Synthesis of novel 2-Butadienylchromone derivatives

Chromones are a group of naturally occurring compounds with a benzoannelated ypyrone ring. A large number of chromone derivatives have been isolated from natural sources and a wide range of biological properties have been attribute to them, such as antifungal, anti-allergenic, antiviral, antitubulin, anti-hypertensive, anticancer and antioxidant activities.1 11 Studies with 2-styrylchromones demonstrated that the number and position of the hydroxyl groups in the A-ring and the 3', 4'-dihydroxy substitution on B-ring play an important role in their radical scavenger activity. In addition the molecular stabilization promoted by the carbonyl carbon C-4 and Ca=C~ double bond, also seem to contribute to the scavenging effect of these compounds. 121 Taking into account these considerations we establi sh a new synthetic route for the preparation of novel hydroxylated 2-butadienylchromone derivatives 5. Our methodology involves the condensation of methoxy-2-methylchromones zl31 with 3,4-dimethoxy- cinnamaldehyde 3141 leading to (E,E)-2-( 4-arylbuta-1 ,3-dien-l-yl)-4H-chromen-4-ones 4. The final step involves the cleavage of methyl group of 4 in order to obtain the desired hydroxylated derivatives 5 (Scheme). In this communication we will present the synthetic details of all described transformations as well as the structural characterisation (by ID and 2D NMR studies) of the new synthesi sed compounds.

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