Derivatives of condensed compounds containing the thieno[2,3-b]pyridine system as a fragment display valuable biological properties [1,2]. In order to obtain and study the biological activity of new compounds in this series, we developed a method for their synthesis starting from 3-amino-7,7-dimethyl7,8-dihydro-5H-pyrano[4,3-b]thieno[3,2-e]pyridine-2-carboxylic acid (1).Acid 1 was obtained by the hydrolysis of its ethyl ester [3] using aqueous sodium hydroxide. This acid was previously synthesized from 3-cyano-7,7-dimethyl-2-sulfanyl-7,8-dihydro-5H-pyrano[4,3-b]pyridine and bromoacetic acid [4]. Heating amino acid 1 with acetic anhydride (2a) or butyric anhydride (2b) at reflux leads to 2-methyl-(3a) or 2-propyl-8,8-dimethyl-7,10-dihydro-4H,8H-pyrano[3",4":5',6']pyrido[3',2':4,5]thieno-[3,2-d][1,3]oxazin-4-one (3b). A study of the reaction of compounds 3a and 3b with primary amines 4a-h showed that various products are formed depending on the structure of these amines. Thus, amines 4a-e gave derivatives of 7,10-dihydro- 8H-pyrano[3",4":5',6']pyrido[3',2':4,5]thieno[3,2-d]pyrimidine 5a-j in 63-76% yield. Under the same conditions, sterically hindered amines 4f-h gave 7,8-dihydro-5H-pyrano[4,3-b]-thieno[3,2-e]pyridine derivatives 6a-f in 63-67% yield. Thienopyridine derivatives 6a-f do not cyclize even upon prolonged heating.