To obtain a new compound capable of simply and efficiently forming a 5-acyl-4-hydroxythieno[2,3-b]pyridine skeleton, useful as an intermediate for efficiently providing a thienopyridine derivative having gonadotropic hormone releasing hormone antagonism.

This compound is shown by formula I (R11 is a 1-6C alkyl; R12 is phenyl or R11 and R12 form a 5- to 7-membered ring with two adjoining carbon atoms; R3 is a hydrocarbon; R5 is a hydrogen atom or a hydrocarbon) or its salt such as 4-hydroxy-5-isobutyryl-3-methyl-2-phenylthieno[2,3-b]pyridine. The compound is obtained by reacting a compound of formula II (R1 and R2 are each a hydrocarbon or can be bonded with two adjoining carbon atoms to form a 5- to 7-membered ring; R4 is a hydrocarbon) with a compound of formula III (R6 is a hydrogen atom, a sodium atom or the like) and subjecting a prepared new intermediate to a ring closure reaction.