SIX-MEMBERED HETEROCYCLIC COMPOUNDS

PROBLEM TO BE SOLVED: To provide a new compound useful in medicinal and veterinary fields, because of having hypoglycemic action and low toxicity, and especially useful for preventing or treating diabetes and diabetic complications, such as diabetic ophthalmia, diabetic neutropathy, diabetic nephropathy, etc. SOLUTION: This compound is a six-membered heterocyclic compound of formula I A is expressed by formulae II, III or IV [(m), (n), (n1), (n2) are each 0, 1, 2 or 3; R1 is H, a halogen or the like; R2 is H, a halogen or the like; R3 and R3' are each a 1-7C alkyl; R4 is H, a 1-7C alkyl or the like; D is a covalent bond, CH2 or the like; X1, X2, X3, X4 and X5 are each N or the like, provided that at least one of the X1, X2, X3, X4 and X5 is N]} or its salt, for example, methyl (R)-3-[4-chloro-6-(2-phenoxyethoxy)pyimidin-2-yl]amino-4-tert- butoxycarbonylamino-butyrate. A compound of formula I is, for example, is obtained by reacting a compound expressed by such a formula that D-A in formula I is replaced by R16 (R16 is an eliminating group such as a halogen) with a compound expressed by the formula of H-D-A in the presence of a base in a solvent.