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Quinolizinium ring

A number of successful approaches to the indolo[2,3-a]quinolizinium ring system (252) (generally leading to reduced derivatives) have been reported by Swan and co-workers. By treating l-(4 -hydroxybutyl)-l,2,3,4-tetrahydro-j8-carboline (391) with hydrobromic acid followed by base, l,2,3,4-tetrahydro-12jEf-indolo[2,3- ]quinolizinium bromide... [Pg.178]

The parent skeleton of the alkaloids containing the indolo[2,3-n] quinolizinium ring system 321 was examined spectroscopically (Scheme 99). On conversion to the deprotonated form 322 in CD3OD, all resonance frequencies shift to higher field and this tendency is particularly... [Pg.148]

The quinolizinium ring can behave as the diene component in reverse electron demand Diels-Alder reactions. For example (Equation 1), the reaction between a dienophile generated in situ by acid-catalyzed dehydration of precursor 72 and quinolizinium 73 gave the l,4-ethanobenzo[A]quinolizinium derivative 74 <2001BML519>. [Pg.15]

A carboxymethyl group at position 4 of the quinolizinium ring undergoes decarboxylation in excellent yield (Scheme 42) (76JCS(P1)341). [Pg.541]

Although there has been no example of a quinone within the quinolizinium ring system, oxidation of suitable benzo[ ]quinoIizinium bromides with two hydroxyl groups on the fused ring has afforded quinones (Scheme 56) in good yields (70JHC91). [Pg.544]

The remaining reactions for the establishment of a bond adjacent to the pyridine nitrogen of a potential quinolizinium ring are presumed to involve the attack of the unshared pair of electrons of the nitrogen upon a carbon bearing a halogen atom. The most direct synthesis of this type might involve the cyclization of l-(2-pyridyl)-4-halobutadiene (130)... [Pg.553]

The quaternization of 2-pyridinecarbaldehyde with 2,3,6-trimethoxy-9-phenanthryl-methyl bromide (183) yielded a salt (184) which, when cyclized, afforded a dibenz[/i,/]acridizinium derivative (185). Reduction of the quinolizinium ring of (185) afforded ( )-cryptopleurine (57JA3287). [Pg.563]

B. Acidities of Hydroxy Group Combined with the Quinolizinium Ring. 347... [Pg.262]

Hydrogen bromide Ring closure of acetals with preferential O-debenzylation Quinolizinium ring... [Pg.231]


See other pages where Quinolizinium ring is mentioned: [Pg.527]    [Pg.543]    [Pg.545]    [Pg.294]    [Pg.312]    [Pg.310]    [Pg.527]    [Pg.543]    [Pg.545]    [Pg.282]    [Pg.347]    [Pg.351]    [Pg.312]    [Pg.29]    [Pg.399]    [Pg.328]    [Pg.617]    [Pg.213]    [Pg.284]    [Pg.444]   
See also in sourсe #XX -- [ Pg.21 ]




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