| abstract |
The present invention relates to compounds of formula (I) having the structure (I), wherein the variables R 1 , R 2 , R 3 , R 4 , and x are as defined in the specification, and tautomers thereof and Provided are pharmaceutically acceptable salts of compounds and tautomeric organisms. Corresponding pharmaceutical compositions, therapeutic methods, synthetic methods, and intermediates are also disclosed. [Chemical 1] |