156424-91-8Relevant academic research and scientific papers
Rhodium(III)-catalyzed intramolecular annulation through C-H activation: Total synthesis of (±)-antofine, (±)-septicine, (±)-tylophorine, and rosettacin
Xu, Xianxiu,Liu, Yu,Park, Cheol-Min
, p. 9372 - 9376 (2012)
Annulation: The efficient synthesis of 3-hydroxyalkyl isoquinolones and 6-hydroxyalkyl 2-pyridones is enabled through the intramolecular annulation of alkyne-tethered hydroxamic esters (see scheme, Cp= pentamethylcyclopentadienyl). The reaction features high regioselectivity, broad substrate scope, and excellent functional-group tolerance, proceeds under mild reaction conditions with low catalyst loading, and obviates the need for an external oxidant.
A Gold(I)-Catalyzed Hydroamination/Cycloisomerization Cascade: Concise Synthesis of (±)-seco-Antofine and (±)-Septicine
Tian, Guilong,Song, Liangliang,Li, Zhenghua,Robeyns, Koen,Van Meervelt, Luc,Van Der Eycken, Erik V.
, p. 8441 - 8445 (2020/11/03)
A concise and flexible procedure for the synthesis of highly functionalized N-heterocyclic 1,6-annulated 2-pyridones and 2,3-annulated 4-pyrimidinones has been elaborated through a gold-catalyzed tandem hydroamination/cycloisomerization cascade. This novel and highly efficient method allows the rapid construction of these diverse N-heterocyclic scaffolds starting from readily available building blocks, and shows a wide scope and good functional group tolerance. The total synthesis of (±)-seco-antofine and (±)-septicine were realized employing this strategy.
A General Cp*CoIII-Catalyzed Intramolecular C?H Activation Approach for the Efficient Total Syntheses of Aromathecin, Protoberberine, and Tylophora Alkaloids
Lerchen, Andreas,Knecht, Tobias,Koy, Maximilian,Daniliuc, Constantin G.,Glorius, Frank
supporting information, p. 12149 - 12152 (2017/09/13)
Herein, we report a Cp*CoIII-catalyzed C?H activation approach as the key step to create highly valuable isoquinolones and pyridones as building blocks that can readily be applied in the total syntheses of a variety of aromathecin, protoberberine, and tylophora alkaloids. This particular C?H activation/annulation reaction was achieved with several terminal as well as internal alkyne coupling partners delivering a broad scope with excellent functional group tolerance. The synthetic applicability of this protocol reported herein was demonstrated in the total syntheses of two Topo-I-Inhibitors and two 8-oxyprotoberberine cores that can be further elaborated into the tetrahydroprotoberberine and the protoberberine alkaloid core. Moreover these building blocks were also transformed to six different tylophora alkaloids in expedient fashion.
An isomunchnone-based method for the synthesis of highly substituted 2(1H)-pyridones
Padwa, Albert,Sheehan, Scott M.,Straub, Christopher S.
, p. 8648 - 8659 (2007/10/03)
1-(Benzenesulfonyl-diazoacetyl)-pyrrolidin-2-one was prepared by a diazo transfer of 1-(benzenesulfonylacetyl)-pyrrolidin-2-one with p- acetamidobenzenesulfonyl azide and triethylamine. Treatment of the diazoimide with a catalytic quantity of rhodium(II) acetate resulted in the formation of an isomunchnone dipole, which underwent bimolecular trapping with various dipolarophiles in high yield. The initially formed cycloadducts were not isolable or observed, as they all readily underwent ring opening to give the 3-hydroxy-2(1H)-pyridone ring system. The 3-hydroxy-2(1H)pyridones were readily converted to the corresponding triflates, which function as suitable substrates in various types of palladium-catalyzed cross-coupling reactions. Commercial tetrakis(triphenylphoshine)palladium was found to be a particularly effective catalyst for the cross-coupling with aryl, vinyl, and acetylenic partners. An application of the method to the synthesis of the indolizidine alkaloid (±)-ipalbidine was carried out in eight steps in 17% overall yield. The angiotensin-converting enzyme inhibitor (-)-A58365A was also synthesized by a process based on the [3 + 2]-cycloaddition reaction of a phenylsulfonyl substituted isomunchnone intermediate. The starting material for this process was prepared from L-pyroglutamic acid and involved using a diazo phenylsulfonyl substituted pyrrolidine imide. Treatment of the diazoimide with Rh2(OAc)4 in the presence of methyl vinyl ketone afforded a 3-hydroxy-2-pyridone derivative, which was subsequently converted to the ACE inhibitor in six additional steps.
Synthesis of (±)-septicine
Yerxa, Benjamin R.,Yang, Kevin,Moore, Harold W.
, p. 6173 - 6180 (2007/10/02)
The total synthesis of the indolizidine alkaloid, (±)-septicine (5) (27% overall yield) in 8 steps from dimethyl squarate is presented. The key step of the synthesis involves the ring expansion of 2,3-bis-(3,4-dimethoxyphenyl)-4-(1-pyrrolo)cyclobutenone 12 to the corresponding indolizine-5,8-dione 6. The synthesis is highly convergent and thus could be used for the synthesis of a variety of analogs.
