15741-79-4Relevant articles and documents
An improved synthesis of canthin-6-one
Czerwinski, Kevin M.,Zificsak, Craig A.,Stevens, John,Oberbeck, Melissa,Randlett, Christopher,King, Melissa,Mennen, Steve
, p. 1225 - 1231 (2003)
An improved route has been devised which provides canthin-6-one in the highest yield from tryptamine to date. Tryptamine is converted to Nb-benzyltryptamine via reaction with benzoylchloride and reduction using LAH. Pictet-Spengler condensation with 2-ketoglutaric acid, removal of the protecting group by CTH, and aromatization with MnO2 affords canthin-6-one in 48% overall yield.
Sequential acid/base-catalyzed polycyclization of tryptamine derivatives. A rapid access to Buechi's ketone
Heureux, Nicolas,Wouters, Johan,Marko, Istvan E.
, p. 5245 - 5248 (2005)
(Chemical Equation Presented) The development of an efficient and diastereoselective methodology that allows the rapid construction of the tetracyclic core of the Aspidosperma and Strychnos alkaloid families is decribed. Our approach relies upon two key steps: a sequential silica gel/potassium tert-butoxide polycyclization of a tryptamine precursor and a tandem oxidative decarboxylation/ring-closing reaction. The assembly of Buechi's ketone, a key intermediate in the synthesis of vindorosine, has been accomplished using this approach.
A simple and efficient method for constructing azepino[4,5-b]indole derivatives via acid catalysis
Kumar Boominathan, Siva Senthil,Reddy, Mutra Mohana,Hou, Ruei-Jhih,Chen, Hui-Fen,Wang, Jeh-Jeng
, p. 1872 - 1875 (2017)
A new synthetic methodology has been developed to prepare the biologically important azepino[4,5-b]indole derivatives under Br?nsted acid catalysis. The notable features of this protocol include its operational simplicity, high reaction yields and environmentally benign and mild reaction conditions.
Synthesis of ajmalicine derivatives using Wittig-Horner and Knoevenagel reactions
Boumendjel, Ahcene,Nuzillard, Jean-Marc,Massiot, Georges
, p. 9033 - 9036 (1999)
2-(2,3,4,9-Tetrahydro-1H-β-carbolin-1-yl)acetaldehyde, synthesized from tryptamine in five steps, is easily homologated by Wittig-Horner or Knoevenagel reactions to substituted acrylates. These highly reactive compounds are key intermediates in the synthesis of analogs of the natural indol alkaloid ajmalicine.
Synthesis, in vitro antibacterial activities of a series of 3-N-substituted canthin-6-ones
Dai, Jiang-Kun,Dan, Wen-Jia,Li, Na,Du, Hong-Tao,Zhang, Ji-Wen,Wang, Jun-Ru
, p. 580 - 583 (2016)
An improved synthetic route of canthin-6-one was accomplished. To further enhance the antibacterial potency and improve water solubility, a series of 3-N-alkylated and 3-N-benzylated canthin-6-ones were designed and synthesized, and their in vitro antibacterial activities were evaluated. A clear structure-activity relationship with peak minimal inhibitory concentration (MIC) values of 0.98 (μg·mL-1) was investigated. Particularly, compounds 6i-r and 6t were found to be the most potent compounds with minimal inhibitory concentration (MIC) values lower than 1.95 (μg·mL-1) against Staphylococcus aureus.
Gold-Catalyzed Carboamination of Allenes by Tertiary Amines Proceeding with Benzylic Group Migration
Milcendeau, Pierre,Gandon, Vincent,Guinchard, Xavier
, p. 2893 - 2902 (2021)
Tertiary amines bearing a benzyl-type group (CH2Ar) undergo Au(I)-catalyzed intramolecular addition to allenes. A formal 1,3-transfer of the CH2Ar group takes place during the cyclization. As demonstrated by both experimental and DFT studies, these unprecedented intramolecular carboaminations involve two consecutive [3,3] rearrangements via a dearomatized intermediate. Because of the poor stability of the enamine products, protocols were developed to convert them in situ to more stable polycyclic chiral compounds. (Figure presented.).
