Toluene-4-sulfonic acid (R)-2-(tert-butyl-dimethyl-silanyloxy)-1-[(3aR,5S,6S,6aR)-2,2-dimethyl-6-((R)-4-oxo-azetidin-2-yloxy)-tetrahydro-furo[2,3-d][1,3]dioxol-5-yl]-ethyl ester