The present invention provides compounds of formula Ia and Ib
or a pharmaceutically acceptable salt, prodrug, or ester thereof, useful in the inhibition of neuraminidase enzymes from disease-causing microorganisms, especially influenza neuraminidase, pharmaceutical formulations containing same, processes and intermediates for preparing said compounds, as well as methods of using said compounds, including preventing and treating diseases caused by microorganisms having said neuraminidase enzyme.