Synthesis of 4-arylcoumarins via Cu-catalyzed hydroarylation with arylboronic acids
(Chemical Equation Presented) In the presence of 2-4 mol % of CuOAc, methyl phenylpropiolates having a MOM-protected hydroxy group at the ortho position underwent hydroarylation with various arylboronic acids in MeOH at ambient temperature, resulting in the formation of 4-arylcoumarins in high yields after the acidic workup. This method was effectively used for the synthesis of biologically active natural and artificial compounds.
Yamamoto, Yoshihiko,Kirai, Naohiro
supporting information; experimental part
p. 5513 - 5516
(2009/05/27)
An Unambiguous Synthesis of Melannein
Melannein (6-hydroxy-7-methoxy-4-(3'-hydroxy-4'-methoxyphenyl)coumarin, I) and its O,O-diethyl ether (II) have been synthesised.The steps involved in the synthesis of I and II are the respective condensation of o-methoxyhydroquinone with ethyl m-benzyloxy-p-methoxybenzoylacetate (XI) and ethyl m-ethoxy-p-methoxybenzoylacetate (III) in absolute ethyl alcohol in the presence of dry hydrogen chloride gas.The isomeric O,O-diethyl ether of melannein, viz. 6-ethoxy-7-methoxy-4(4'-ethoxy-3'-methoxyphenyl)coumarin (VI) has also been prepared by the condensation of o-methoxyhydroquinone with ethyl p-ethoxy-m-methoxybenzoylacetate (VII).The esters (III), (VII) and (XI) have been prepared by the reaction of the appropriate acetophenone derivatives with diethyl carbonate in the presence of sodium hydride.
Ahluwalia, V. K.,Kapur, Kanchan,Manchanda, Saroj
p. 186 - 188
(2007/10/02)
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