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Inner-Outer-Ring Dienes

Inner-outer-ring dienes are very useful in the synthesis of polycyclic molecules. Their reactivity in the Diels-Alder reaction depends on the type of ring (carbo-cyclic, heterocyclic, aromatic) that bears the ethenyl group or on the electronic effects of substituents at the diene moiety [30]. [Pg.49]

Arylethenes are inner-outer-ring dienes in which the vinyl group is linked to an aromatic system. These dienes are poorly or moderately reactive the presence of electron-donating substituents in the diene moiety markedly increases their reactivity. Their cycloadditions are usually accelerated in order to be carried out under mild conditions. 1-Vinylnaphthalene is more reactive than 2-vinyl-naphthalene and styrenes. [Pg.219]

Heterocyclic derivatives as inner-outer ring dienes... [Pg.422]

Starting from some of the above 1-hydroxycarbacephams 54, the synthesis of inner-outer-ring 2-[/< r/-butyldimethylsilyloxy dienes 55 with a carbacepham structure and their totally 7t-facial endo selective Diels-Alder reactions to structurally novel polycyclic p-lactams 56 have been reported (Scheme 19) [64]. [Pg.13]

A more versatile approach uses an inner-outer ring diene system such as compound 496, which reacted with iV-methylmaleimide in toluene at 145 °C in a sealed tube to give cycloadduct 497 in 91% yield <2004TL7255>. Similar procedures with different electrophiles have been reported by other workers who were able to combine consecutively the preparation of the inner-outer diene by RCM reaction (see Section 2.04.9.3) and the Diels-Alder reaction in a one-pot process, which gave increased yields in most cases for the polycyclic compounds when compared with the two-pot approach <2004S2665>. [Pg.305]

Inner-outer-ring dienes 104 are particularly useful for the synthesis of polycyclic structures, because they enable the incorporation of additional rings into the sixmembered ring formed by the DA reaction (Scheme 10.106) [289]. Highly electron-deficient alkenes and alkynes react smoothly with 104 at room temperature. Benzaldehyde and N-benzyhdeneaniline can also be used as dienophiles in the presence of a catalytic amount of ZnCl2. Overall, the Diels-Alder reactivity of 104 is comparable with that of 102. [Pg.482]

Splitting of inner ring around the meri-dien. Equatorial outer ring splitting. Optically un ia-xial. [Pg.81]

Dienes can be open-chain, inner-ring (e.g., 80), outer-ring856 (e.g., 81), across rings (e.g., 82). or inner-outer (e.g., 83), except that they may not be frozen into a transoid conformation... [Pg.840]

Splitting of inner ring aifound meri-dien. Outer ring splitting into equatorial doublet. [Pg.81]

In order for the stereochemistry of the diene substituents to be maintained in 46 and 48, the relative motions of these substituents during ring formation must be as shown in 51. The outer substituents on the diene move toward each other, and the inner substituents move away from each other producing 52. Such motion is described as conrotatory (orbital motion in the same direction 51 52). Alternatively, the motion... [Pg.935]


See other pages where Inner-Outer-Ring Dienes is mentioned: [Pg.49]    [Pg.219]    [Pg.220]    [Pg.222]    [Pg.10]    [Pg.153]    [Pg.265]    [Pg.49]    [Pg.219]    [Pg.220]    [Pg.222]    [Pg.208]    [Pg.210]    [Pg.10]    [Pg.265]    [Pg.1063]    [Pg.358]    [Pg.1196]    [Pg.1197]    [Pg.358]    [Pg.358]    [Pg.352]    [Pg.573]    [Pg.125]    [Pg.573]   
See also in sourсe #XX -- [ Pg.49 , Pg.50 , Pg.51 , Pg.52 , Pg.53 , Pg.54 , Pg.55 , Pg.56 , Pg.57 , Pg.58 , Pg.59 , Pg.60 , Pg.61 , Pg.62 , Pg.63 , Pg.219 , Pg.220 , Pg.221 , Pg.222 ]




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Dienes inner-ring

Dienes outer-ring

Heterocycles derivatives as inner-outer ring dienes

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