A practical six-step synthesis of (S)-camptothecin

An asymmetric synthesis of (S)-camptothecin (1) has been accomplished in six steps starting from two commercially available heterocycles. [reaction: see text]

Model studies toward the total synthesis of the Lycopodium alkaloid spirolucidine

[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.

Synthesis and reactivity of N-acyl-5- (1-hydroxyalkyl)-2,3-dihydro-4-pyridones

[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.

Enantiopure 2,3-dihydro-4-pyridones as synthetic intermediates: a concise asymmetric synthesis of (+)-allopumiliotoxin 267A

[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.

Addition of metallo enolates to chiral 1-acylpyridinium salts: total synthesis of (+)-cannabisativine

[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.

Enantiopure N-acyldihydropyridones as synthetic intermediates: asymmetric synthesis of (-)-slaframine

[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.

The Mukaiyama-Michael reaction of N-acyl-2,3-dihydro-4-pyridones: regio- and stereoselective synthesis of cis-2,6-disubstituted 1,2,5,6-tetrahydropyridines

[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.

Enantiopure N-acyldihydropyridones as synthetic intermediates: asymmetric synthesis of benzomorphans

[formula: see text] Concise asymmetric syntheses of several benzomorphan derivatives have been accomplished using enantiopure 2,3-dihydro-4-pyridones as chiral building blocks.

IMDA/retro-Mannich approach to cis-perhydroquinoline Lycopodium alkaloids: asymmetric synthesis of (+)-luciduline

[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.

An unusual C-4a hydroxylated decahydroquinolone

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.

4-Methoxy-1-[(1R,4S,5R)-8-phenyl-menthoxycarbonyl]pyridinium hexachloroantimonate, C23H30NO3+.SbCl6-

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.

Analogs of camptothecin

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.