-2-phenylcyclohexane, avoiding a phenonium intermediate
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The original synthesis of all-cis 1,2,4,5,-tetrafluoro-2-phenylcyclohexane resulted in a trifluorocyclohexene as a significant co-product of the final fluorination step. This product was notable in that an elimination reaction was accompanied by C-F bond formation that had occurred with a retention of configuration. In order to deconvolute this reaction, the two isomers of the ditriflate diol precursor were separated, and they were each treated independently with Et3N·3HF. One gave the original all-cis 1,2,4,5,-tetrafluoro-2-phenylcyclohexane and the other the trifluorocyclohexene. A deuterium labeling experiment was carried out, resulting in a distribution of the isotope in the trifluorocyclohexene consistent with an intermediate (symmetrical) phenonium intermediate. Cognisant of this, a controlled elimination reaction of one of the diastereoisomers with DBU, followed by hydrogenation, gave a cyclohexane triflate, which, on fluorination, gave the all-cis 1,2,3-trifluoro-2-phenylcyclohexane now with an inversion of configuration.
- Durie, Alastair J.,Fujiwara, Tomoya,Al-Maharik, Nawaf,Slawin, Alexandra M. Z.,O'Hagan, David
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- Method for reducing aromatic C-N/Cl C/I bond to aromatic-H / D
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A method of reducing C an aromatic-N C/Cl/I bond to an aromatic-H / D, the process being a stable aromatic quaternary ammonium salt. After addition of the base and the solvent, the aromatic compound or the deuterated aromatic compound can be efficiently prepared by irradiation with visible light or ultraviolet light. The method can efficiently convert stable aromatic-N/I chemical bonds into aromatic-H / D bonds by visible light or ultraviolet light in a cheap and easily available solvent or deuterated solvent without using a catalyst or a transition metal compound C C. The whole production process is green, environment-friendly, low in cost, wide in substrate applicability, high in yield, high in deuterated rate, simple and convenient to operate, free of explosion risk and remarkable in advantage compared with the conventional production process.
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Paragraph 0032
(2021/09/08)
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- Photoinduced catalyst-free deborylation-deuteration of arylboronic acids with D2O
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Herein, novel photoinduced catalyst-free deborylation-deuteration of arylboronic acids with D2O is reported. The protocol was compatible with a variety of functionalities, including halogen, alkoxy, cyano, sulfonyl, trimethylsilyl, trifluoromethoxy, alkyl, hydroxyl, free acid, amide, and heteroaromatic rings. A wide range of deuterated products were obtained in good yields with a high level of deuteration. This method provides a green and practical pathway to synthesize deuterium labelled compounds under mild conditions.
- Lang, Yatao,Li, Chao-Jun,Peng, Xiangjun,Zeng, Huiying
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supporting information
p. 6323 - 6327
(2020/11/09)
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- Selective halogen - Magnesium exchange reaction via organomagnesium ate complex
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Halogen-magnesium exchange of various aryl halides is achieved with a magnesium ate complex at low temperatures. Tributylmagnesate (nBu3MgLi) induces facile iodine-magnesium exchange at -78 °C. Dibutylisopropylmagnesate (iPrnBu2MgLi) is more reactive than nBu3MgLi, and this reagent accomplishes selective bromine-magnesium exchange at -78 °C. This procedure is utilized for the preparation of various polyfunctionalized arylmagnesium species. The exchange of alkenyl halides using this method proceeds with retention of configuration of the double bond.
- Inoue,Kitagawa,Shinokubo,Oshima
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p. 4333 - 4339
(2007/10/03)
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- Memory effects in Pd-catalysed allylic alkylation: Stereochemical labelling through isotopic desymmetrization
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2H-Labelled and 18O-labelled cyclopentenyl esters (±)-4 and (±)-5 are used as probes for memory effects in Pd-catalysed allylic alkylation. 2H-Labelled alkylation product 6 arising from stereospecific Pd-catalysed reaction
- Lloyd-Jones, Guy C.,Stephen, Susanna C.
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p. 2539 - 2549
(2007/10/03)
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