4281-39-4Relevant academic research and scientific papers
Coumarins by Direct Annulation: β-Borylacrylates as Ambiphilic C3-Synthons
Wienhold, Max,Molloy, John J.,Daniliuc, Constantin G.,Gilmour, Ryan
supporting information, p. 685 - 689 (2020/11/30)
Modular β-borylacrylates have been validated as programmable, ambiphilic C3-synthons in the cascade annulation of 2-halo-phenol derivatives to generate structurally and electronically diverse coumarins. Key to this [3+3] disconnection is the BPin unit which serves a dual purpose as both a traceless linker for C(sp2)–C(sp2) coupling, and as a chromophore extension to enable inversion of the alkene geometry via selective energy transfer catalysis. Mild isomerisation is a pre-condition to access 3-substituted coumarins and provides a handle for divergence. The method is showcased in the synthesis of representative natural products that contain this venerable chemotype. Facile entry into π-expanded estrone derivatives modified at the A-ring is disclosed to demonstrate the potential of the method in bioassay development or in drug repurposing.
Phosphine-catalyzed β′-umpolung addition of nucleophiles to activated α-alkyl allenes
Martin, Tioga J.,Vakhshori, Venus G.,Tran, Yang S.,Kwon, Ohyun
, p. 2586 - 2589 (2011/06/25)
Highly functionalized alkenes can be prepared through phosphine-catalyzed β′-umpolung additions of nucleophiles (carbon-, oxygen-, nitrogen-, and sulfur-centered) to activated α-disubstituted allenes, providing many potentially useful synthetic intermediates in good to excellent yields, often with high levels of stereoselectivity for the product olefin geometry. Various substitution patterns around the allene are compatible with the process, showcasing the synthetic utility of allenes under the conditions of nucleophilic phosphine catalysis.
Synthesis of coumarins, 4-hydroxycoumarins, and 4-hydroxyquinolinones by tellurium-triggered cyclizations
Dittmer, Donald C.,Li, Qun,Avilov, Dimitry V.
, p. 4682 - 4686 (2007/10/03)
Coumarins, 4-hydroxycoumarins, and 4-hydroxyquinolin-2(1H)-ones can be conveniently prepared by treatment of α-halocarboxylic acid esters of salicylaldehyde, o-hydroxyacetophenone, methyl salicylate, and methyl N-methyl- or N-phenylanthranilates with sodium or lithium telluride. Phenylketene formation competes with cyclization of the α-chlorophenylacetate ester of methyl salicylate as demonstrated by a trapping experiment with benzylamine. Elemental tellurium may be recovered and reused.
Synthesis of Coumarins and Quinolones by Intramolecular Aldol Condensation Reactions of Titanium Enediolates
Fuerstner, Alois,Jumbam, Denis N.,Shi, Nongyuan
, p. 326 - 332 (2007/10/02)
Low-valent titanium prepared by the reduction of TiCl3 with zinc dust oxidatively adds to α-ketoamides or α-ketoesters with the formation of the corresponding titanium enediolates.These 1,2-difunctional nucleophiles, which have hardly been used in organic
A General Synthesis of 3,4-Disubstituted Coumarins
Patil, Vinayak O.,Kelkar, Shriniwas L.,Wadia, Murzban S.
, p. 674 - 675 (2007/10/02)
The complex of POCl3 and the substituted N,N-diethylacetamide is condensed with substituted o-hydroxy-acetophenones and -benzophenones to afford 3,4-disubstituted coumarins (1a-k).
Facile Synthesis of 3-Methyl-5,6-dihydro-2H-pyran-2-ones and 3-Methylcoumarines under Mild Conditions
Falsone, Gioacchino,Spur, Bernd,Wingen, Peter H.
, p. 763 - 766 (2007/10/02)
The synthesis of the 3-methyl-5,6-dihydro-2H-pyran-2-one, 3, 5 and the 3-methylcoumarines 7a-e from the β-hydroxyoxo compounds 1,4,6a-c and the phosphonopropionic acid 2 under Wittig-Horner conditions is described.
