| abstract |
The present invention provides compounds of Formula I, and the tautomers thereof, and the pharmaceutically acceptable salts of the compounds and tautomers, wherein the compounds have the structure n n n n n n n n n n wherein the variables R 1 , R 2 , R 3 , R 4 and x are as defined in the specification. Corresponding pharmaceutical compositions, methods of treatment, methods of synthesis, and intermediates are also disclosed. |