Abstract: a -Amino and a -hydroxy acids and their derivatives play an important role in organic synthesis, especially in asymmetric synthesis as chiral synthons, chiral auxiliaries, and resolving agents [1-3]. In the course of our studies of heteroaryl substituted a -amino and a -hydroxy acids and their derivatives we have prepared easily accessible 2-acylamino-3-dimethylaminopropenoates, 2-(O-substituted hydroxy)-3- dimethylaminopropenoates, and 2-ethenylamino-3-dimethylaminopropenoates, masked a -formyl-a -amino- and a - formyl-a -hydroxy acids, and their derivatives. They have turned out to be excellent reagents for the preparaton of a variety of heterocyclic systems with an amino or hydroxy acid structural element incorporated or partially incorporated into the newly formed heterocyclic ring [4]