4-hydroxy-2-quinolones 196. synthesis and bromination of 1-allyl-3-(2-hydroxyethyl)-1h,3h-quinazoline-2,4-dione

Abstract

The alkylation of 3-(2-hydroxyethyl)-1H,3H-quinazoline-2,4-dione and subsequent bromination of its 1-allyl derivative have been studied. The data obtained has been compared with the results of similar studies on a series of other, related compounds. A rule has been formulated which allows a prediction of 1-allyl-substituted 2-oxo azaheterocycles bromination route based upon the way in which their initial alkylation by allyl bromide in the system DMSO-K 2 CO 3 occurs.The bromination of cyclic compounds containing ortho located allyl and carbonyl groups can occur in two ways, viz. as a trivial addition of bromine to the allyl double bond or as a halocyclization accompanied by adding of a new bromomethyl-substituted oxazole heterocycle to the existing molecular system. Unfortunately, to this time there have been no criteria which permit a reliable prediction of such reactions direction and allow to carry out a targeted synthesis of these or related derivatives. We do not rule out that this question will be resolved in time but, for now, synthetic chemists often spend considerable time and effort in deducing the correct structure of the products formed after bromination.