- Combined directed ortho metalation/cross-coupling strategies: Synthesis of the tetracyclic A/B/C/D ring core of the antitumor agent camptothecin
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A convergent synthesis of the A/B/C/D ring fragment 5 of camptothecin using a combination of directed ortho metalation and Negishi cross-coupling is described. The key features of the synthetic sequence are an anionic ortho-Fries rearrangement (10 → 12), a Negishi cross-coupling (7 → 6), and a terminal modified von Braun reaction (16 → 5) that leads to tetracyclic derivative 5 in 7 steps and 11% overall yield.
- Nguyen, Tam,Wicki, Markus A.,Snieckus, Victor
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Read Online
- Visible-Light-Induced Radical Cascade Cyclization: Synthesis of the ABCD Ring Cores of Camptothecins
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A new strategy for constructing indolizino[1,2-b]quinolin-9(11H)-ones (ring cores of camptothecins) from readily available isocyanoarenes and N-(alkyl-2-yn-1-yl)pyridin-2(1H)-ones has been developed through a visible-light-induced radical cascade cyclization process. The reaction proceeds under mild conditions with fair to excellent yields. The easy introduction of substituents for both reactants and the broad functional group tolerance of the reaction make it a straightforward route to the cores of the marketed camptothecins and their derivatives.
- Yuan, Yao,Dong, Wuheng,Gao, Xiaoshuang,Gao, Huang,Xie, Xiaomin,Zhang, Zhaoguo
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supporting information
p. 2840 - 2846
(2018/03/09)
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- A synthetic camptothecin compound in 5-6 method of and ring structure (by machine translation)
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The present invention discloses a synthetic camptothecin compound in the 5 [...] 6 method of and ring structure, the method is that the conjugated structure of formula II occurs in the solvent alkene alkyne ester series cyclization reaction in the molecule, thus the system results in the type shown in I of the 5 [...] 6 and ring structure, the specific equation is: In the formula: R 1 and R 2 are respectively and independently selected from hydrogen, alkyl, cycloalkyl, aryl or heterocyclic group; or, R 1 and R 2 together form a saturated or unsaturated carbocyclic or heterocyclic; R 3 and R 4 are respectively and independently selected from hydrogen, alkyl, cycloalkyl, aryl or heterocyclic group; or, R 3 and R 4 together form a saturated or unsaturated carbocyclic or heterocyclic rings; selected from R C 1-C 4 alkyl; P is amino protecting group. The stated method of this invention has the advantages of simple operation, safety and environmental protection, low production cost, high yield, is suitable for large-scale production, and the like, to promote such compounds in the medical field with the extensive application of an important value. (by machine translation)
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- Tetrabutylammonium chloride-triggered 6-endo cyclization of o-alkynylisocyanobenzenes: an efficient synthesis of 2-chloro-3-substituted quinolines
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A highly efficient one-pot synthesis of 2-chloro-3-substituted quinolines has been developed by tetrabutylammonium chloride-triggered 6-endo cyclization of o-alkynylisocyanobenzenes, which are generated in situ by dehydration of the corresponding N-(2-eth
- Liu, Lanying,Wang, Yong,Wang, Honggen,Peng, Changlan,Zhao, Jiaji,Zhu, Qiang
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scheme or table
p. 6715 - 6719
(2010/01/18)
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- Traceless solid-phase synthesis of mappicine ketone library via multiple chemoselective palladium-catalyzed reactions on benzenesulfonate linker
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We report here a solid-phase synthesis of a library of mappicine ketone, a leading antiviral compound with activity against herpes viruses and human cytomegalovirus. The synthesis is based on multiple chemoselective palladium-catalyzed reactions involving
- Tsukamoto, Hirokazu,Suzuki, Risako,Kondo, Yoshinori
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body text
p. 2005 - 2010
(2009/04/10)
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- Highly efficient and mild cascade reactions triggered by bis(triphenyl)oxodiphosphonium trifluoromethanesulfonate and a concise total synthesis of camptothecin
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A mild and efficient cascade methodology is reported to construct variously substituted indolizino[1,2-b]quinolin-9(11H)-ones. Efficiently triggered by bis(triphenyl)oxodiphosphonium trifluoromethanesulfonate under mild conditions, this cascade achieved significant enhancements in chemical yields. Utilizing this highly efficient domino reaction followed by a Sharpless dihydroxylation, an eight-step total synthesis of camptothecln was accomplished from a known pyridine derivative in direct fashion with an overall yield of 47% and 95% ee.
