Patent ID: 7718703

Claim:
A norvaline derivative of the formula [I]: wherein X is —CH 2 —, —O—, —S— or a single bond; Ar is a substituted or unsubstituted phenyl, a substituted or unsubstituted naphthyl, or a substituted or unsubstituted lower cycloalkyl; n is an integer of 0 to 2; R 1 and R 2 are the following (i), (ii) or (iii): (i) each is independently a hydrogen atom or a lower alkyl; (ii) R 1 and R 2 are combined together to form a lower alkylene; or (iii) R 1 is a hydrogen atom or a lower alkyl and R 2 is combined together with R 4 or R 6 to form a lower alkylene, when R is R 3 and R 4 are the following (i), (ii) or (iii): (i) each is independently a hydrogen atom or a lower alkyl; (ii) R 3 and R 4 are combined together to form a lower alkylene; or (iii) R 3 is a hydrogen atom or a lower alkyl and R 4 is combined together with R 2 or R 6 to form a lower alkylene, when R is R is or —OR 7 ; wherein R 5 and R 6 are the following (i), (ii) or (iii): (i) each is independently an unsubstituted lower alkyl or a lower alkyl substituted with hydroxyl group(s), or a hydrogen atom; (ii) R 5 and R 6 are combined together with the adjacent nitrogen atom to form an unsubstituted or substituted nitrogen-containing aliphatic 5- to 6-membered heterocyclic group; (iii) R 5 is an unsubstituted lower alkyl or a lower alkyl substituted with hydroxyl group(s), or a hydrogen atom, and R 6 is combined together with R 2 or R 4 to form a lower alkylene; R 7 is a lower alkyl; provided that when R 5 and R 6 are combined together with the adjacent nitrogen atom to form a morpholine ring, then Ar has at least one substituent other than halogen atom, methoxy or phenyl; in free form, or a pharmaceutically acceptable salt thereof.