Synthesis of (E)-2-(4-Arylbut-1-en-3-ynyl)-4H-chromen-4-ones
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Chromones are a well-known class of naturally occurring oxygen-containing heterocyclic
compounds; many of them playing important biological functions in nature.[IJ Although 2-
methylchromones are one of the scarcest classes of natural chromones, their synthesis and
reactivity is well studied. They can participate in several chemical transformations such as
oxidation, thiation, hydrogenation, photolysis, cycloaddition and condensation reactions,
being useful targets in the synthesis of novel heterocyclic compounds. [lJ The acidity of the
2-methyl group, due to the low electron density at C-2 caused by oxygen atom and the α, β-unsaturated ketone system, led us to explore the condensation of 2-methylchromone 2
with propargyl aldehydes 3 in order to obtain new (£)-2-( 4-arylbut-1-en-3-ynyl)-4Hchromen-
4-ones 4 (Scheme 1). The starting material, 2-methyl-chromone 2 was prepared
in a three step sequence starting from 2 '-hydroxyacetophenone 1 while the propargyl
aldehydes 3were obtained from the reaction of the appropriate iodobenzene with propargyl
alcohol and subsequent oxidation.
In this communication we will present the synthetic details of all described transformations
as well as the structural characterization (by 1 D and 2D NMR studies) of the new
synthesized compounds.
Chromones are a well-known class of naturally occurring oxygencontaining
heterocyclic compounds; many of them playing important
biological functions in nature [1]. Although 2-methylchromones are one
of the scarcest classes of natural chromones, their synthesis and
reactivity is well studied. They can participate in several chemical
transformations such as oxidation, thiation, hydrogenation, photolysis,
cycloaddition and condensation reactions, being useful targets in the
synthesis of novel heterocyclic compounds [2]. The acidity of the 2-
methyl group, due to the low electron density at C-2 caused by oxygen
atom and the α,β-unsaturated ketone system, led us to explore the
condensation of 2-methylchromones [3] with propargyl aldehydes [4].
