Zobrazeno 1 - 10
of 24
pro vyhledávání: '"Hans Fritz"'
Publikováno v:
Tetrahedron Letters. 33:4153-4156
The preparative potential of rac -tritwistatriene ( 2 ) as precursor for other novel (CH) 14 hydrocarbons is explored. Solution thermolysis generates the primarily desired pentaene 1 together with trienes 7 and 9 . From FVP experiments, 1 is obtained
Publikováno v:
Tetrahedron Letters. 33:619-622
Monounsaturated, highly pyramidalized, highly reactive (i.a. dienophilic, dipolarophilic) dodecahedranes ( 2,10 ) are prepared from an adequately functionalized bisseco substrate. Cheletropic (-N 2 O; -SO 2 ) and retro-DA reactions are probed as pote
Publikováno v:
Tetrahedron Letters. 27:1269-1272
In a conformationally rigid cage substrate (15), a clean imine/ene photo-[2+2]-cycloaddition was effected by direct or sensitized (acetone) excitation.
Publikováno v:
Tetrahedron Letters. 18:4385-4388
Publikováno v:
Tetrahedron Letters. 18:4199-4202
Publikováno v:
Tetrahedron Letters. 20:3847-3850
Tris-[2.2.1]- and tris-[2.2.2]-σ-homobenzenes are synthesised by reaction of 1,1′-bicyclobutenyl with appropriate dienophiles and hydrogenation of the adducts.
Publikováno v:
Tetrahedron Letters. 27:3135-3138
Reaction of [E,E]-hexa-2,4-dienal 2 with nitrosobenzene led regiospecifically to the Diels-Alder cycloadduct 4b which is unstable at room temperature. Its enol form 5b underwent a hetero-Cope rearrangement, giving ultimately the pyrroloindole 7b . Si
Publikováno v:
Tetrahedron Letters. 25:2459-2462
Upon direct (sensitised) excitation selective metathesis is observed for the azoxy/ene 4 (with no intermediate being detectable at −50°C), quantitative [2+2] addition for the azo/ene 2. Thermally 4 undergoes uniform cycloaddition (t1/2(18°C) ca.
Publikováno v:
Tetrahedron Letters. 28:5497-5500
Cis,cis-trialkyltriaziridine 4 was prepared via azo/nitrene addition; upon oxidation above −40°C no intermediate was detected on the way to the azo/nitroso-product 26 .
Publikováno v:
Tetrahedron Letters. 27:4003-4006
On thermal treatment of the aziridines 5a - f intramolecular cycloaddition reactions of the intermediate azomethine ylides 6 result in the formation of the metacyclophanes 7 - 9 . For 7a and 7b the conformational barriers areestimated to be approxima