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).
Stereoselective synthesis and transformation of pinane-based 2-amino-1,3-diols
Bajtel, ákos,Raji, Mounir,Haukka, Matti,Fül?p, Ferenc,Szakonyi, Zsolt
, p. 983 - 990 (2021/05/11)
A library of pinane-based 2-amino-1,3-diols was synthesised in a stereoselective manner. Isopinocarveol prepared from (?)-α-pinene was converted into condensed oxazolidin-2-one in two steps by carbamate formation followed by a stereoselective aminohydroxylation process. The relative stereochemistry of the pinane-fused oxazolidin-2-one was determined by 2D NMR and X-ray spectroscopic techniques. The regioisomeric spiro-oxazolidin-2-one was prepared in a similar way starting from the commercially available (1R)-(?)-myrtenol (10). The reduction or alkaline hydrolysis of the oxazolidines, followed by reductive alkylation resulted in primary and secondary 2-amino-1,3-diols, which underwent a regioselective ring closure with formaldehyde or benzaldehyde delivering pinane-condensed oxazolidines. During the preparation of 2-phenyliminooxazolidine, an interesting ring-ring tautomerism was observed in CDCl3
Design of stable mixed-metal MIL-101(Cr/Fe) materials with enhanced catalytic activity for the Prins reaction
álvaro, Mercedes,García, Hermenegildo,Giménez-Marqués, Mónica,Gkaniatsou, Effrosyni,Greneche, Jean-Marc,Navalón, Sergio,Santiago-Portillo, Andrea,Serre, Christian,Sicard, Clémence,Steunou, Nathalie,Vallés-García, Cristina
supporting information, p. 17002 - 17011 (2020/09/16)
This work highlights the benefit of designing mixed-metal (Cr/Fe) MOFs for enhanced chemical stability and catalytic activity. A robust and stable mixed-metal MIL-101(Cr/Fe) was prepared through a HF-free direct hydrothermal route with Fe3+ content up to 21 wt%. The incorporation of Fe3+ cations in the crystal structure was confirmed by 57Fe M?ssbauer spectrometry. The catalytic performance of the mixed metal MIL-101(Cr/Fe) was evaluated in the Prins reaction. MIL-101(Cr/Fe) exhibited a higher catalytic activity compared to MIL-101(Cr), improved chemical stability compared to MIL-101(Fe) and a higher catalytic activity for bulky substrates compared to MIL-100(Fe). In situ infra-red spectroscopy study suggests that the incorporation of Fe3+ ions in MIL-101 structure leads to an increase in Lewis acid sites. It was thus concluded that the predominant role of Cr3+ ions was to maintain the crystal structure, while Fe3+ ions enhanced the catalytic activity.
“Dark” Singlet Oxygen Made Easy
Elsherbini, Mohamed,Allemann, Rudolf K.,Wirth, Thomas
, 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.
