19-Norkaur-16-en-18-oic acid, 2-((6-O-(4-azidobenzoyl)-2-O-(3-methyl-1-oxobutyl)-3,4-di-O-sulfo-beta-D-glucopyranosyl)oxy)-15-hydroxy-, dipotassium salt, labeled with carbon-14, (2beta,4alpha,15alpha)-