Patent ID: 7317009

Claim:
A compound of the formula I or a pharmaceutically acceptable salt thereof, or a prodrug thereof: wherein R 1 is (1) a mono- or di(lower)alkylamino, (2) a phenyl, (3) a saturated or unsaturated 5 to 6 membered heteromonocyclic group selected from the group consisting of a pyrrolidinyl, a pyrrolyl, an oxazolyl, an isooxazolyl, a thiazolyl, a furanyl, a thienyl, and a pyridinyl, or (4) a lower alkyl optionally substituted by (i) a lower alkoxy or (ii) a saturated 5- or 6-membered heteromonocyclic group selected from the group consisting of a piperazinyl and a morpholinyl, wherein the lower alkoxy is optionally substituted by a cyclo(lower)alkyl or a pyridinyl, R 2 is R 7 or -A 2 -R 7 , wherein A 2 is —(CH2)n- or —(CH═CH)m- wherein n is an integer which may range from 2 to 6, and m is an integer of 1 to 2, and R 7 is a hydrogen, a lower alkyl sulfonyl, a carboxy, an esterified carboxy or a pyridinyl, R 3 is (1) a phenyl optionally substituted by a lower alkyl, a cyclo(lower)alkyl, a lower alkoxy, a halogen, a cyano, or a carbamoyl; or (2) a quinolinyl; or a pyridinyl substituted by a lower alkyl, a cyclo(lower)alkyl, a lower alkoxy, a carbamoyl or a halogen, and R 4 is ethyl.