Pyrimidines. Part II. The photo-Fries rearrangement of 2-dialkylamino-4-pyrimidinyl esters of alkyl and arylsulphonic acids

Abstract

The photo-Fries reaction of 2-dialkylamino-4-pyrimidinyl esters of alkyl and arylsulphonic acids, in which the pyrimidine 5-position is unsubstituted, affords the corresponding 5-alkylsulphonyl and 5-arylsulphonyl-2-dialkylamino-4-hydroxypyrimidines respectively, in yields of up to 60%, together with smaller amounts of the parent 2-dialkylamino-4-hydroxypyrimidine. Certain 2-amino- and 2-acetylamino-4-pyrimidinyl esters of aryl sulphonic acids fail to undergo the photo-Fries reaction, but instead photo-induced solvolysis occurs with the formation of the aryl sulphonic acid salt of the related 2-amino-4-hydroxypyrimidine.