Síntese de cromenonas via reações de ciclização intramolecular de alquinilarilcetonas mediada por tiol

Abstract

Due to the great relevance of chromenone derivatives in pharmacology, and consequently in organic synthesis, an efficient methodology was developed for the synthesis of 4H-chromen-4-ones derivatives through intramolecular cyclization of alkynyl aryl ketones in the presence of PhSH (1 equiv), NaOH (5 mol%) as base, using NMP (1 mL) as solvent, at reflux temperature (202 ºC) in ambient atmosphere. Through this method, it became possible to obtain a series of 4H-chromen-4-ones comprising 15 examples with yields from 23 to 95%. This methodology presents advantages for the synthesis of 4H-chromen-4-ones, since the reaction conditions lead to a high regioselectivity, by furnishing only six-membered heterocycles, after 30 minutes, besides employing base catalytic amounts in absence of transition-metal salts as well as inert reaction ambient.