Asymmetric Total Synthesis of (-)-Arborisidine and (-)-19-epi-Arborisidine Enabled by a Catalytic Enantioselective Pictet-Spengler Reaction
Andres, Rémi,Wang, Qian,Zhu, Jieping
, p. 14276 - 14285 (2020)
A five-step total synthesis of arborisidine, a caged pentacyclic monoterpene indole alkaloid, has been accomplished in both racemic and enantioselective manners. The synthesis features the following three key steps: (a) a regioselective Pictet-Spengler reaction of tryptamine with 2,3-pentanedione; (b) a chemo-and stereoselective intramolecular oxidative cyclization; and (c) a complexity-generating aza-Cope/Mannich cascade followed by in situ oxidation and epimerization. A chiral pyrenylpyrrolidino-squaramide catalyzed enantioselective Pictet-Spengler reaction between tryptamine and 2,3-pentanedione is subsequently uncovered, allowing us to develop a five-step asymmetric synthesis of (-)-Arborisidine, an enantiomer of the natural substance. Both (±)-19-epi-Arborisidine and (-)-19-epi-Arborisidine are also synthesized, which undergo epimerization at room temperature in the presence of aqueous 2 N KOH to (±)-Arborisidine and (-)-Arborisidine, respectively. The 19-epi-isomer is also partially epimerized to arborisidine upon preparative TLC purification (eluent: MeOH/CHCl3 saturated with NH3) and equilibrium studies indicate that arborisidine is thermodynamically more stable than its 19-epimer. In line with Kam's biosynthesis proposal and their purification protocol, we suspect that 19-epi-Arborisidine could also be a natural product.
BF3·Et2O as a metal-free catalyst for direct reductive amination of aldehydes with amines using formic acid as a reductant
Fan, Qing-Hua,Liu, Xintong,Luo, Zhenli,Pan, Yixiao,Xu, Lijin,Yang, Ji,Yao, Zhen,Zhang, Xin
supporting information, p. 5205 - 5211 (2021/07/29)
A versatile metal- and base-free direct reductive amination of aldehydes with amines using formic acid as a reductant under the catalysis of inexpensive BF3·Et2O has been developed. A wide range of primary and secondary amines and diversely substituted aldehydes are compatible with this transformation, allowing facile access to various secondary and tertiary amines in high yields with wide functional group tolerance. Moreover, the method is convenient for the late-stage functionalization of bioactive compounds and preparation of commercialized drug molecules and biologically relevant N-heterocycles. The procedure has the advantages of simple operation and workup and easy scale-up, and does not require dry conditions, an inert atmosphere or a water scavenger. Mechanistic studies reveal the involvement of imine activation by BF3and hydride transfer from formic acid.
Fe-Catalyzed Pictet-Spengler-Type Cyclization via Selective Four-Electron Reductive Functionalization of CO2
Li, Wen-Duo,Chen, Jie,Zhu, Dao-Yong,Xia, Ji-Bao
supporting information, p. 614 - 620 (2021/02/12)
Herein, we describe a novel catalytic Pictet-Spengler-type cyclization using CO2 as a nontoxic and sustainable C1 feedstock with environmentally benign and non-precious-metal iron as catalyst. The reaction is achieved by selective four-electron reduction of CO2 into methylene level intermediate through carefully tuning the reaction parameters. A variety of tetrahydro-β-carbolines and other nitrogen-containing heterocycles can be easily obtained under mild conditions. Mechanistic studies have shown that tetrahydro-β-carbolines are probably obtained via spiroindolenine intermediates.
Selective construction of alkaloid scaffolds by alcohol-based direct and mild aerobic oxidative Pictet-Spengler reactions
Han, Feng,Li, Huan,Liu, Haicheng,Liu, Jianping,Xu, Qing
supporting information, p. 7079 - 7085 (2020/10/02)
Employing TBN/TEMPO as the catalysts and oxygen as the oxidant, the biologically and pharmaceutically significant tetrahydro-β-carboline and β-carboline alkaloid scaffolds that used to be obtained by multi-step processes can now be selectively obtained in only one-stepviadirect aerobic oxidative Pictet-Spengler reactions of tryptamines with alcohols under mild conditions, with water generated as the byproduct. In this reaction, TBN/TEMPO was interestingly found to be able to facilitate the cyclization step of the whole reaction. This method tolerates a variety ofC- andN-substituted tryptamines, and both the more reactive benzylic and allylic alcohols and the less reactive aliphatic alcohols. This method can also be extended to dihydro-β-carboline synthesis and applied to the more available and more economical tryptophan for β-carboline synthesis, revealing its broad substrate scope and potential in synthetic applications.