- Zhou, Hai-Bin,Liu, Guan-Sai,Yao, Zhu-Jun
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p. 2003 - 2005
(2008/02/02)
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- Synthesis of the parent and substituted tetracyclic ABCD ring cores of camptothecins via 1-(3-aryl-2-propynyl)-1,6-dihydro-6-oxo-2- pyridinecarbonitriles
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A new synthetic pathway to the parent and substituted ABCD ring cores of the camptothecin family of alkaloids was developed. The N-alkylation of 1,6-dihydro-6-oxo-2-pyridinecarbonitrile (2) with 3-bromo-1-phenylpropyne provided 3a using Curran's protocol.
- Dai, Weixiang,Petersen, Jeffrey L.,Wang, Kung K.
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p. 4665 - 4667
(2007/10/03)
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- Concise synthesis of 11H-indolizino[1,2-b]quinolin-9-one by an aryl-aryl coupling reaction using Pd reagent
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The biaryl coupling reaction of 1-[(2-bromoquinoline-3-y1)methyl]-2(1H)-pyridinone using a catalytic amount of palladium acetate, tricyclohexylphosphine, and potassium acetate in DMF proceeded smoothly to give 11H-indolizino[1,2-b]quinolin-9-one in excellent yield.
- Harayama, Takashi,Morikami, Yosiaki,Hori, Akihiro,Nishioka, Hiromi,Abe, Hitoshi,Takeuchi, Yasuo
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p. 803 - 806
(2007/10/03)
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- Formal total synthesis of camptothecin via ring-closing metathesis strategy
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A formal total synthesis of camptothecin 1 is presented. The key steps include construction of the D-ring of camptothecin featuring an efficient ring-closing metathesis (RCM) reaction and the subsequent Michael addition of nitropropane across the double b
- Chavan, Subhash P.,Pasupathy,Venkatraman,Kale, Ramesh R.
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p. 6879 - 6882
(2007/10/03)
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- Cascade radical synthesis of heteroarenes via iminyl radicals
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A novel cascade cyclisation protocol has been developed which 'zips up' two rings to form new tetracycles. In the protocol, treatment of vinyl bromides and iodides with hexamethylditin (Me3Sn· yields intermediate vinyl radicals which undergo 5-exo cyclisation onto nitrile groups to yield intermediate iminyl radicals. The iminyl radicals can undergo 6-endo cyclisation (or 5-exo followed by neophyl rearrangement) to yield tetracyclic π-radicals which lose hydrogen (H·) in an H-abstraction step. Methyl radicals, generated from the breakdown of trimethylstannyl radicals (Me3Sn·), are proposed as a possible H-abstractor for this final oxidative step. The protocol has been used to synthesise the tetracyclic rings A-D (tetracycle indolizino[1,2-b]quinolin-9(11H)-one) of the anticancer alkaloids camptothecin, mappicine, nothapodytine B and nothapodytine A. The protocol has also been applied to the synthesis of analogues of camptothecin in which ring A has been replaced by thiophene (8,10-dihydrothieno[2′,3′:5,6]pyrido[2,3-a]indolizin-8-one) and ring D by pyrrole (10H-pyrrolizino[1,2-b]quinoline) and benzene (11H-indeno[1,2-b]quinolin-11-one).
- Bowman,Bridge,Brookes,Cloonan,Leach
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- Synthesis of heteroarenes via radical cyclisation onto nitriles
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A new protocol for the synthesis of tetracyclic nitrogen heteroarenes using cascade radical cyclisation has been developed. The key steps involve 5-exo vinyl radical cyclisation onto nitriles to yield intermediate iminyl radicals which cyclise onto an arene rings. Rings A-D of the anticancer alkaloids camptothecin, mappicine and nothapodytines A and B have been synthesised using this protocol.
- Bowman,Bridge,Cloonan,Leach
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p. 765 - 768
(2007/10/03)
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- Tandem radical reactions of isonitriles with 2-pyridonyl and other aryl radicals: Scope and limitations, and a first generation synthesis of (±)-camptothecin
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Photolysis of N-propargyl-6-halo-2-pyridones and related aromatic halides in the presence of aryl isonitriles provides tetra- and penta-cyclic products in a single step by a sequence of radical addition to the isonitrile followed by two cyclizations. The scope and limitations of the process are described along with a first generation synthesis of racemic camptothecin.
- Curran, Dennis P.,Liu, Hui,Josien, Hubert,Ko, Sung-Bo
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p. 11385 - 11404
(2007/10/03)
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