The present invention is directed to compounds of the general formula I and pharmaceutically acceptable salts thereof: ##STR1## wherein R=H or lower alkyl; R'=H, lower alkyl, benzyl, CH.sub.2 OH; A=(CH.sub.2).sub.1 to 5, >C(CH.sub.3).sub.2, >C (CH.sub.2).sub.3 ; and X=0 or 1. The present invention is also directed to a method of treating a person for sickle cell anemia comprising administering to the person a therapeutically effective dosage of the above compounds. In addition the invention includes the novel compound: ##STR2## which is inaccessible by synthetic procedures previously described for this general class of compounds.