- Silylcyclopropanes by Selective [1,4]-Wittig Rearrangement of 4-Silyl-5,6-dihydropyrans
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4-Silyl-5,6-dihydropyrans undergo remarkably selective [1,4]-Wittig rearrangements to give silylcyclopropanes in good yields. The selectivity is independent of the silyl group, but it is influenced by the electronic character of the migrating center. Elec
- Mori-Quiroz, Luis M.,Maloba, Emmanuel W.,Maleczka, Robert E.
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supporting information
p. 5724 - 5728
(2021/07/31)
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- Pyridine radicals in synthesis. Part 3: Cyclopentannulation of pyridine via the 3-pyridyl radical and a formal synthesis of (±)-oxerine
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The allylation and propargylation of 3-bromo-4-formylpyridine under zinc-mediated Barbier conditions is described. The homoallylic alcohols produced are cyclised via the derived 3-pyridyl radical to give cyclopentannulated pyridines. One of these bicyclic compounds is converted into an advanced intermediate in a previous synthesis of the monoterpene alkaloid (±)-oxerine. (C) 2000 Elsevier Science Ltd.
- Jones, Keith,Fiumana, Andrea,Escudero-Hernandez, Maria L.
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p. 397 - 406
(2007/10/03)
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- Synthesis of allenyl ketones and their palladium-catalyzed cycloisomerization/dimerization: Approaching the limits
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The preparation of several new allenyl ketones 1a-j and 1o-q is reported. In the case of allenyl ketones with nucleophilic groups in the side-chain like 1k-m, the material polymerized during the purification procedure; with the dialkyl thioether In the product of a Pummerer isomerization, the acetoxymethyl alkyl thioether, 11 was formed. Depending on the route to 1 sometimes either the acetate adducts 8 and the 1-propynyl ketones 9 or the dipropargyl and propargyl allenyl carbinol 14 and 15 were observed as side-products. Good yields of the sensitive aryl γ-halogen-allenyl ketones 23a and 23b were obtained by a new synthetic route, on the other hand the aryl γ-silylallenyl ketone 23c was readily desilylated. Subjecting the new allenyl ketones to the PdCl2(MeCN)2 catalyst provided the 2-substituted furans 2 and the 2,4-disubstituted furans 3 in most cases. The yields and ratios of these products strongly depended on the nature of the groups being present. With the aryl thioether and the γ-halogen allenyl ketones the palladium-catalyzed reaction failed. Detailed structural information about the new products was provided by the X-ray structure analyses of the p-acetamidophenyl propargyl carbinol 6g and the 2-aryl-4-(1-methyl-3-aryl-3-oxo-propen-1-yl furan 3h. Wiley-VCH Verlag GmbH, 1999.
- Hashmi, A. Stephen K.,Choi, Ji-Hyun,Bats, Jan W.
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p. 342 - 357
(2007/10/03)
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- Pyridine radicals in synthesis: A formal total synthesis of (±)-oxerine
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The cyclisation of pyridine radicals derived from 3-bromo-4-substituted pyridines carrying both alkene and alkyne groups in the 4-substituent to give is described. The cyclopentano[c]pyridine skeleton formed by cyclisation is found in many monoterpene alkaloids and a short synthesis of a late intermediate in the previous synthesis of (±)-oxerine is presented.
- Jones, Keith,Fiumana, Andrea
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p. 8049 - 8052
(2007/10/03)
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