25921-22-6Relevant academic research and scientific papers
The Pauson-Khand reaction as a new entry to the synthesis of bridged bicyclic heterocycles: application to the enantioselective total?synthesis of (-)-alstonerine
Miller, Kenneth A.,Shanahan, Charles S.,Martin, Stephen F.
, p. 6884 - 6900 (2008/09/21)
The first application of the Pauson-Khand reaction (PKR) to the synthesis of azabridged bicyclic structures is described. Compounds containing azabicyclo[3.3.1]nonane and azabicyclo[3.2.1]octane rings fused to cyclopentenones were efficiently constructed
Concise, enantioselective total synthesis of (-)-alstonerine
Miller, Kenneth A.,Martin, Stephen F.
, p. 1113 - 1116 (2007/10/03)
(Chemical Equation Presented) A novel enantioselective total synthesis of (-)-alstonerine has been completed that requires only 15 steps from L-tryptophan. The synthesis features the first application of a Pauson-Khand reaction to synthesize an azabridged
An improved total synthesis of (+)-macroline and alstonerine as well as the formal total synthesis of (-)-talcarpine and (-)-anhydromacrosalhine-methine
Liao, Xuebin,Zhou, Hao,Yu, Jianming,Cook, James M.
, p. 8884 - 8890 (2007/10/03)
An intramolecular Pd-catalyzed α-vinylation process is described. This cyclization has been employed for the enantiospecific total synthesis of gram quantities of both (+)-macroline 3 and the macroline equivalent 4. This sequence is compared to the enolate-driven cross-coupling process. The intermediate 4 was also converted into (-)-alstonerine 1 via modification of an intramolecular Tsuji-Wacker oxidation. This sequence resulted in an improved total synthesis of (-)-talcarpine 5 and (-)-anhydromacrosalhinemethine 6 as well.
The first regiospecific, enantiospecific total synthesis of 6-oxoalstophylline and an improved total synthesis of alstonerine and alstophylline as well as the bisindole alkaloid macralstonine
Liao, Xuebin,Zhou, Hao,Wearing, Xiangyu Z.,Ma, Jun,Cook, James M.
, p. 3501 - 3504 (2007/10/03)
(Chemical Equation Presented) A Wacker sequence has been modified to rapidly generate ring E of (-)-alstonerine, (+)-6-oxoalstophylline, and (-)-alstophylline via a domino process. This one-pot sequence provides facile entry into the dihydropyranyl enone unit of many Alstonia alkaloids.
Enantiospecific Total Synthesis of the Sarpagine Related Indole Alkaloids Talpinine and Talcarpine as Well as the Improved Total Synthesis of Alstonerine and Anhydromacrosalhine-methine via the Asymmetric Pictet-Spengler Reaction
Yu, Peng,Wang, Tao,Li, Jin,Cook, James M.
, p. 3173 - 3191 (2007/10/03)
The enantiospecific total synthesis of talpinine 1 and talcarpine 2 has been accomplished from D-(+)-tryptophan in 13 steps (11 reaction vessels) in 10% and 9.5% overall yields, respectively. Moreover, this synthetic approach has been employed for the improved synthesis of alstonerine 3 and anhydromacrosalhine-methine 4 in 12% and 14% overall yield, respectively. A convenient synthetic route for the enantiospecific, stereospecific preparation of the key intermediate (-)-Na-H, Nb-benzyl tetracyclic ketone 15a via the asymmetric Pictet-Spengler reaction on a multihundredgram scale has been developed. A diastereocontrolled (>30:1) anionic oxy-Cope rearrangement and the intramolecular rearrangement to form ring-E and an Nb-benzyl/Nb-methyl transfer reaction also served as key steps. This general approach can now be utilized for the synthesis of macroline/ sarpagine related indole alkaloids and their antipodes for biological screening.
General approach for the synthesis of macroline/sarpagine related indole alkaloids via the asymmetric Pictet-Spengler reaction: The enantiospecific synthesis of (-)-anhydromacrosalhine-methine
Gan, Tong,Cook, James M.
, p. 5033 - 5036 (2007/10/03)
An enantiospecific total synthesis of (-)-anhydromacrosalhine-methine 3a has been accomplished from D-(+)-tryptophan via the asymmetric Pictet- Spengler reaction. A partial synthesis of 3a from the natural product (+)- ajmaline has also been completed.
Enantiospecific synthesis of (-)-alstonerine and (+)-macroline as well as a partial synthesis of (+)-villalstonine
Bi, Yingzhi,Zhang, Lin-Hua,Hamaker, Linda K.,Cook, James M.
, p. 9027 - 9041 (2007/10/02)
The enantiospecific synthesis of (-)-alstonerine (5) and (+)-macroline (8), as well as a partial synthesis of the Alstonia bisindole alkaloid villalstonine (2) has been completed. In addition, a more stable macroline equivalent 9 was prepared. The stereochemistry at C(15) and C(16) in 5 and 8 has been successfully installed by a stereoselective Claisen rearrangement followed by stereospecific hydroboration-oxidation of the exocyclic methylene function at C-16. The E ring in alstonerine 5 was constructed by a regioselective cyclization followed by a novel Swern oxidation under modified conditions [(COCl)2/DMSO/CH2Cl2, -78°C to -10°C/1.5 h; Et3N], whereas the C(20)-C(21) enone system in macroline (8) was generated via a convenient one pot process from the β-diol 45. Condensation of either synthetic (+)-macroline (8) or the macroline equivalent 9 with natural pleiocarpamine 7 in 0.2 N HCl furnished the antiamoebic, antimalarial bisindole alkaloid villalstonine 2. This constitutes the first partial synthesis of any of the Alstonia bisindoles from a synthetically derived indole moiety.
An efficient synthetic pathway to the macroline-type indole alkaloids, talcarpine and alstonerine from ajmaline
Takayama, Hiromitsu,Phisalaphong, Chada,Kitajima, Mariko,Aimi, Norio,Sakai, Shin-Ichiro
, p. 1383 - 1392 (2007/10/09)
Ajmaline (6) was transformed into two macroline-related indole alkaloids, talcarpine (1) and alstonerine (2) via the common synthetic intermediate (13). The stereochemistry at C19 position in talcarpine (1) and talpinine (5) were elucidated by NOE experim
