4281-39-4Relevant articles and documents
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.
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.
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).
