The present invention provides compounds of the Formula I:
##STR1##
wherein R1 is alkyl, cycloalkyl, cycloalkylalkyl, or —CH2-alkenyl,
X1 is O, NH, N(alkyl), S or —C(O), Z is N or CH; and R2
and R3 are as defined herein, pharmaceutical compositions comprising
same, and methods for their use.
