19894-98-5Relevant articles and documents
Synthesis and ?-Facially Selective Cycloadditions of Pinofurans
Koever, A.,Hoffmann, H.M.R.
, p. 6831 - 6840 (1988)
The synthesis of the strained pinofuran (1) and methylpinofuran (2) was investigated by a number of approaches.The preferred route to 1 was via the monoprotected (Z)-enediol 8, which was obtained by Z-selective LiNEt2-induced opening of the epoxide derived from protected homoallylic alcohol 3 (nopol).Methylpinofuran (2) was prepared from 1,4-diketone 14, which was obtained by a vinyl-Grignard 1,4-addition to pinocarvone (12) followed by ozonolysis.Pinofurans 1 and 2 entered into Diels-Alder additions with dimethyl acetyenedicarboxylate, giving 15 and 16, respectively.Pinofuran (1) also reacted with allyl cations, giving cycloadducts 19 and 20.All cycloadditions were ?-facially selective, attack occurring exclusively from the face anti to the gem-dimethyl grouping.Further, in the case of cycloadduct 19, extended attack was slightly preferred over compact attack (19ββ : 19αα = 3:2) (α, β refer to the tetrahydropyranone moiety).
Selective C-H Allylic Oxygenation of Cycloalkenes and Terpenoids Photosensitized by [Cu(Xantphos)(neoc)]BF4
Kallitsakis, Michael G.,Gioftsidou, Dimitra K.,Tzani, Marina A.,Angaridis, Panagiotis A.,Terzidis, Michael A.,Lykakis, Ioannis N.
, p. 13503 - 13513 (2021/09/13)
We present herein for the first time the use of the [Cu(Xantphos)(neoc)]BF4 as a photocatalyst for the selective C-H allylic oxygenation of cycloalkenes into the corresponding allylic hydroperoxides or alcohols in the presence of molecular oxygen. The proposed methodology affords the products at good yields and has also been applied successfully to several bioactive terpenoids, such as geraniol, linalool, β-citronellol, and phytol. A mechanistic study involving also kinetic isotope effects (KIEs) supports the proposed singlet oxygen-mediated reaction. On the basis of the high chemoselectivity and yields and the fast and clean reaction processes observed, the present catalytic system, [Cu(Xantphos)(neoc)]BF4, has also been applied to the synthesis, at a laboratory scale, of the cis-Rose oxide, a well-known perfumery ingredient used in rose and geranium perfumes.
Selective Allylic Oxidation of Terpenic Olefins Using Co-Ag Supported on SiO2 as a Novel, Efficient, and Recyclable Catalyst
Aberkouks, Abderrazak,Mekkaoui, Ayoub Abdelkader,Ait Ali, Mustapha,El Firdoussi, Larbi,El Houssame, Soufiane
, (2020/02/15)
Co-Ag supported on the SiO2 catalyst was synthesized by the sol-gel method and characterized using XRD, FT-IR, TG-DTG, BET, CV, and SEM/EDX analysis. The catalytic performance of the resulting catalyst was examined by the oxidation of mono and sesquiterpenic olefins using hydrogen peroxide and tert-butyl peroxide as oxidant agents. Various parameters such as catalyst amount, temperature, and solvents have been studied. The Co-Ag supported on the SiO2 catalyst showed a high activity, selectivity, and recyclability for the selected oxidation reaction.
“Dark” Singlet Oxygen Made Easy
Elsherbini, Mohamed,Allemann, Rudolf K.,Wirth, Thomas
supporting information, p. 12486 - 12490 (2019/08/26)
An operationally simple continuous flow generator of “dark” singlet oxygen has been developed. The singlet oxygen was efficiently reacted with several chemical traps to give the corresponding oxygenated products in high yields. The developed “dark” singlet oxygen generator has been successfully applied in the synthesis of the antimalarial drug artemisinin.
