RESUMO
[reaction: see text] A strategy for the synthesis of the spirocyclic core of spirolucidine was explored through a model study. The diene 4a was prepared and photolyzed to give the desired [2 + 2] photoadduct 17 containing the correct relative stereochemistry corresponding to spirolucidine.
Assuntos
Alcaloides/síntese química , Compostos de Espiro/síntese química , Lycopodiaceae/química , Fotoquímica , Piridonas/químicaRESUMO
[figure: see text] A concise asymmetric synthesis of (+)-allopumillotoxin 267A has been accomplished using an enantiopure dihydropyridone building block. The synthesis is highly stereoselective and requires 10 steps from readily available material.
Assuntos
Alcaloides/síntese química , Indolizinas , Piperidinas , Piridonas/química , Animais , Anuros , EstereoisomerismoRESUMO
[structure: see text]. The Nozaki-Hiyama-Kishi reaction was used to prepare the 5-(1-hydroxyalkyl)-2,3-dihydro-4-pyridones 3. Reduction, oxidation, and substitution reactions of 3 were examined.
Assuntos
Piridonas/síntese química , Catálise , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , OxirreduçãoRESUMO
An asymmetric synthesis of (S)-camptothecin (1) has been accomplished in six steps starting from two commercially available heterocycles. [reaction: see text]
Assuntos
Antineoplásicos Fitogênicos/síntese química , Camptotecina/síntese química , Antineoplásicos Fitogênicos/química , Camptotecina/química , Compostos Heterocíclicos/químicaRESUMO
[formula: see text] A novel route to the first asymmetric synthesis of (+)-cannabisativine (1) is described. The total synthesis of 1 was accomplished with a high degree of regio- and stereoselectivity in 19 steps and 9% overall yield.
Assuntos
Canabinoides/síntese química , Canabinoides/química , Compostos Organometálicos , Compostos de Piridínio , EstereoisomerismoRESUMO
[formula: see text] An asymmetric synthesis of (-)-slaframine and N-acetylslaframine has been accomplished starting from an enantiopure dihydropyridone building block. The oxygen-carbon bond at C-1 was incorporated with complete stereoselectivity by using an efficient phenylselenocyclocarbamation reaction.
Assuntos
Alcaloides/síntese química , Micotoxinas/síntese química , Piridonas/síntese química , Rhizoctonia/química , EstereoisomerismoRESUMO
[formula: see text] The first chiral auxiliary mediated asymmetric synthesis of the naturally occurring Lycopodium alkaloid (+)-luciduline has been accomplished. Key steps include an IMDA reaction of a chiral dihydropyridine, a subsequent retro-Mannich ring opening, and a novel cationic reductive cyclization reaction.
Assuntos
Plantas Medicinais/química , Quinolinas/síntese química , Bases de Mannich , EstereoisomerismoRESUMO
[formula: see text] Concise asymmetric syntheses of several benzomorphan derivatives have been accomplished using enantiopure 2,3-dihydro-4-pyridones as chiral building blocks.
Assuntos
Benzomorfanos/síntese química , Piridonas/química , Benzomorfanos/química , EstereoisomerismoRESUMO
[formula: see text] A convenient regio- and stereoselective preparation of 1,2,5,6-tetrahydropyridines of the type 1 has been developed, starting from readily available N-acyl-2,3-dihydro-4-pyridones 2.
Assuntos
Piridinas/síntese química , Piridonas/química , Piridinas/química , EstereoisomerismoRESUMO
The crystal structure and the relative stereochemistry of the four asymmetric centers of an unusual C-4a hydroxylated decahydroquinolone, phenyl 1,2 alpha,3,4,-4a alpha,5 beta,6,7,8,8a alpha-decahydro-4a-hydroxy-4-oxo-2-propyl-5-vinylquinoline-1 -carboxylate, C21H27NO4, are reported. The H and OH groups at the ring juncture are cis to each other as are the two H atoms alpha to the N atom. The vinyl and OH groups are also cis to each other. The N atom is sp2 hybridized.
Assuntos
Quinolonas/química , Cristalização , Cristalografia por Raios X , Estrutura MolecularRESUMO
The 4-methoxypyridinium and oxycarbonyl moieties are coplanar and approximately parallel to the phenyl ring. The latter is involved in a number of short intramolecular interactions with the pyridinium and the oxycarbonyl atoms. Crystal packing is characterized by the presence of hydrophobic and hydrophilic channels, the former consisting of phenylmenthyl groups and the latter of pyridinium and SbCl6- ions.
Assuntos
Compostos Organometálicos/química , Compostos de Piridínio/química , Cristalografia por Raios X , Estrutura MolecularRESUMO
Several compounds having portions of the camptothecin ring system were prepared. These compounds were screened against L1210 lymphoid leukemia with negative results. Two of the analogs which contained the pyridine and hydroxylactone D and E rings were also screened for inhibition of DNA and RNA syntheses in HeLa cells. Each of these analogs had decreased activity as compared with comptothecin and there was no degradation of DNA in the HeLa cells. This suggest that the D and E rings are not a sufficient requirement for camptothecin-like activity.