182275-70-3Relevant articles and documents
Visible-Light-Induced Radical Cascade Cyclization: Synthesis of the ABCD Ring Cores of Camptothecins
Yuan, Yao,Dong, Wuheng,Gao, Xiaoshuang,Gao, Huang,Xie, Xiaomin,Zhang, Zhaoguo
supporting information, p. 2840 - 2846 (2018/03/09)
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.
Highly selective metalations of pyridines and related heterocycles using new frustrated lewis pairs or tmp-zinc and tmp-magnesium bases with bf 3·oet2
Jaric, Milica,Haag, Benjamin A.,Unsinn, Andreas,Karaghiosoff, Konstantin,Knochel, Paul
supporting information; experimental part, p. 5451 - 5455 (2010/09/16)
(Figure Presented) Efficient and selective: Frustrated Lewis pairs based on BF3·OEt2 and LiCl-com-plexed tmpMg or tmpZn amides (tmp = 2,2,6,6-tetramethylpiperidyl) allow the efficient and regioselective metalation of various functionalized N heterocycles (see scheme for examples). Moreover, such metalations carried out in the presence or absence of BF 3·OEt2 enable a complete switch of regioselectivity, thus allowing complementary fuctionalization.
A general synthetic approach to the (20s)-camptothecin family of antitumor agents by a regiocontrolled cascade radical cyclization of aryl isonitriles
Josien, Hubert,Ko, Sung-Bo,Bom, David,Curran, Dennis P.
, p. 67 - 83 (2007/10/03)
A general and efficient synthesis of (20S)-camptothecin (1a) is reported. A key common intermediate containing the pyridone and lactone (DE) rings of camptothecin and most derivatives was constructed from 2-trimethylsilyl-6-methoxypyridine by a series of metalation reactions and a Heck cyclization to provide an achiral bicyclic enol ether. Sharpless asymmetric dihydroxylation followed by lactol oxidation and iododesilylation produced the key intermediate in 94% enantiomeric excess. Alkylation with prop-argyl bromide and a cascade radical reaction with phenyl isonitrile then produced 1a. About 20 other penta-and hexacyclic analogues of camptothecin with differing single or multiple substituents at C7, C9, C10, C11, and/or C12 were made by changing the propargylating agent and the isonitrile. Included among these are several drug candidates and the approved drugs topotecan and irinotecan. The synthesis of the prodrug irinotecan is a direct one that does not pass through the active metabolite. The use of ortho-trimethylsilyl-substituted isonitriles allows the regioselective synthesis of camptothecin analogues in cases where isomeric mixtures are formed from the parent isonitriles. The synthesis of the derivatives relies on the broad scope and functional group tolerance of the key cascade radical reaction.
