7-amino-1,3-dihydro-2H-imidazo[4,5-b]quinolin 2-ones and method for inhibiting phosphodiesterase and blood platelet aggregation

DETAILED DESCRIPTION OF THE INVENTION The compounds of the instant invention comprise those of Formula I ##STR15## wherein R.
sub.
1 is hydrogen, lower alkyl; R.
sub.
2 is hydrogen, lower alkyl, lower alkoxy, halogen; R.
sub.
3 is hydrogen, lower alkyl; R.
sub.
4 is hydrogen, lower alkyl, alkanoyl of 1 to 6 carbon atoms, phenylalkanoyl of 7 to 10 carbon atoms wherein phenyl is optionally substituted with halogen, lower alkyl, or lower alkoxy; R.
sub.
3 and R.
sub.
4 are joined together to form morpholinyl, piperidinyl or pyrrolidinyl optionally substituted with --CO.
sub.
2 R.
sub.
5 or ##STR16## wherein R.
sub.
5 is hydrogen or lower alkyl, and R.
sub.
6 is hydrogen, lower alkyl, cycloalkyl of 5 to 7 carbon atoms; 4-R.
sub.
7 -piperazinyl wherein R.
sub.
7 is --CO.
sub.
2 R.
sub.
8 wherein R.
sub.
8 is lower alkyl, phenyl optionally substituted with up to 2 halogen, lower alkyl or lower alkoxy; phenylalkanoyl of 7 to 10 carbon wherein phenyl is unsubstituted or independently substituted with up to 2 halogen, lower alkyl, lower alkoxy; or a pharmaceutically acceptable salt thereof.
It is understood that as used herein limitations of Formula I are defined as follows: The term "halogen" or "halo" comprehends fluorine, iodine, and most preferably bromine and chlorine.
The term "lower alkyl" refers to a branched or unbranched saturated hydrocarbon chain containing from 1 to 4 carbon atoms; specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, secondary butyl and tert.
-butyl.
The terms "alkyl of 1 to 4 carbon atoms" and "lower alkyl" are used interchangeably and specific terms may be represented by conventional symbols, i.
e.
, Me.
dbd.
CH.
sub.
3, Et.
dbd.
C.
sub.
2 H.
sub.
5, etc.
The term "lower alkoxy" comprehends ethers containing from 1 to 4 carbon atoms as defined for alkyl; such as methoxy, ethoxy, isopropoxy, tert.
-butoxy, and the like.
The term "alkanoyl of 1-6 carbon atoms" comprehends both unbranched or branched aliphatic acids such as, for example, formic acid, acetic acid, propanoic acid, butyric acid, pentanoic acid, hexanoic acid or any isomer of these acids which has up to 6 carbons atoms and is fully saturated