Patent ID: 7514433

Claim:
A compound of the formula or a pharmaceutically acceptable salt thereof, wherein: (a) R 1 is isopropyl or tert-butyl; (b) R 2 is selected from the group consisting of: (1) hydrogen; (2) lower alkyl; (3) lower halogenalkyl; (4) —SO 2 —R 5 , wherein R 5 is lower alkyl or phenyl optionally substituted by one or two substituents independently selected from the group consisting of lower alkyl, lower alkoxy, halogen, cyano, lower halogenalkyl and lower halogenalkoxy; (5) —C(O)—(CH 2 ) n -phenyl, wherein n is 0, 1 or 2 and wherein the phenyl ring is optionally substituted by one or two substituents independently selected from the group consisting of lower alkyl, lower alkoxy, halogen, cyano, lower halogenalkyl and lower halogenalkoxy; (6) —(CH 2 ) n -cycloalkyl, wherein n is 0, 1 or 2; (7) pyridyl; and (8) —(CH 2 ) n -phenyl, wherein n is 0, 1 or 2 and wherein the phenyl ring is optionally substituted by one, two or three substituents independently selected from the group consisting of lower alkyl, lower halogenalkyl, halogen, cyano, lower alkoxy and lower halogenalkoxy; (c) R 3 is hydrogen or lower alkyl; and (d) R 4 is an N-heterocyclic ring selected from the group consisting of pyrrolidine, piperidine, 1,2,3,6-tetrahydropyridine, and morpholine; wherein the nitrogen atom of the N-heterocyclic ring is substituted by a group selected from the group consisting of: (1) hydrogen; (2) lower alkyl; (3) cycloalkyl; (4) lower cyanoalkyl; (5) lower halogenalkyl; (6) lower alkoxyalkyl; (7) —SO 2 —R 6 , wherein R 6 is selected from the group consisting of: (i) lower alkyl, (ii) phenyl which is optionally substituted by one or two substituents selected from the group consisting of lower alkyl, lower alkoxy, halogen, cyano, lower halogenalkyl and lower halogenalkoxy, (iii) thienyl, and (iv) pyridyl; (8) —C(O)—R 7 , wherein R 7 is selected from the group consisting of: (i) lower alkyl, (ii) phenyl which is optionally substituted by one or two substituents selected from the group consisting of lower alkyl, lower alkoxy, halogen, cyano, lower halogenalkyl and lower halogenalkoxy, (iii) thienyl, and (iv) pyridyl; (9) —C(O)—NR 8 R 9 , wherein R 8 and R 9 independently from each other are selected from the group consisting of: (i) lower alkyl, (ii) phenyl, and (iii) lower phenylalkyl; or alternatively, R 8 and R 9 together with the nitrogen atom to which they are attached to, form a heterocyclic ring selected from the group consisting of pyrrolidine, piperidine, piperazine and morpholine, and (10) —(CH 2 ) p -phenyl, wherein p is 0, 1 or 2 and wherein the phenyl ring is optionally substituted by one or two substituents selected from the group consisting of lower alkyl, lower alkoxy, halogen, cyano, lower halogenalkyl and lower halogenalkoxy.